NM8N MCCB P- 001

1. General
The NM8N series moulded case circuit breaker is suitable for AC circuits with frequencies of 50/60Hz,
rated voltages up to AC 690V, and DC systems with rated voltages up to DC 1000V. It has a rated
current range from 16A to 1600A. This circuit breaker provides protection against overload, short circuit,
and undervoltage conditions. Additionally, it offers the same protection for infrequent motor starts.

The products offer power distribution protection, motor protection, residual current protection, and
isolation.

The circuit breaker can be installed vertically or horizontally and supports both top and bottom line entry
configurations.

Compliance with Standards：

IEC 60947-1 general rules for low-voltage switchgear and control equipment;
IEC 60947-2 low-voltage switchgear and control equipment circuit breakers;
IEC 60947-3 low-voltage switchgear and control equipment switches,
disconnectors and fuse combination appliances;
IEC 60947-4-1 Electromechanical contactors and motor starters (including motor protectors) for low
voltage switchgear and control equipment.

2. Operating conditions
2.1 Temperature:
Operating and storage temperature is -40°C~+70°C; the average value within 24 hours does not
exceed +35°C; when the ambient temperature is -40°C~+70°C, users need to consider derating or
temperature compensation whose details can be referred to in Sections 10.3 and 10.4.
2.2 Altitude: ≤ 2000m;

2.3 Pollution grade: Grade 3;

2.4 IP grade: IP40

2.5Environmental conditions:
At the mounting site, relative humidity should not exceed 50% at a maximum temperature of +40°C.
Higher humidity is permissible at lower temperatures, such as 90% RH at +20°C. Special measures
should be taken to prevent dew formation.
P- 002 MCCB NM8N

3. Type designation
3.1 NM8N Moulded Case Circuit Breaker and Switch Disconnector

Special application

Poles:
1P: 1-pole
2P: 2-pole
3P: 3-pole
4B: 4-pole, there is no over-current protection at
pole N and N-pole operates with other three poles
4C: 4-pole, there is over-current protection at pole N
and N-pole operates with other three poles

Rated Current corresponding to Frame Size

125 : 16-20-25-32-40-50-63-80-100-125
250 : 32-63-100-125-160-180-200-225-250
400 : 250-315-350-400
630 : 400-500-630
800 : 500-630-700-800
1600 : 800-1000-1250-1600

Release type code

TM: Thermal-magnetic type
EN: Basic electronic type for power distribution
EM: Standard electronic type for power distribution
M: Magnetic type for motor protection
ENM: Basic electronic type for motor protection
EMM: Standard electronic type for motor protection
Blank：Switch disconnector type

Breaking capacity code: B, C, S, Q, H, R

(Switch disconnector type has no code)

Frame Size :
125：125A；250：250A；400：400A
630：630A；800：800A；1600：1600A

DC: DC MCCB
Blank: AC MCCB
SD: Switch disconnector

Design code

Design sequence number

MCCB

Company code
 NM8N MCCB P- 003

3.2 NM8NL Residual Current Breaker

Rated residual current code:

RCD1 X:0.03-0.05-0.1-0.2-0.3-0.5-1-2A

Rated residual current type:

Default: AC type, A: A type

Pole code:
3P: 3-pole
4P: 4-pole
Frame size rated current:
125：125A；250：250A；400：400A；630：630A
Residual current code

Design code

Design sequence number

MCCB

Company code
 P- 004 MCCB NM8N

4. Technical data
NM8N Moulded Case Circuit Breaker 125 250
Magnetic type 16-20-25-32-40-50-63-80-100-125 125-160-180-200-225-250
Rated operating
Thermal-magnetic type 16-20-25-32-40-50-63-80-100-125 125-160-180-200-225-250
current In (A),40℃
Electronic type — 32-63-100-160-250
Electric characteristics
Rated insulation voltage Ui (V) 1000 1000
Rated impulse withstand voltage Uimp (kV) 8 8

Rated operational voltage Ue(V),AC 50/60Hz 380/400/415,440,500,660/690 380/400/415,440,500,660/690

Breaking capacity code C S Q H R C S Q H R

1P ■ ■ — — — ■ ■ — — —
2P ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
Number of poles
3P ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
4P ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
AC220/230/240V1) 36 50 — — — 36 50 — — —
AC380/400/415V 36 50 70 100 150 36 50 70 100 150
Rated ultimate
short-circuit breaking AC440V 36 50 70 100 100 36 50 70 100 100
capacity Icu (kA)
AC500V 25 40 40 50 50 25 40 40 50 50
AC660/690V 6 8 8 10 10 6 8 8 10 10
AC220/230/240V1) 36 50 — — — 36 50 — — —
AC380/400/415V 36 50 70 100 150 36 50 70 100 150
Rated ser vice shor t- circuit
AC440V 36 50 70 100 100 36 50 70 100 100
breaking capacity (kA)
AC500V 25 40 40 50 50 25 40 40 50 50
AC660/690V 6 8 8 10 10 6 8 8 10 10
Rated short-time withstand current Icw (kA,1s) — 1(32A,63A);2(100A,160A);3(250A)
Standard IEC/EN 60947-2

Utilization category A A

Ambient temperature -40℃ ~+70℃ 2)

Suitable for Isolation ■ ■
Arcing distance 0 0
Mechanical life
Maintenance 25000 25000
(CO recycle)
Electrical life AC415V,In 10000 10000
(CO recycle) AC690V,In 2000 1500
Release units
TM ■ ■
Distribution protection EN — ■
EM — ■
M ■ ■
Motor protection ENM — ■
EMM — ■
Mounting and connection
Front connection ■ ■
Fixed
Rear connection ■ ■
Front connection ■ ■
Plug-in3)
Rear connection ■ ■

3)
Front connection — —
Withdrawable
Rear connection — —
DIN rail Front connection ■ ■
Dimension
Width (1P/2P/3P/4P) 35/62/90/120 10/70/105/140
Dimension (mm)
Height 140 157
W×H×D
Depth 78.5 88.7
Weight
1P 0.5 0.75
2P 0.83 1.3
Weight(kg)/Fixed
3P 1.19 1.85(EM/M) ; 2.0(EN/EM)
4P 1.55 2.5(TM/M) ; 2.65(EN/EM)
1)
Note : For 1 pole product only;
2)
The operating temperature of basic (dial code) electronic type is -35℃ ~+70℃ ,and the operating temperature
of standard (liquid crystal) electronic type is -25℃ ~+70℃ ;
3)
For 3/4 pole product only;
4)
The data in "()" is for motor type.
 NM8N MCCB P- 005

400 630 800 1600

250-315-350-400 400-500 500-630-700-800 —
250-315-350-400 400-500 500-630-700-800 800-1000-1250-1600
250-400 400-630 630-800 800-1000-1250-1600

1000 1000 1000 1000

12 12 12 8
380/400/415,440,
380/400/415,440,500,600/690 380/400/415,440,500,660/690 380/400/415,440,500,660/690
500,660/690
C S Q H R C S Q H R C S Q H R S Q H
— — — — — — — — — — — — — — — — — —
— — — — — — — — — — — — — — — — — —
■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
— — — — — — — — — — — — — — — — — —
36 50 70 100 150 36 50 70 100 150 36 50 70 100 150 50 70 100
36 50 70 100 100 36 50 70 100 100 36 50 70 100 100 50 65 65
25 40 40 50 50 25 40 40 50 50 25 40 40 50 100 40 50 50
10 12 12 15 15 10 12 12 15 15 12 15 15 20 30 30 30 30
— — — — — — — — — — — — — — — — — —
36 50 70 100 150 36 50 70 100 150 36 50 70 100 150 50 70 70
36 50 70 100 100 36 50 70 100 100 36 50 70 100 100 40 50 50
25 40 40 50 50 25 40 40 50 50 25 40 40 50 100 30 40 40
10 12 12 15 15 10 12 12 15 15 12 15 15 15 15 30 30 30
5 5(400A);8(630A) 10 20
IEC/EN 60947-2
A(Thermal-magnetic)/
A(Thermal-magnetic)/B(Electronic) A(Thermal-magnetic)/B(Electronic) A(Thermal-magnetic)/B(Electronic)
B(Electronic）
2)
-40℃ ~+70℃
■ ■ ■ ■
0 0 0 0

20000 20000 20000 10000

8000 8000 8000 3000

1500 1500 1000 1000

■ ■ ■ ■
■ ■ ■ ■
■ ■ ■ ■
■ ■ ■ ■
■ ■ ■ —
■ ■ ■ —

■ ■ — ■
■ ■ ■ —
■ ■ — —
■ ■ — —
■ ■ ■ —
■ ■ ■ —
— — — —

140/185 140/185 195/260 210/280

255 255 300 286
113 113 133 167（195）4)

— — — —
— — — —
5.2(TM/M) ; 6.7(EN/EM) 5.5(TM/M) ; 7.0(EN/EM) 10.5(TM/M) ; 10.5(EN/EM) 13.5(16)4)
5.8(TM/M) ; 7.8(EN/EM) 5.8(TM/M) ; 7.8(EN/EM) 13.5(TM/M) ; 13.5(EN/EM) 17.5(20)4)
 P- 006 MCCB NM8N

NM8N DC Moulded Case Circuit Breaker 125 250

Rated operating current In (A),40℃ 16-20-25-32-40-50-63-80-100-125 125-160-180-200-225-250

Electric characteristics

Rated insulation voltage Ui (V) 1000 1000

Rated impulse withstand voltage Uimp (kV) 8 8

Rated operational voltage Ue (V),DC 250 , 500 , 750 , 1000 250 , 500 , 750 , 1000

Breaking capacity code B C S Q H B C S Q H

1P ■ ■ ■ — — ■ ■ ■ — —

2P ■ ■ ■ ■ ■ ■ ■ ■ ■ ■
Number of poles
3P ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

4P ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

DC250V 1P 25 36 50 — — 25 36 50 — —
Rated ultimate DC500V 2P in series 25 36 50 70 100 25 36 50 70 100
short-circuit breaking
capacity Icu(kA) DC750V 3P in series 25 36 50 70 100 25 36 50 70 100

DC1000V 4P in series 25 36 50 70 100 25 36 50 70 100

DC250V 1P 25 36 50 — — 25 36 50 — —
Rated service DC500V 2P in series 25 36 50 70 100 25 36 50 70 100
short-circuit breaking
capacity (kA) DC750V 3P in series 25 36 50 70 100 25 36 50 70 100

DC1000V 4P in series 25 36 50 70 100 25 36 50 70 100

Standard IEC/EN 60947-2

Utilization category A A

Ambient temperature -40℃ ~+70℃

Suitable for Isolation ■ ■

Arcing distance 0 0
Mechanical life
Maintenance free 15000 15000
(CO recycle)
Electrical life
DC1000V,In 2000 1500
(CO recycle)
Release units

Distribution protection TM ■ ■

Mounting and connection

Front connection ■ ■
Fixed
Rear connection ■ ■

Front connection ■ ■
Plug-in1)
Rear connection ■ ■

Front connection — —
Withdrawable1)
Rear connection — —

DIN rail Front connection ■ ■

Dimension

Width(1P/2P/3P/4P) 35/62/90/120 40/70/105/140

Dimension(mm)
Height 140 157
W×H×D
Depth 78.5 88.7

Weight

1P 0.5 0.75

2P 0.83 1.3
Weight(kg)/Fixed
3P 1.19 1.85

4P 1.55 2.5
1)
Note : For 3/4 pole product only.
 NM8N MCCB P- 007

400 630 800 1600

8 0 0 -10 0 0 -
250-315-350-400 400-500 500-630-700-800 1250-
1600

1000 1000 1250 1000

12 12 12 8

750 ， 1000 750 , 1000 750 , 1000 750 , 1000

B C S Q H B C S Q H B C S Q H B C

— — — — — — — — — — — — — — — — —

— — — — — — — — — — — — — — — — —
■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

— — — — — — — — — — — — — — — — —

— — — — — — — — — — — — — — — — —

25 36 50 70 100 25 36 50 70 100 25 36 50 70 100 25 36

25 36 50 70 100 25 36 50 70 100 25 36 50 70 100 25 36

— — — — — — — — — — — — — — — — —

— — — — — — — — — — — — — — — — —

25 36 50 70 100 25 36 50 70 100 25 36 50 70 100 25 36

25 36 50 70 100 25 36 50 70 100 25 36 50 70 100 25 36

IEC/EN 60947-2

A A A A

-40℃ ~+70℃
■ ■ ■ ■

0 0 0 0

15000 15000 10000 6000

1500 1500 1000 1000

■ ■ ■ ■

■ ■ — ■

■ ■ ■ —
■ ■ — —
■ ■ — —
■ ■ ■ —
■ ■ ■ —

— — — —

140/185 140/185 195/260 210/280

255 255 300 286

113 113 133 167

— — — —

— — — —

5.2 5.5 10.3 13.5

6.7 7 13.5 17.5

 P- 008 MCCB NM8N

NM8NL Residual Current protection module 125 250 400 630

Rated operating current In (A), 40℃ 125 250 400 630

Number of poles 3P、4P 3P、4P 3P、4P 3P、4P

Electric characteristics

Rated insulation voltage Ui (V) 1000 1000 1000 1000

Rated insulation voltage Uimp (kV) 8 8 12 12

Rated operational voltage Ue(V),AC 50/60Hz 380/400/415、440 380/400/415、440 380/400/415、440 380/400/415、440

16-20-25-32-40-50-63- 125-160-180-200-225-
TM 250-315-350-400A 400-500A
80-100-125 250
EN — 32-63-100-160-250 250-400 400-630

Rated current (A) EM — 32-63-100-160-250 250-400 400-630

of circuit breaker 16-20-25-32-40-50-63- 125-160-180-200-225-
M 250-315-350-400A 400-500A
80-100-125 250
ENM — 32-63-100-160-250 250-400 400-630

EMM — 32-63-100-160-250 250-400 400-630

Rated residual operating RCD1 X ( Eight-step
0.03-0.05-0.1-0.2-0.3-0.5-1-2
current I △ n(A) adjusable )
Rated residual non-operating current I △ no(A) 0.5I △ n 0.5I △ n 0.5I △ n 0.5I △ n
1)
Limit non-actuating time △ t (ms) 0-60-200-500-1000-2000
Maximum breaking Total breaking time
100-300-500-1000-2000-3000
time (ms) (adjustable)
Rated residual making and breaking capacity
0.25Icu 0.25Icu 0.25Icu 0.25Icu
I △ m(kA)
Leakage alarm non-tripping function □ □ □ □

Standard IEC/EN 60947-2

Residual current type A/AC A/AC A/AC A/AC

Suitable for Isolation ■ ■ ■ ■

Ambient temperature -25℃ ~+70℃

Arcing distance 0 0 0 0

Dimension

Width ( 3P/4P ) 90/120 105/140 140/185 140/185

Dimension with circuit
breaker (mm) Height 205 232 355 355
W×H×D
Depth 78.5 88 113 113

Weight

Weight of residual current 3P 0.43 0.84 1.98 1.98

protection module (kg) 4P 0.51 1.08 2.69 2.68

Note : 1) When the residual operating current is set to 0.03A, the limit non-actuating time must be set to 0.
 NM8N MCCB P- 009

NM8NSD Switch Disconnector 125 250 400 800 1600

NM8NSD Switch Disconnector
125 250 400 800 1600
Ith(A),40℃
Number of poles 2P 3P 4P 2P 3P 4P 3P 4P 3P 4P 3P 4P
800-1000-1250-
Rated operational current Ie(A) 125 250 400 800
1600

Rated operational AC (50/60Hz) 690 690 690 690 415/690

voltage Ue(V) DC 500 750 1000 500 750 1000 750 1000 750 1000 750 1500
AC : 1000
Rated insulation voltage Ui(V) 1000 1000 1000 1250
DC ： 1500
Rated impulse withstand
8 8 12 12 12
voltage Uimp(kV)
Rated short-circuit making capacity
3.2（AC)/2(DC) 5(AC)/3.2(DC) 8(AC)/5(DC) 14 40(AC)/19.2(DC)
Icm(kA)
Rated short-time 1s 2 3.2 5 8/10 20(AC)/19.2(DC)
withstand current
Icw(kA) 3s 2 3.2 5 8/10 20

Standard IEC/EN 60947-3, GB/T 14048.3

AC-22A/AC-23A AC-22A/AC-23A AC-22A/AC-23A AC-22A/AC-23A AC-22A/AC-23A
Utilization category
DC-22A/DC-23A DC-22A/DC-23A DC-22A/DC-23A DC-22A/DC-23A DC-22A/DC-23A
Suitable for Isolation ■ ■ ■ ■ ■

Ambient temperature -40℃ ~+70℃

Arcing distance 0 0 0 0 0
Mechanical life
Maintenance free 15000 15000 15000 10000 6000
(CO recycle)
AC415V,In 8000 6000 4000 2000 1000
Electrical life
AC690V,In 2000 1500 1500 1000 1000
(CO recycle)
DC1000V,In 2000 1500 1500 1000 1000

Mounting and connection

Front connection ■ ■ ■ — ■
Fixed
Rear connection ■ ■ ■ ■ ■

Front connection ■ ■ ■ — —
Plug-in1)
Rear connection ■ ■ ■ — —

Front connection — — ■ ■ —
Withdrawable1)
Rear connection — — ■ ■ —

DIN rail Front connection ■ ■ — — —

Dimension

Width(2P/3P/4P) 62/90/120 70/105/140 140/185 195/260 210/280

Dimension(mm)
Height 140 157 255 300 286
W×H×D
Depth 78.5 88.7 113 133 167(195)2)

Weight

2P 0.81 1.1 — — —

Weight(kg)/Fixed 3P 1.05 1.75 5 9.5 13(15.5)2)

4P 1.5 2.4 5.5 12.5 17(19.5)2)

Note : 1) For 3/4 pole product only;

2)
The data in "()" is for motor type.
P- 010 MCCB NM8N

5. Release
5.1 Protection for power distribution
5.1.1 Thermal-magnetic type release TM
Thermal-magnetic release of NM8N-125, 250, 400, 630, 800 and 1600 breakers can be set to meet
protection requirements

In In

Thermal-magnetic
125 250 400 630 800 1600
release TM
2P/3P
Number of poles 1P 1P 2P/3P/4P 3P/4P 3P/4P 3P/4P 3P/4P
4P
16/20/25 125/160 180
125 250/315 500/630 800/1000
Rated current 32/40/50 180/200 200/225 400/500
160 350/400 700/800 1250/1600
63/80/100/125 225/250 250
Over-load protection
1.0 0.7- 1.0
Setting current 0.7-0.8-
Non- 0.8- Non- 0.7-0.8-0.9-1.0
( A ) Ir=Inx 0.9-1.0
adjustable 0.9-1.0 adjustable
Short-circuit instantaneous protection
7-8-
Setting current
10 10 9-10- 5-6-7-8-9-10 6-7-8-9-10
( A ) Ii=Inx
11-12
Accuracy ±20%
N-pole protection
Setting current
/ 10 / The same with the other three-phase poles.
( A ) IiN=Inx
Accuracy ±20%

5.1.2 Basic electronic type release for power distribution EN

The EN Basic electronic trip unit provides three-stage protection: overload long-time protection, short
circuit short-time protection, and short circuit instantaneous protection.

Electronic type EN 250 400 630 800 1600

O v e r l o a d l o n g - Setting current Ir=Inx 0.4-0.5-0.6-0.7-0.8-0.9-0.95-1.0
time protection and
time delay setting 6Ir Tripping time Tr(s) 3-6-12-18, Accuracy ±10%

Short circuit short- Setting current I sd=Ir x 1.5-2-3-4-6-8-10, OFF, Accuracy ±15%
time protection and 0.1-0.2-0.3-0.4, Accuracy ±20% or ±40ms(higher value will
time delay setting Tripping time Tsd(s) be selected)
Short circuit Setting current Ii=Inx 2-3-4-6-8-10-12, OFF, Accuracy ±15%
instantaneous
protection Max. tripping time (ms) 60
IrN=(0.5,1)xIn, OFF; I sdN=(1.5-2-3-4-6-8-10)IrN
Neutral line Setting current
IiN=(2-3-4-6-8-10-12)IrN
protection
Tripping time (s) The same with the other three-phase poles.

● Overload long-time protection and long-time delay setting

—The long-time current setting (Ir) can be adjusted according to user requirements. The long-time
delay (Tr) corresponds to 6 times the current setting Ir.
● Short circuit short-time protection and short-time delay setting
—The current value (Isd) and the tripping time-delay (Tsd) can both be adjusted to meet user
requirements.
● Short circuit instantaneous protection characteristics setting
—The current value Ii can be adjusted according to the user's needs.
● Neutral line protection feature setting
The four-pole circuit breaker N-pole protection current value can be adjusted according to user
needs. The N pole tripping time is the same with the other three-phase poles.

5.1.3 Standard electronic type release for power distribution EM

The EM release offers four-stage protection: overload long-time protection, short circuit short-time
protection, short circuit instantaneous protection, and earth fault protection. It also provides real-time
current display and adjustable protection parameters.
 NM8N MCCB P- 011

The EM release information display, fault information display, and parameter setting functions.

Electronic type EM 250 400 630 800 1600

Overload long- Setting current Ir=Inx 0.4~1.0, Stepping1A
time protec tion
and time-delay 6Ir Tripping time Tr(s) 3~18, 1s, Accuracy ±10%
setting
Short circuit short- Setting current I sd=Ir x 1.5~10, Stepping1A, OFF, Accuracy ±15%
time protec tion
and time delay 0.1-0.2-0.3-0.4, Accuracy ±20% or ±40ms(higher value will
Tripping time Tsd(s)
setting be selected)
Short circuit Setting current Ii=Inx 1.5~12, Stepping1A, OFF, Accuracy ±15%
instantaneous
protection Max. tripping time (ms) 60
Setting current I g=Inx 0.4-0.5-0.6-0.7-0.8-0.9-1.0, OFF, Accuracy ±15%
Earth fault
protection Tripping time (s) 0.1-0.2-0.3-0.4, Accuracy ±15%

● Overload protection and tripping time setting

— Current setting value Ir, the user can adjust the range according to the ↑ and ↓ buttons on
the panel, the range is (0.4~1.0) In, and the tripping time Tr is at the status of 6Ir, which can be
adjusted according to user needs.
● Short circuit short-time protection and delay setting
—The current setting value (Isd) can be adjusted according to user needs, with an "OFF" option to
disable the function. The short-time delay (Tsd) can also be adjusted to user specifications.
● Short circuit instantaneous protection setting
—The current setting value (Ii) can be adjusted according to the user's needs, and the function can
be disabled using the "OFF" option.
● Neutral line protection feature setting
—For the four-pole circuit breaker, the neutral line protection (current setting value IrN) can be
adjusted within the range of 0.5In, 1In, or OFF, based on user preferences. The "OFF" position
indicates that the N pole protection is disabled.
● Earth fault protection
The earth fault setting (Ig) can be adjusted according to user needs. Selecting "OFF" disables the
function entirely.

5.2 Protection for motor

5.2.1 Motor starting characteristics
Currently, most motors are three-phase asynchronous induction motors, with many employing
direct start, where electric energy directly initiates motor operation without restrictions — also known
as full-voltage start. During starting, asynchronous motors experience a high initial current, typically
4 to 7 times their rated current. This surge occurs because the motor possesses inertia, preventing
immediate rotor speed adjustment to rated levels upon start. Consequently, the relative rotational
speed between the stator's rotating magnetic field (slightly higher than rated speed) and the rotor is
significant. This rapid speed differential causes the rotor winding to cut through the stator magnetic
field swiftly, generating a substantial current. Simultaneously, the strong current induced in the
rotor's magnetic field further induces current in the stator winding, leading to a rapid increase in
overall current.
Startup parameter
Rated current (In ): current value of the motor under rated operation
Starting current (Id): The current when the motor starts, its magnitude varies with different
conditions, the average value is 7.2×In
Start peak current (Id): Transient current during the first two half-waves after the motor is powered
on, typically 14 × In
Start-up time (td): generally 0.5~20s, which refers to the time when the motor has starting current
Direct startup impact on the protection device
In circuit breakers equipped with magnetic protection, an incorrectly setting for the
magnetic trip unit can cause the breaker to mistake the motor's starting current for a
short-circuit, leading to nuisance trips. Similarly, independent thermal overload relays
can trip due to heat generated by the motor's large starting current. Contactors used
for electric or regenerative braking of the motor need to handle interruptions during the
starting phase and typically require derating to prevent protection device malfunctions.

To ensure proper operation:

a.The inverse time characteristic curve of the in dependent thermal overload relay should be entirely
above the motor's starting currenr.
b. The short-circuit trip setting of the circuit breaker with magnetic protection must exceed the peak
starting current of the motor.
5.2.2 Protection solution
The NM8N Series offers start-up, control and protection solutions for two three-phase
asynchronous motors:
P- 012 MCCB NM8N

Three-component solution
Magnetic type circuit breaker + Contactor + Thermal overload relay
(Note: Magnetic type is chosen to be consistent with the earlier pages)
In this system, the magnetic type circuit breaker is used for short circuit protection, the contactor is
used for motor operation, and the thermal overload relay provides overload, phase loss, and phase
unbalance protection.
1）Magnetic type release M
The electromagnetic protection circuit breaker has a current range of 125~800A, an adjustable
range of 9~14In and an accuracy of 20%. It is especially suitable for use in the classic
threecomponent protection solution.

Ii

Magnetic M 125 250 400 630 800

Pole 3P/4P 3P/4P 3P/4P 3P/4P 3P/4P
Short circuit instantaneous protection
Setting current ( A ) Ii=Inx 12 9-10-11-12-13-14
Accuracy ±20%
N pole protection
Setting current ( A ) IiN=Inx 12 The same with the other three-phase poles.Ii
Accuracy ±20%
Two-component solution
Integrated protection electronic circuit breaker + contactor
In the two-component solution, there is no need for a thermal overload relay. The integrated
protection electronic circuit breaker provides overload, phase loss, phase unbalance, and short
circuit protection. This circuit breaker offers high tripping precision and reliable operation. The two-
component solution, comprising of a circuit breaker and a contactor, saves installation time and is
unaffected by ambient temperature.
2）Integrated protection: Basic electronic type release for motor protection ENM
The ENM electronic trip unit allows for tighter tolerance trip times, as detailed in the table below.
Electronic type ENM 250 400 630 800
Setting current Ir=Inx 0.4-0.5-0.6-0.7-0.8-0.9-1.0, OFF
Overload
long-time delay 4、8、16,
7.2Ir Tripping time Ir(s) 4、8、16、24, Accuracy ±15%
protection Accuracy ±10%
Tripping level 5、10、20 5、10、20、30
Short circuit Setting current I sd=Ir x 5-6-8-9-10-11-12, OFF, Accuracy ±15%
short-time delay
protection Tripping time Tsd(ms) 100, Accuracy ±40
Short circuit Setting current Ir=Inx 151)
instantaneous
protection Max. trpping time (ms) 60
Phase unbalance/Phase failure Iunbal 30%-40%-50%-60%-70%-80%-90% (Phase failure)-OFF
Max. trip time of phase imbalance (s) 4-6-8-10, Accuracy ±20%
Tripping time of phase failure (s) 0.25, Accuracy ±20%
IrN=(0.5,1)xIn;I sdN=(5-6-8-9-10-11-12)IrN
Neutral line Setting current
IiN=15IrN, OFF
protection
Tripping time The same with the other three-phase poles

Note: 1）Setting current Isd<Ii (within tolerance).

3）The EMM electronic release offers all the protection functions of the ENM release, with additional
ground fault and locked-rotor protection. It has parameter setting functions., provides real-time
current display, protection parameter information display and fault information display.
Electronic type EMM 250 400 630 800
Protection current Ir=Inx 0.4~1.0, Stepping , OFF
Overload
4、8、16,
long-time delay 7.2Ir Tripping time Tr(s) 4、8、16、24, Accuracy ±10%
Accuracy ±10%
protection
Tripping level 5、10、20 5、10、20、30
Short circuit Setting current I sd=Ir x 4~12, Stepping1A , OFF, Accuracy ±15%
short-time delay
protection Tripping time Tsd(ms) 100, Accuracy ±40
Short circuit Protection current Ir=Inx 151)
instantaneous
protection Max. trpping time (ms) 60
Protection current I g=Inx 0.4-0.5-0.6-0.7-0.8-0.9-1.0 , OFF, Accuracy ±15%
Earth falt
protection 0.1-0.2-0.3-0.4, Accuracy ±20% or 40ms(higher
Tripping time (s)
value will be selected)
Phase unbalance/Phase failure Iunbal 30%-40%-50%-60%-70%-80%-90% (Phase failure)-OFF
Max. trip time of phase imbalance (s) 4-6-8-10, Accuracy ±10%
Tripping time of phase failure (s) 0.25, Accuracy ±20%
Locked-rotor current Ijam (3~10)Ir , Stepping1A, OFF(Defalut), Accuracy ±15%
Tripping time T jam (s) 1~30, Step size1s, Defalut 5, Accuracy ±10%
Neutral line Setting current IrN=(0.5,1)xIn, OFF;I sdN=(4~12)IrN;IiN=15IrN, OFF
protection Tripping time The same with the other three-phase poles

Note: 1）Setting current Isd<Ii (within tolerance).

 NM8N MCCB P- 013

6. Tripping curve
6.1 Thermal-magnetic type for power distribution

NM8N-125(16A,20A,25A,32A)

NM8N-125(40A,50A,63A)

NM8N-125(80A,100A,125A)
P- 014 MCCB NM8N

NM8N-250(125A,160A)

NM8N-250(180A)

NM8N-250(200A,225A,250A)
NM8N MCCB P- 015

NM8N-400(250A~400A)

NM8N-630(400A~500A)

NM8N-800(500A~800A)
 P- 016 MCCB NM8N

NM8N-1600(800A~1600A)

6.2 Magnetic type for motor protection

NM8N-125(16A~125A)

Maximum heat withstand capacity

NM8N-250(125A~250A)

Maximum heat withstand capacity

NM8N MCCB P- 017

NM8N-400(250A~400A)

NM8N-630(400A~500A)

NM8N-800(500A~800A)
 P- 018 MCCB NM8N

6.3 Electronic type for power distribution

EN Basic electronic type

EM Standard electronic type

 NM8N MCCB P- 019

6.4 Electronic type for motor protection

ENM Basic electronic type

EMM Standard electronic type

 P- 020 MCCB NM8N

7. Mounting of circuit breaker

7.1 Modes of down-lead

7.2 Modes of mounting

7.3 Safe distance

Unit (mm)
 NM8N MCCB P- 021

8. Overall and Mounting Dimensions

8.1 NM8N-125
NM8N-125 Front connection

Front connecting plate

27.5

25
54.5

Front connecting plate

Phase barrier

Unit (mm)
P- 022 MCCB NM8N

NM8N-125 Front connection (3P/4P)

27.5
54.5

Unit (mm)

NM8N-125 Rear connection (1P/2P)

Unit (mm)
 NM8N MCCB P- 023

NM8N-125 Rear connection (3P/4P)

Unit (mm)

NM8N-125 Plug-in front connection

Unit (mm)

NM8N-125 Plug-in rear connection

Unit (mm)
P- 024 MCCB NM8N

NM8N-125 DIN-rail mounting

Unit (mm)

NM8N-125 DIN-rail mounting (DIN-rail adapter is needed)

Unit (mm)

NM8N-125 Mechanical interlock

Unit (mm)
NM8N MCCB P- 025

NM8N-125 Terminal cover

Unit (mm)
 P- 026 MCCB NM8N

8.2 NM8N-250
NM8N-250 Front connection (1P/2P)

34

27
60
75

20.5
34.4

27
75.3
60

20.5

Unit (mm)

NM8N-250 Front connection (3P/4P)

34.4

34.4

27
75.3
60
75.3
60

20.5

Unit (mm)
 NM8N MCCB P- 027

NM8N-250 Rear connection (1P/2P)

Unit (mm)

NM8N-250 Rear connection (3P/4P)

Rear connection

Unit (mm)

NM8N-250 Plug-in front connection

Mounting plate

Unit (mm)
P- 028 MCCB NM8N

NM8N-250 Plug-in rear connection

Horizontal connection
Mounting plate

Unit (mm)

NM8N-250 DIN-rail mounting

Unit (mm)

NM8N-250 DIN-rail mounting (DIN-rail adapter is needed)

Unit (mm)
 NM8N MCCB P- 029

NM8N-250 Mechanical interlock

Unit (mm)

NM8N-250 Terminal cover

3P Short terminal cover 4P Short terminal cover

3P Long terminal cover 4P Long terminal cover Unit (mm)

 P- 030 MCCB NM8N

8.3 NM8N-400/630
NM8N-400/630 Front connection

A ≤400A 500A/630A
mm 27 28

Front connection Phase barrier

Unit (mm)

NM8N-400/630 Rear connection

Rear connection

Unit (mm)

NM8N-400/630 Plug-in front connection

Mounting plate

Unit (mm)
 NM8N MCCB P- 031

NM8N-400/630 Plug-in rear connection

Vertical connection

Horizontal connection

Mounting plate
Unit (mm)

NM8N-400/630 DIN-rail mounting

Unit (mm)

NM8N-400/630 Mechanical interlock

Unit (mm)
P- 032 MCCB NM8N

NM8N-400/630 Long terminal cover

Unit (mm)

NM8N-400/630 Short terminal cover

Unit (mm)
 NM8N MCCB P- 033

NM8N-400/630 Draw-out type

Unit (mm)

Dimension
Current Pole
L1 L2 L3 L4 L5 L6 L7 H1 H3 H4 H5 H6 W1 W2 d1
3P 342 313 207 312 30 6 143 280 77 21 35.5 17.5 45 214 11
In≤400A
4P 342 313 207 312 30 6 143 280 77 21 35.5 17.5 45 259 11
3P 342.5 314.5 210.5 313.5 30 8 143 280 77.5 21.5 35.5 17.5 45 214 11
In>400A
4P 342.5 314.5 210.5 313.5 30 8 143 280 77.5 21.5 35.5 17.5 45 259 11

DIN-rail mounting

installation dimension
Pole
A B d2
3P 90 143 6.5
4P 135 143 6.5

DIN-rail mounting

Rear connection

Installation floor

Front connection

Installation floor

Installation dimension of rear plate connection

Current
L8 W5 L9 L7 W4 d3 Pole
143 90 181 70 138 7 3P
In≤400A
143 135 181 70 182 7 4P
144.5 90 182.5 70 138 7 3P
In>400A
144.5 135 182.5 70 182 7 4P
L7=90 when it is front connection, the rest of dimensions are the same with rear connection
 P- 034 MCCB NM8N

8.4 NM8N-800
NM8N-800 Front connection (3P)

Unit (mm)
 NM8N MCCB P- 035

NM8N-800 Front connection (4P)

Unit (mm)

NM8N-800 Rear connection

Unit (mm)
P- 036 MCCB NM8N

NM8N-800 Mechanical interlock

Unit (mm)

NM8N-800 Short terminal cover

Unit (mm)
 NM8N MCCB P- 037

NM8N-800 Long terminal cover

3P Long terminal cover 4P Long terminal cover

Unit (mm)
P- 038 MCCB NM8N

NM8N-800 Draw-out type

212.5
Front connection

Rear connection

Unit (mm)

Dimension
Pole
L3 L4 L5 L6 L8 L10 H1 H3 H4 H5 W1 W2 d1
3P 275 445 485 10 141 40 270 61 42.5 62.5 65 281 13
4P 275 445 485 10 141 40 270 61 42.5 62.5 65 346 13

DIN-rail mounting

installation dimension
Pole
A B d2
3P 130 141 7
4P 195 141 7

Rear connection

Installation floor

Front connection

Installation floor

Installation dimension
Pole
L8 W5 L9 L7 W4 d3
3P 141 130 177 95 200 7
4P 141 195 177 95 265 7

L7=200 when it is front connection, the rest of dimensions

are the same with rear connection
 NM8N MCCB P- 039

8.5 NM8N-1600
NM8N-1600 Front connection (Manual type 3P)

In 800A,1000A,1250A 1600A
A 10mm 20mm

Unit (mm)

NM8N-1600 Front connection (Manual type 4P)

In 800A,1000A,1250A 1600A
A 10mm 20mm

Unit (mm)
P- 040 MCCB NM8N

NM8N-1600 Front connection (Motor type 3P)

Connection row In 800A,1000A,1250A 1600A

A 10mm 20mm

Unit (mm)

NM8N-1600 Front connection (Motor type 4P)

Connection row In 800A,1000A,1250A 1600A

A 10mm 20mm

Unit (mm)
 NM8N MCCB P- 041

8.6 NM8NL
NM8NL-125 Front connection

Connection row

Phase barrier

Unit (mm)
P- 042 MCCB NM8N

NM8NL-125 Rear connection

Unit (mm)

NM8NL-125 DIN-rail mounting

Unit (mm)
NM8N MCCB P- 043

NM8NL-250 Front connection

Unit (mm)

NM8NL-250 Rear connection

Unit (mm)
P- 044 MCCB NM8N

NM8NL-250 DIN-rail mounting

Unit (mm)

NM8NL-400/630 Front connection

Unit (mm)

A ≤400A 500A,630A

mm 27 28
 NM8N MCCB P- 045

NM8NL-400/630 Rear connection

Unit (mm)

NM8NL-400/630 DIN-rail mounting

Unit (mm)

8.7 NM8N Wiring diagram

NM8N-125 Cable connector

Unit (mm)

NM8N-125 Product center

NM8N-125 Product center
NM8N-125 Product center
Product center
MC21-M8 1hole CCT21-M8 1hole
P- 046 MCCB NM8N

NM8N-250 Cable connector

NM8N-250 Product center NM8N-250 Product center

NM8NL-250 Product center NM8NL-250 Product center

CCT22-M8 1hole MC22-M8 1hole

NM8N-250 Product center NM8N-250 Product center

NM8NL-250 Product center NM8NL-250 Product center Unit (mm)

MC22-M8 2hole MC22-M8 6hole

NM8N-630 Cable connector

Unit (mm)

NM8N-400/630 Product center NM8N-400/630 Product center NM8N-400/630 Product center

NM8NL-400/630 Product center NM8NL-400/630 Product center NM8NL-400/630 Product center

CCT23-M8 1hole MC23-M8 2hole MC23-M8 2hole

 NM8N MCCB P- 047

NM8N-800 Cable connector

NM8N-800 Product center

MC24-M8 2hole
Unit (mm)

NM8N-1600 Cable connector

Unit (mm)

NM8N-1600 Product center NM8N-1600 Product center

MC25-M8 4hole MC25-M8 3hole

 P- 048 MCCB NM8N

8.8 Wiring

NM8N-125 NM8N-250

Unit (mm)

NM8N-400/630 NM8N-800

Unit (mm)

NM8N-1600

Unit (mm)
 NM8N MCCB P- 049

9. Accessories characteristics and installation

The NM8N moulded case circuit breaker offers various accessory modules. For more details, please
refer to page P84.
9.1 AX Auxiliary contact
9.1.1 Function
A volt-free contact to provide remote indication of the circuit breaker's ON or OFF status.
9.1.2 Model description

AX 21- M8

Serial code:NM8N series

Frame size code:Auxiliary contacts are universal accessories

for each frame,with default as code 21

Auxiliary contact name code

9.1.3 Indication of circuit breaker status

Circuit breaker is at breaking status AX12 AX11

AX14
AX12 AX11
Circuit breaker is at making status
AX14

9.1.4 Electrical characteristics

Rated Rated current (A)

voltage (V) AC-15 DC-13
AC 110 5 —
AC 240 4 —
AC 415 2 —
DC 110 — 0.25
DC 220 — 0.25

9.1.5 Wiring diagram

AX11 QF Power supply

AX14
Making circuit

Breaking circuit
AX
P- 050 MCCB NM8N

9.2 AL Alarm contact

9.2.1 Function
It is mainly used to provide a signal when the load of the circuit breaker is overloaded, short-circuited
or undervoltage, or tripped.
A volt-free contact to provide remote indication that the circuit breaker has tripped due to:
Overload or short-circuit
Undervoltage
Residual current
Non-manual trips.
9.2.2 Model description

AL 21- M8

Serial code:NM8N series

Frame size code:Alarm contacts are universal accessories

for each frame,with default as code 21

Alarm contact name code

9.2.3 Indication of circuit breaker status

Circuit breaker is Normal AL12 AL11

AL14
AL12 AL11
Circuit breaker has tripped
AL14

9.2.4 Electrical characteristics

Rated Rated current (A)

voltage (V) AC-15 DC-13
AC 110 5 —
AC 240 4 —
AC 415 2 —
DC 110 — 0.25
DC 220 — 0.25

9.2.5 Wiring diagram

AL11 QF
Power supply
TRIP AL14

Making circuit

Normal Breaking circuit

AL12
 NM8N MCCB P- 051

9.3 SHT Shunt release

9.3.1 Function
Shunt releases operate based on electrical signals, enabling remote control of circuit breakers.
When a voltage between 70% and 110% of the rated control power supply voltage is applied to its
terminals, the shunt release triggers the circuit breaker to open.
9.3.2 Model description

SHT 21- M8 AC48V

Rated voltage: AC48V/110V/220-240V/380-415V;

DC24V/110-120V/220V

Series code:NM8N series

Frame code: 21 for 125 frame; 22 for 250/400/630 frame;

24 for 800 frame; 25 for 1600 frame

Shunt release code

9.3.3 Electrical characteristics

Power consumption (W)

Frame size
AC48V AC110V AC220-240V AC380-415V DC24V DC220V

125A 2.2 2.2 2 2.5 2.5 2

250/400/630A 2.3 2.5 2.2 2.5 2.2 2.5

800A 2.3 2.5 2.2 2.5 2.2 2.5

1600A 110 195 480 560 230 160

9.3.3 Action characteristics

The shunt release can be powered for extended periods. Response time: pulse type≥20ms,≤60ms

9.3.5 Wiring diagram

Note: When using a rated control power supply voltage of DC24V for the shunt release, the
maximum length of the copper wire (each of the two wires) must meet the requirements outlined
in the following table:

Conductor cross-sectional area

1.5mm2 2.5mm2
Rated control
supply voltageUs(DC24V)
100%Us 150m 250m

85%Us 100m 160m

P- 052 MCCB NM8N

9.4 UVT Under-voltage release

9.4.1 Function
Undervoltage releases operate based on electrical signals, enabling remote control of circuit
breakers to protect electrical equipment. When the power supply voltage at it terminals is too low, the
undervoltage release triggers the circuit breaker to open.
Undervoltage Trip (70% - 35% of rated control supply voltage):
If the supply voltage drops to between 70% and 35% of the rated control supply voltage, the
undervoltage release triggers the circuit breaker to open.
Guaranteed Closure (≥ 85% of rated control supply voltage):
Once the supply voltage returns to a level that equals or exceeds 85% of the rated control supply
voltage of the undervoltage release, the circuit breaker should be allowed to close.
Prevention (Less than 35% of rated control supply voltage):
If the supply voltage drops below 35% of the rated control supply voltage of the undervoltage
release, it should prevent the circuit breaker from closing.
UVT 21- M8 AC48V

Rated voltage: AC48V;AC110V;AC220-240V;AC380-415V;

DC24V;DC48V;DC110-120V;DC220V

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250/400/630 frame;

24 for 800 frame; 25 for 1600 frame

Under-voltage release code

9.4.3 Electrical characteristics

Power consumption (W)

Frame size
AC48V AC110V AC220-240V AC380-415V DC24V DC48V DC110-120V DC220V

125A 1.6 1.6 2 3 1.2 1.6 2 2.2

250/400/630A 1.5 1.5 2.2 3 0.8 1.5 2 2.5

800A 1.5 1.5 2.2 3 0.8 1.5 2 2.5

1600A 2.6 2.2 1.7 0.7 2.8 2.5 2.2 1.8

9.4.4 Wiring diagram

Under-voltage release
 NM8N MCCB P- 053

9.5 MOD Motor-driven mechanism

9.5.1 Function
This system is suitable for remotely closing, opening, and re-closing circuit breakers, making it ideal
for both long-distance operations and automation applications.
A: Protection level: IP40
Reliable insulation;
With isolation function indication;
O (open), I (closed) and free trip 3 position indications;
Circuit breaker free trip
Manually or automatically operated circuit breakers for closing and opening.
B: manul operation
Pull the "manul/auto" switch to the manual position and turn the operation handle to switch on and
off the circuit breaker.
C: automatic operation
Pull the "manul/auto" switch to the automatic position, and remotely press the "close or open" button
to switch on and off the circuit breaker.
D: Automatically switch on or off by pulse or self-holding signal control.
E: Only when the control voltage is ≥ 85% Un and ≤ 110% Un can the circuit breaker be reliably
switched on and off.

9.5.2 Model description

MOD 21- M8 AC110/DC110-120V

Rated voltage: AC110/DC110-120V;AC220-240V/DC220V;

AC380-415V;DC24V

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame; 24 for 800 frame; 25 for 1600 frame

Motor-driven mechanism code

Note: The 1600A frame motor-driven mechanism is assembled in the factory and is suitable for
electronic circuit breakers and disconnectors based on the internal structure/configuration of the
circuit breaker.
 P- 054 MCCB NM8N

9.5.3 Electrical characteristics

Frame Operational Rated Life Power Action Making Breaking Minimum duration of
size Type operational voltage (CO recycle) consumption current duration duration ON(OFF) signal pulse

AC110V/DC110 ≥3
150
AC220-240V
150
125A MOD 21-M8 DC220V 10000 ≤500ms ≤500ms 300ms
150 ≥4
AC380-415V
100
DC24V

AC110V/DC110 ≥3
150
AC220-240V
150
250A MOD 22-M8 DC220V 10000 ≤500ms ≤500ms 300ms
150 ≥4
AC380-415V
100
DC24V

AC110V/DC110 ≥3
300
AC220-240V
300
400/630A MOD 23-M8 DC220V 8000 ≤1000ms ≤1000ms 300ms
300 ≥8
AC380-415V
190
DC24V

AC110V/DC110 ≥3
300
AC220-240V
300
800A MOD 24-M8 DC220V 4000 ≤1000ms ≤1000ms 300ms
300 ≥8
AC380-415V
190
DC24V

9.5.4 Wiring diagram

 NM8N MCCB P- 055

9.5.5 Installation dimension drawing

Overall and mounting dimension of MOD21-M8

Overall dimension of MOD22-M8

P- 056 MCCB NM8N

Mounting dimension of MOD22-M8

Overall and mounting dimension of MOD23-M8

 NM8N MCCB P- 057

Overall and mounting dimension of MOD24-M8

 P- 058 MCCB NM8N

9.6 SRH Economic extended rotary handle

9.6.1 Function
A unique design and transmission structure enable the circuit breaker to close, open, and reclose by
rotating the handle.
Protection degree: IP30
With isolation funtion indication;
O (open), I (closed) and free trip 3 position indications;
The circuit breaker can be locked in the OFF position using 1 to 3 padlocks with a diameter of
5 to 8mm. This prevents the circuit breaker from closing and ensures the switch cabinet cannot be
opened.
The rotary handle features an integrated door-interlock function that prevents the cabinet door
from opening when the switch is in the ON position. In emergency situations, the cabinet door can be
opened using the emergency unlocking device located on the handle.

9.6.2 Model description

SRH 21- M8 3P

Number of poles: 3P; 4P (only applicable to 125, 250 frames);400A and

above frames have no code

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame; 24 for 800 frame; 25 for 1600 frame

Economic extended rotary handle code

Note: default length of shaft is 150mm

9.6.3 Installation dimension drawing

Overall and mounting dimension of SRH21-M8

 NM8N MCCB P- 059

Overall and mounting dimension of SRH22-M8

Overall and mounting dimension of SRH23-M8

P- 060 MCCB NM8N

Overall and mounting dimension of SRH24-M8

Overall and mounting dimension of SRH25-M8

 NM8N MCCB P- 061

9.7 DRH Direct rotary handle

9.7.1 Function
A unique design and transmission structure enable the circuit breaker to be closed, opened, and
reclosed by rotating the handle.
Protection degree: IP40
Reliable insulation;
With isolation function indication;
O (open), I (closed) and free trip 3 position indications;
The circuit breaker can be locked in the OFF position through 1~3 padlocks with a diameter of
5~8mm.
(Padlock user prepared)

9.7.2 Model description

DRH 21- M8 T

Circuit breaker type: T: Thermal magnetic circuit breaker, M: Magnetic

circuit breaker, SD: Switch disconnector; E: Electronic circuit breaker

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame;
Direct rotary handle code

9.7.3 Installation dimension drawing

Overall dimension of DRH21-M8

Overall dimension of DRH22-M8

P- 062 MCCB NM8N

Overall dimension of DRH23-M8

9.8 ERH Extended rotary handle

9.8.1 Function
A unique design and transmission structure enable the circuit breaker to close, open, and reclose by
rotating the handle.
Protection degree: IP50
Reliable insulation;
With isolation funtion indication;
O (open), I (closed) and free trip 3 position indications;
When the switch cabinet door is opened, the setting value of the circuit breaker release can be
set;
When the switch cabinet door is opened, it can prevent the circuit breaker from closing;
The circuit breaker can be locked in the OFF position using 1 to 3 padlocks with a diameter of
5 to 8mm. This prevents the circuit breaker from closing and ensures the switch cabinet cannot be
opened.
(Padlock user prepared) can prevent the switch cabinet door from opening at this time;
The rotary handle features an integrated door-interlock function that prevents the cabinet door
from opening when the switch is in the ON position. In emergency situations, the cabinet door can be
opened using the emergency unlocking device located on the handle.

9.8.2 Model description

DRH 21- M8 T

Circuit breaker type: T: Thermal magnetic circuit breaker, M: Magnetic

circuit breaker, SD: Switch disconnector; E: Electronic circuit breaker

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame;

Extended rotary handle code

Note: default length of shaft is 500mm

 NM8N MCCB P- 063

9.8.3 Installation dimension drawing

Overall and mounting dimension of ERH21-M8

Overall and mounting dimension of ERH22-M8

P- 064 MCCB NM8N

9.9 LHD Extended handle

9.9.1 Function
With a unique design, the circuit breaker can be closed, opened and reclosed by rotating the handle.
It is only applicable to 1600A.

9.9.2 Model description

LHD 25- M8

Series code:NM8N series

Frame size code: 25 for 1600 frame

Extended handle code

9.9.3 Overall dimension

 NM8N MCCB P- 065

9.10 KLK Locking system

9.10.1 Function
The locking system secures the circuit breaker in the open position.
It can accommodate 1 to 3 padlocks with a diameter ranging from 5 to 8 mm.
(Padlock user prepared)

9.10.2 Model description

KLK 21- M8

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame;
Extended handle code

9.11 MIT Mechanical interlock

9.11.1 Function
When used with two circuit breakers of the same housing dimensions, if one circuit breaker is closed,
the interlocking mechanism prevents the other circuit breaker from closing and keeps it in the open
state.
9.11.2 Model description

MIT 21- M8 3P

Poles: 3P;4P (It is only applicable to 25、250、400、630); 800 No code

for shell frame

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame; 24 for 800 frame

Mechanical interlock code

9.12 TCV Short terminal cover

9.12.1 Function
Prevents contact with the main circuit and can also be used to prevent short circuit between phases.
Protection degree: IP40
For voltages ≥ 500V, terminal covers must be fitted

9.12.2 Model description

TCV 21- M8 3P

Poles: 3P;4P

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame; 24 for 800 frame

Short terminal cover code

P- 066 MCCB NM8N

9.13 TCE Long terminal cover

9.13.1 Function
Prevents contact with the main circuit and can also be used to prevent short circuit between phases.
There are knock-out holes in front of the terminal cover to accommodate various lug cables and front
wiring.
Protection degree: IP40
For voltages ≥ 500V, terminal covers must be fitted

9.13.2 Model description

TCE 21- M8 3P

Number of poles: 3P;4P

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame; 24 for 800 frame

Long terminal cover code

9.14 FCP Front connection plate

9.14.1 Function
Install this accessory to provide the circuit breaker with flexible wiring capabilities. It increases pole
spacing at the inlet and outlet ends, enhancing electrical separation between adjacent poles and
improving line safety.

9.14.2 Model description

FCP 25- M8 3P(16001))

Number of poles: 1P/2P(only for 125A and 250 frames); 3P; 4P

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame; 25 for 1600 frame

Front connection plate code

Note1): Only applicable to 1600 frame, there are three specifications of 1000, 1250, 1600.

9.15 RCP Rear connection plate

9.15.1 Function
Install this accessory to provide the circuit breaker with flexible wiring capabilities. It enables wiring
from behind the board .

9.15.2 Model description

RCP 25- M8 2P

Number of poles: 1P/2P(only for 125A and 250 frames); 3P; 4P

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame; 24 for 800 frame

Rear connection plate code

 NM8N MCCB P- 067

9.16 CCT Cage clamp terminal

9.16.1 Function
Install this accessory to provide the circuit breaker with flexible wiring capabilities. It enables direct
connection to bare cables.
9.16.2 Model description
CCT 21- M8
CCT21/22-M8
Series code:NM8N series
Frame size code: 21 for 125 frame; 22 for 250 frame;
23 for 400/630 frame
Cage clamp terminal code
9.16.3 Wiring capacity

Serial No. Wiring capacity Terque

CCT21-M8 (2.5~75)mm2 8N·m
CCT23-M8 CCT22-M8 (10~120)mm2 10N·m
CCT23-M8 (120~240)mm2 35N·m

9.17 MC Cable connector

9.17.1 Function
This connector enables direct connection of bare wires and facilitate the connection of multiple wires
to the circuit breaker.
9.17.2 Model description
MC 25- M8(3) (12501))

Current specifications
Number of external holes: (1) 1 hole; (2) 2 holes; (3) 3 holes; (4) 4 holes;
(6) 6 holes
Series code:NM8N series
Frame size code: 21 for 125 frame; 22 for 250 frame;
23 for 400/630 frame; 24 for 800 frame; 25 for 1600 frame;

Cable connector code

Note1): Only available for 1600AF size MCCB and for ratings from 800A to 1250A.
9.17.3 Wiring capacity
Serial No. Wiring capacity Torgue Note
MC21-M8 (1) (16~95)mm2 10N·m 1 hole
MC22-M8 (1) (35~240)mm2 30N·m 1 hole
MC22-M8 (2) 2×(35~120)mm2 30N·m 2 holes
MC22-M8 (6) 6×(10~35)mm2 10N·m 6 holes
MC23-M8 (2) 2×(120~240)mm2 35N·m 2 holes
MC23-M8 (4) 4×95mm2 15N·m 4 holes
MC24-M8 (2) 2×240mm2 35N·m 2 holes
MC25-M8(800) (3) 3×(95~300)mm2 35N·m 3 holes
MC25-M8(1000/1250) (4) 4×(95~240)mm2 35N·m 4 holes

9.18 PIA Plug-in base

9.18.1 Function
This system allows for quick replacement of the circuit breaker without touching the connections at
the incoming and outgoing of the base.
The plug-in base can be pre-installed, making it convenient for future additions of circuit breakers.
When mounted through a panel, the device isolates the power circuits, acting as a barrier for the
connections of the plug-in base.

9.18.2 Model description

PIA 21F- M8 3P

Number of holes: 3P; 4P

Series code:NM8N series

Code of wiring method: F for front connection; B for rear connection

Frame size code: 21 for 125 frame; 22 for 250 frame;
23 for 400/630 frame;
Plug-in base code
P- 068 MCCB NM8N

9.19 PISD plug-in safety device

9.19.1 Function
This device is used together with the plug-in base to ensure that the circuit breaker trips automatically
if it is pulled out while closed.

9.19.2 Model description

PISD 21-M8 T

Circuit breaker type: T thermal magnetic circuit breaker; E electronic circuit

breaker
Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

23 for 400/630 frame;
Plug-in safety device code

9.20 DOB Withdrawable base

9.20.1 Function
This system allows for quick replacement of the circuit breaker without touching the connections at
the incoming and outgoing of the base.
The withdrawable base can be pre-installed, making it convenient for future additions of circuit
breakers.
The optional plug-in safety device can be used together to ensure that the circuit breaker trips
automatically if it is pulled out while closed.

9.20.2 Model description

DOB 23F- M8 3P(400A)1)

Number of poles: 3P; 4P

Series code:NM8N series

Code of wiring method: F for front connection; B for rear connection

Frame size code: 23 for 400/630 frame; 24 for 800 frame

Draw-out base code

Note1): DOB23 is suitable for 400/630 housings. There are two specifications of 400 and 630.

9.21 DRA DIN-rail adapter

9.21.1 Function
This accessory enables the circuit breaker to be mounted on a 35mm DIN rail.
9.21.2 Model description

DRA 21-M8 3P

Number of poles: 3P; 4P

Series code:NM8N series

Frame size code: 21 for 125 frame; 22 for 250 frame;

DIN-rail adapter code

 NM8N MCCB P- 069

9.22 COMA Communication module

9.22.1 Function
The COMA communication module is an interface that facilitates communication between the MCCB
with electronic trip unit and the bus system, performing both communication and relay control output.
Utilizing the Modbus-RTU communication protocol, this module easily connects with a fieldbus master
device to achieve up to four remote functions.
The technical parameters are as follows:
Rated voltage: AC230V or DC24V (error range ± 15%)
Communication type: RS485 (Modbus-RTU protocol)
Contact capacity: AC250V / 3A; DC30V / 3A
Transmission media: shielded twisted pair
Transmission distance: 1.2km (using category A shielded twisted pair)
Working status indication: LED indication
Number of stations: 1 station
9.22.2 Model description

COMA 22- M8 DC24V 0.5m

Cable length
Rated voltage: AC230V, DC24V

Series code:NM8N series

Frame code: 22 is a universal accessory for electronic molded case circuit
breakers
Communication module code

9.22.3 Communication solution

Achievable
Solutions Required products and accessories Note
function
NM8N basic or standard electronic molded
Remote
Solution 1 case circuit breaker; 1. Read phase current
measure
COMA22-M8 communication module.
NM8N basic or standard electronic moulded
case circuit breaker;
1. Read phase current
Remote COMA22-M8 communication module;
2. Indicate circuit breaker
Solution 2 measure AX auxiliary contact (optional, indicating
position information (open,
Remote signal opening and closing status);
closed, trip status)
AL alarm contact (optional, indicating trip
status).
NM8N basic or standard electronic moulded
case circuit breaker; 1. Read phase current
Remote
COMA22-M8 communication module; 2. Indicate circuit breaker
measure
AX auxiliary contact (optional, indicating position information (open,
Solution 3 Remote signal
opening and closing status); closed, trip status)
Remote
AL alarm contact (optional, indicating trip 3. Control circuit breaker
control
status); opening and closing
MOD electric operation mechanism.

1. Read phase current

2. Indicate circuit breaker
NM8N standard electronic molded case circuit position information (open,
Remote
breaker; closed, trip status)
measure
COMA22-M8 communication module; 3. Control circuit breaker
Remote signal
AX auxiliary contact (optional, indicating opening and closing
Solution 4 Remote
opening and closing status); 4. Adjust the internal
control
AL alarm contact (optional, indicating trip parameter settings of the
Remote
status); controller (only for standard
adjustment
MOD electric operation mechanism. specifications. For details,
please refer to the
communication protocol).
P- 070 MCCB NM8N

9.23 PSU battery box

9.23.1 Function
Provide DC 9V power for the standard (liquid crystal) controller for users to view, set and modify
controller parameters, when current under 0.4In. The batteries inside box are changeble.
Output voltage: DC 9V
Continuous power supply time: 7 hours

9.23.2 Model description

PSU 22-M8

Series code:NM8N series

Frame size code: 22 is a universal accessory for standard (liquid crystal)

electronic molded case circuit breakers

Battery box code

9.24 Phase barrier

9.24.1 Function
Guarantees phase-to-phase insulation safety and prevents phase-to-phase short circuit.

9.24.2 Model description

PHS 21-M8

Series code:NM8N series

Shell code: 21 for 125 frame; 22 for 250 frame; 23 for 400/630 frame;
24 for 800 frame; 25 for 1600 frame

Phase barrier code, standard accessory

 NM8N MCCB P- 071

9.25 Installation diagram of internal accessories

Left ON Right
Mounting and wiring mode
Handle OFF
Accessory name
NM8N-125, 250 NM8N-400, 630
NM8N-800 NM8N-1600 NM8N-1600 MOD
NM8NL-125, 250 NM8NL-400, 630

3P, 4P 3P, 4P 3P, 4P 3P, 4P 3P, 4P

No accessory

Alarm contact

Auxiliary contact

Shunt release

Under-voltage release

Shunt release
Auxiliary contact

Auxiliary contact
Under-voltage telease

Shunt release
Alarm contact

Auxiliary contact
Alarm contact

Under-voltage release
Alarm contact

Shunt release
Auxiliary contact, alarm
Auxiliary contact
alarm contact
Under-voltage release

■-Shunt release ▲-Under-voltage release ○-Auxiliary contact ●-Alarm contact

Note: a. NM8N-125, 250, 400, 630, 800 cannot be eqipped with undervoltage release and shunt release at the same time;
b. NM8N-125, 250 3P/4P can be equipped with a maximum of 2 sets of auxiliary contacts; 1P has no internal accessories; 2P can be equipped
with a maximum of one auxiliary / alarm contact at the same time;
c. NM8N-400, 630 can install up to 3 sets of auxiliary contacts;
d. NM8N-800 can be eqipped with up to 4 auxiliary contacts;
e. NM8N-1600 MOD can be equipped with a maximum of 3 sets of auxiliary contacts, and can simultaneously install undervoltage release and
shunt release;
f. NM8N series can only be equipped with one alarm contact.
 P- 072 MCCB NM8N

10. Technical Supplement

10.1 DC application wiring method

Solutions Unipolar grounding system Ungrounded system

Circuit diagram

maximum short-circuit
Fault A Fault A has no effect
current Isc

maximum short-circuit maximum short-circuit

Impact of falt Fault B Fault B
current Isc current Isc

Fault C has no effect Fault C has no effect

≤DC500V

Note: Note:
1. The upper and lower lines can be used, here the 1. Both the upper and lower lines can be used, here the
following lines are taken as an example. following lines are taken as an example; 2. Make sure
that the installation method does not cause a secondary
ground fault.

DC500~750V

Note: Note:
1. The upper and lower lines can be used, here the 1. Both the upper and lower lines can be used, here the
following lines are taken as an example. following lines are taken as an example; 2. Make sure
that the installation method does not cause a secondary
ground fault.

DC750~1000V

Note:
1. The upper and lower lines can be used, here the
following lines are taken as an example.
 NM8N MCCB P- 073

10.2 NM8N power loss table

Fixed circuit breaker
Rated current Power loss
Release type Model resistance loss per pole
(A) per pole (W)
mΩ
16 8.8 2.3
20 8.8 3.5
25 5.2 3.3
32 4.5 4.6
40 2.6 4.2
NM8N-125
50 1.8 4.5
63 1.7 6.7
80 1.3 8.3
100 0.88 8.8
125 0.8 12.5
125 0.7 10.9
160 0.55 14.1
180 0.55 17.8
NM8N-250
200 0.55 22.0
Thermal 225 0.4 20.3
magnetic 250 0.4 25.0
250 0.35 21.9
315 0.25 24.8
NM8N-400
350 0.25 30.6
400 0.15 24.0
400 0.15 24.0
NM8N-630
500 0.12 30.0
500 0.08 20.0
630 0.08 31.8
NM8N-800
700 0.08 39.2
800 0.08 51.2
800 0.08 51.2
1000 0.08 80.0
NM8N-1600
1250 0.04 62.5
1600 0.04 102.4
32 0.8 0.8
63 0.4 1.6
NM8N-250 100 0.4 4.0
160 0.4 10.2
250 0.4 25.0
250 0.15 9.4
NM8N-400
400 0.15 24.0
Electronic
400 0.15 24.0
NM8N-630
630 0.12 47.6
NM8N-800 800 0.08 51.2
800 0.08 51.2
1000 0.08 80.0
NM8N-1600
1250 0.04 62.5
1600 0.04 102.4
63 0.8 3.2
NM8NSD-125 100 0.8 8.0
125 0.8 12.5
125 0.4 6.3
160 0.4 10.2
Switch NM8NSD-250
200 0.4 16.0
disconnector
250 0.4 25.0
250 0.15 9.4
NM8NSD-400
400 0.15 24.0
NM8NSD-630 630 0.12 47.6
NM8NSD-800 800 0.08 51.2
 P- 074 MCCB NM8N

10.3 NM8N thermal magnetic circuit breaker rated operational current and temperature compensation coefficient table

Ambient
temperature
-40℃ -35℃ -25℃ -15℃ -5℃ 0℃ +10℃ +20℃ +30℃ +40℃ +50℃ +60℃ +70℃
Rated current

16A 22.5 22 20.5 20 19.5 19 18.5 17.5 17 16 15 14.5 14

20A 28 27.5 26.5 25.5 24.5 24 23 22 21 20 19.5 18.5 18

25A 35 34 33 32 30.5 30 28 27 26 25 24 22.5 22

32A 45 44 42 41 39 38 37 35 33 32 30.5 29 28

40A 56 55 53 51 49 48 46 44 42 40 37 33.5 29
NM8N-125
50A 70 68.5 66 64 61 60 57.5 55 52.5 50 47.5 45 40

63A 88 86.5 83 80 77 75 72 69 66 63 58.5 53 46

80A 112 110 106 102 98 96 92 88 84 80 74.5 67 56

100A 140 137 132 127 122 120 115 110 105 100 93 84 80

125A 175 172 165 159 153 150 144 137 131 125 116 105 91

125A 175 172 165 159 153 150 144 137 131 125 118 106 96

160A 224 220 212 204 196 192 184 176 168 160 152 136 120

180A 252 247 238 229 220 216 207 198 189 180 171 157 144
NM8N-250
200A 280 275 265 255 245 240 230 220 210 200 190 175 166

225A 315 309 300 288 276 270 259 247 236 225 213 196 180

250A 350 343 332 319 306 300 287 275 262 250 237 218 207

250A 350 343 332 319 306 300 287 275 262 250 237 225 212

315A 441 433 418 402 386 378 362 346 331 315 300 286 271
NM8N-400
350A 490 481 465 447 429 420 402 385 367 350 332 295 276

400A 560 550 530 510 490 480 460 440 420 400 380 360 320

250A 350 343 332 319 306 300 287 275 262 250 237 225 212

315A 441 433 418 402 386 378 362 346 331 315 300 286 271

NM8N-630 350A 490 481 465 447 429 420 402 385 367 350 332 295 276

400A 560 550 530 510 490 480 460 440 420 400 380 360 320

500A 700 687 662 637 612 600 575 550 525 500 450 406 360

500A 700 687 662 637 612 600 575 550 525 500 490 460 400

630A 882 866 836 804 772 756 724 693 661 630 580 530 490
NM8N-800
700A 980 962 927 892 857 840 805 770 735 700 670 645 575

800A 1120 1100 1060 1020 980 960 920 880 840 800 735 670 625

800A 1120 1100 1060 1020 980 960 960 920 840 800 760 696 640

1000A 1400 1375 1325 1275 1225 1200 1200 1150 1050 1000 950 870 800
NM8N-1600
1250A 1750 1718 1656 1594 1531 1500 1500 1437 1312 1250 1187 1088 1000

1600A 2240 2200 2120 2040 1960 1920 1960 1760 1680 1600 1520 1390 1280

Note:1) For a muiti-pole DC circuit breaker, if a 2m long standard wire is used in series, the derating factor above applies.
Note:2) When the DC jumper is connected in series, it needs to be further reduced based on the above table (except NM8NDC-1600). The specific
derating factor should be determined by users according to their different wiring methods. Derating by a factor of 0.8.
 NM8N MCCB P- 075

10.4 NM8N electronic circuit breaker rated operational current and temperature compensation coefficient table

Ambient
temperature
-25℃ -15℃ -5℃ 0℃ +10℃ +20℃ +30℃ +40℃ +50℃ +60℃ +70℃
Rated current

32A 32 32 32 32 32 32 32 32 32 32 32

63A 63 63 63 63 63 63 63 63 63 63 63

NM8N-250 100A 100 100 100 100 100 100 100 100 100 100 100

160A 160 160 160 160 160 160 160 160 160 160 160

250A 250 250 250 250 250 250 250 250 240 225 213

250A 250 250 250 250 250 250 250 250 250 250 250
NM8N-400
400A 400 400 400 400 400 400 400 400 380 360 340

250A 250 250 250 250 250 250 250 250 250 250 250

NM8N-630 400A 400 400 400 400 400 400 400 400 380 360 340

630A 630 630 630 630 630 630 630 630 600 570 540

630A 630 630 630 630 630 630 630 630 630 630 630
NM8N-800
800A 800 800 800 800 800 800 800 800 760 720 680

800A 800 800 800 800 800 800 800 800 800 800 800

1000A 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000
NM8N-1600
1250A 1250 1250 1250 1250 1250 1250 1250 1250 1250 1250 1250

1600A 1600 1600 1600 1600 1600 1600 1600 1600 1520 1440 1360

Note: Individual product specifications need to be derated at temperatures of 50°C and above. Refer to the provided table for parameters, and adjust Ir
to the corresponding setting.
For example: NM8N-250 EN 250 3P products are used at 70℃ . The product needs to be derated to 213A, and the Ir position is adjusted to 0.8In
position. The NM8N-250 EM 250 3P product is used at 70℃ .

10.5 Derating factor table for circuit breaker with residual current protection module

Model Derating factor

16A~63A 1

NM8N-125+NM8NL-125 80A~100A 0.9

125A 0.8

125A~180A 1
NM8N-250+NM8NL-250
200A~250A 0.9

32A、63A、100A、160A 1
NM8N-250+NM8NL-250 electronic type
250A 0.95

250A 1

NM8N-400+NM8NL-400 315A、350A 0.96

400A 0.93

250A 1
NM8N-400+NM8NL-400 electronic type
400A 0.95

400A 0.93
NM8N-630+NM8NL-630
500A 0.87

400A~500A 1
NM8N-630+NM8NL-630 electronic type
630A 0.90
 P- 076 MCCB NM8N

10.6 Derating factor table for circuit breakers with plug-in or draw-out accessories

Derating factor
Model
+Plug-in type +Economic draw-out type

16A-100A 1 /
NM8N-125
125A 0.95 /

125A-180A 1 /
NM8N-250
200A-250A 0.95 /

NM8N-250 32A、63A、100A、160A 1 /
electronic type 250A 0.95 /

NM8N-400 250A-400A 1 1
NM8N-400
250A-400A 1 1
electronic type
400A 1 1
NM8N-630
500A 0.95 1

NM8N-630 400A-500A 1 1
electronic type 630A 0.9 0.9

500-700A / 0.95
NM8N-800
800A / 0.9

NM8N-800 630A / 1
electronic type 800A / 0.9

10.7 NM8N Derating factor table for circuit breakers altitude

Altitude (m) 2000m 3000m 4000m 5000m

Rated operational current In 1×In 0.96×In 0.93×In 0.9×In

AC 690 550 480 420

Rated operational voltage Ue (V)
DC (4pole string) 1000 900 850 800

Rated insulation voltage Ui (V) 1000 930 870 800

Uimp = 8kV 2200 2050 1900 1770

AC
Uimp = 12kV 2550 2370 2200 2050
Dielectric properties (V)
Uimp = 8kV 3110 2892 2705 2488
DC
Uimp = 12kV 3600 3350 3110 2985

NM8N-125
NM8N-250 8 8 8 8
Rated insulation impulse voltage NM8N-1600
Uimp (kV) NM8N-400
NM8N-630 12 10 8 8
NM8N-800
 NM8N MCCB P- 077

10.8 Cascading (AC220/230/240V)

Upstream NM8N-125 NM8N-250 NM8N-400 NM8N-630 NM8N-800

Breaking C S Q H R C S Q H R C S Q H R C S Q H R C S Q H R
capacity
(kA rms) 36 50 70 100 150 36 50 70 100 150 36 50 70 100 150 36 50 70 100 150 36 50 70 100 150

Downstream Breaking capacity (kA rms)

NB1N 25 30 40 60 60 25 30 40 60 60 — — — — — — — — — — — — — — —

NB1H 30 40 50 65 65 30 40 50 65 65 — — — — — — — — — — — — — — —

NM8N-125C 50 60 80 100 50 60 80 100 50 60 80 100 50 60 80 100 50 60 80 100

NM8N125S 70 90 120 70 90 120 70 90 120 70 90 120 70 90 120

NM8N-125Q 90 140 90 140 90 140 90 140 90 140

NM8N-125H 150 60 150 150 150 150

NM8N-250C 50 70 80 100 50 60 80 100 50 60 80 100 50 60 80 100

NM8N-250S 90 120 70 90 120 70 90 120 70 90 120

NM8N-250Q 90 140 90 140 90 140 90 140

NM8N-250H 150 150 150 150

NM8N-400C 50 60 80 100 50 60 80 100 50 60 80 100

NM8N-400S 70 90 120 70 90 120 70 90 120

NM8N-400Q 90 140 90 140 90 140

NM8N-400H 150 150 150

NM8N-630C 50 60 80 100 50 60 80 100

NM8N-630S 70 90 120 70 90 120

NM8N-630Q 90 140 90 140

NM8N-630H 150 150

NM8N-800C 50 60 80 100

NM8N-800S 70 90 120

NM8N-800Q 90 140

NM8N-800H 150
 P- 078 MCCB NM8N

10.9 Cascading (AC380/400/415V)

Upstream NM8N-125 NM8N-250 NM8N-400 NM8N-630 NM8N-800

Breaking C S Q H R C S Q H R C S Q H R C S Q H R C S Q H R
capacity
(kA rms) 36 50 70 100 150 36 50 70 100 150 36 50 70 100 150 36 50 70 100 150 36 50 70 100 150

Downstream Breaking capacity (kA rms)

NB1N 20 25 25 25 25 20 25 25 25 25 — — — — — — — — — — — — — — —

NB1H 30 30 30 30 30 30 30 30 30 30 — — — — — — — — — — — — — — —

NM8N-125C 50 50 80 100 50 50 80 100 50 50 80 100 50 50 80 100 50 50 80 100

NM8N125S 70 90 120 70 90 120 70 90 120 70 90 120 70 90 120

NM8N-125Q 90 140 90 140 90 140 90 140 90 140

NM8N-125H 150 150 150 150 150

NM8N-250C 50 50 80 100 50 50 80 100 50 50 80 100 50 50 80 100

NM8N-250S 70 90 120 70 90 120 70 90 120 70 90 120

NM8N-250Q 90 140 90 140 90 140 90 140

NM8N-250H 150 150 150 150

NM8N-400C 50 50 80 100 50 50 80 100 50 50 80 100

NM8N-400S 70 90 120 70 90 120 70 90 120

NM8N-400Q 90 140 90 140 90 140

NM8N-400H 150 150 150

NM8N-630C 50 50 80 100 50 50 80 100

NM8N-630S 70 90 120 70 90 120

NM8N-630Q 90 140 90 140

NM8N-630H 150 150

NM8N-800C 50 50 80 100

NM8N-800S 70 90 120

NM8N-800Q 90 140

NM8N-800H 150
 NM8N MCCB P- 079

Note
 P- 080 MCCB NM8N

10.10 Selective protection

Upstream
NM8N-125 NM8N-250 NM8N-250 Electronic

Downstream In (A) 16 20 25 32 40 50 63 80 100 125 125 160 180 200 225 250 32 63 100 160 250

≤10 190 190 300 400 500 500 500 630 800 1000 T T T T T T 400 500 1000 T T

16 300 400 500 500 500 630 800 1000 T T T T T T 400 500 1000 T T

20 500 500 500 630 800 1000 T T T T T T 500 1000 T T

NB1 25 500 500 630 800 1000 T T T T T T 500 1000 T T

Tripping currve:B/C 32 500 630 800 1000 2000 5000 T T T T 500 1000 T T

40 630 800 1000 2000 5000 T T T T 1000 T T

50 800 1000 2000 5000 T T T T 1000 T T

63 1000 2000 5000 T T T T 1000 T T

16 400 500 500 630 800 1000 1000 2500 2500 2500 2500 2800 500 1000 2500 2800

50 500 500 630 800 1000 1000 2500 2500 2500 2500 2800 500 1000 2500 2800

25 500 630 800 1000 1000 2500 2500 2500 2500 2800 500 1000 2500 2800

32 630 800 1000 1000 2500 2500 2500 2500 2800 1000 2500 2800

40 800 1000 1000 2000 2000 2500 2500 2800 1000 2000 2800
NM8N-125
50 1000 1000 2000 2000 2500 2500 2800 1000 2000 2800

63 1000 2000 2000 2500 2500 2800 2000 2800

80 2000 2000 2500 2500 2800 2000 2800

100 2500 2500 2800 2800

125 2500 2800 2800

125

160

180
NM8N-250
200

225

250

32 1000 2000 2800

63 2000 2800
NM8N-250
100 2800
Electronic
160

250

250

315
NM8N-400
350

400

NM8N-400 250
Electronic 400

250

315

NM8N-630 350

400

500

250
NM8N-630
400
Electronic
630

Note: 1) No content, meaning no selectivity.

Note: 2) The number "1000" indicates the selectivity limit for partial discrimination, which is the maximum fault current at which selectivity can be
maintained. For currents below 1000A, selectivity can be achieved. However, for fault currents above 1000A, both the upstream and
d downstream circuit breakers may operate simultaneously.
Note: 2) "T" indicates that full selectivity is maintained up to the rated short-circuit breaking capacity of the downstream circuit breaker.
 NM8N MCCB P- 081

NM8N NM8N
NM8N-630
NM8N-400 -400 NM8N-630 NM8N-800 -800 NM8N-1600 NM8N-1600 Electronic
Electronic
Electronic Electronic

250 315 350 400 250 400 250 315 350 400 500 250 400 630 500 630 700 800 800 800 1000 1250 1600 800 1000 1250 1600

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

T T T T T T T T T T T T T T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

3500 4000 5000 5000 3500 4000 5000 T 5000 T T T T T T T T T T T T T T

4000 5000 5000 4000 5000 T 5000 T T T T T T T T T T T T T T

5000 5000 5000 T 5000 T T T T T T T T T T T T T T

5000 5000 5000 T 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

2800 3500 4000 5000 2800 5000 2800 3500 4000 5000 T 2800 5000 T T T T T T T T T T T T T T

4000 5000 5000 4000 5000 T 5000 T T T T T T T T T T T T T T

5000 5000 5000 T 5000 T T T T T T T T T T T T T T

5000 5000 6000 9500 9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

6000 9500 9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

5000 5000 6000 5000 9500 9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

5000 5000 6000 9500 9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

6000 9500 9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 9500 9500 9500 9500 9500 12500 16000 9500 9500 12500 16000

5000 5000 6000 5000 9500 9500 9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 9500 9500 9500 9500 12000 15000 19000 9500 12000 15000 19000

9500 12500 16000 9500 12500 16000

 P- 082 MCCB NM8N

11. Ordering notice

11.1 Quick selection of circuit breaker
11.1.1 Quick selection of power distribution and motor protection circuit breakers1)

NM8N 250 S TM 125 4C OTHER

Frame Breaking Special

Circuit breaker Release type Rated current(A) Poles
current(A) capacity code requirement

TM/M EN/EM/ENM/EMM

M: Magnetic for 125 : 16, 20, 25, 1P : One pole

3 2, 4 0 , 5 0 , 6 3 ,
motor protection — 2P : Two-pole
80,
TM: Thermal 100, 125 3P : Three-pole
Magnetic for 4B : Four-pole2)
Distribution 4C : Four-pole2)
25 0 : 125, 16 0,
Protection 250 : 32, 63, 100
18 0 , 2 0 0 , 2 2 5 ,
EN: Electronic 160, 250
125 C : 36kA 250
Basic for
250 S : 50kA
Distribution
400 Q : 70kA
Protection
630 H : 100kA 400 : 250, 315
EM: Electronic 400 : 250, 400
800 R : 150kA 350, 400
Standard for
Distribution
Protection 3P : Three-pole
ENM: Electronic 630 : 400, 500 630 : 400, 630 4B : Four-pole2)
NM8N Standard 4C : Four-pole2)
moulded case for Motor
circuit breaker Protection
800 : 500, 630
800 : 630, 800
700, 800

TM: Thermal TM/EN/EM

Magnetic for
Distribution
Protection
EN: Electronic
MOD DC1103)
S : 50kA Basic for 3P : Three-pole 3)
2) MOD DC220
1600 Q : 70kA Distribution 4B : Four-pole 3)
MOD AC230
H : 100kA Protection 1600 : 800, 1000, 1250, 1600 4C : Four-pole2)
MOD AC4003)
EM: Electronic
Standard for
Distribution
Protection

Note: 1) For unique requirements beyond the standard technical specifications, please contact our sales or technical department for special order
processing. When placing an order, the circuit breaker body and accessories should be listed separately. If factory assembly of the body and
accessories should be listed separately. If factory assembly of the body and accessories is required, specify this in the order; otherwise, they will
be shipped separately. Note that motor protection is applicable only to 3P/4P configurations.
2)
4B: Neutral poles without protection, can be operated with other three poles;
4C: Neutral poles with protection, can be operated with other three poles.
3)
Only NM8N-1600 has motor type
 NM8N MCCB P- 083

11.1.2 Quick selection of DC circuit breaker

NM8N

DC 250 S TM 125 2P OTHER

Breaking Rated Special

Current type Frame current(A) Release type Poles
capacity code current(A) requirement

125 : 16, 20, 25,

32, 40, 50, 63, 80,
100, 125

2 5 0 : 12 5 , 16 0 ,
18 0, 2 0 0, 2 2 5,
B : 25kA 250
125
C : 36kA TM: Thermal 1P : One pole1)
250
S : 50kA Magnetic 2P : Two-pole1)
400
Q : 70kA for Distribution 3P : Three-pole
630 400 : 250, 315
H : 100kA Protection 350, 400 4P : Four-pole
800

630 : 400, 500

DC : Direct current

800 : 500, 630

700, 800

TM: Thermal
B : 25kA Magnetic 1600 : 800, 1000, 3P : Three-pole
1600
C : 36kA for Distribution 1250, 1600 4P : Four-pole
Protection

Note: 1) 1P / 2P is limited to 125 and 250 frame products.

 P- 084 MCCB NM8N

11.1.3 Quick selection of switch disconnector

NM8N

SD 250 AC 125 2P OTHER

Switch Special
Frame current(A) Release type Rated current(A) Poles
disconnector requirement

125 : Default
125 250 : Default
250
SD : Switch AC: Alternating current 2P : Two-pole1)
400 400 : Default
disconnector DC: Direct current 3P : Three-pole
630
800 : Default 4P : Four-pole
800
1600 : 800, 1000,1250, 1600

Note: 1) 2P is only for 125 and 250 frame products.

 NM8N MCCB P- 085

Note
 P- 086 MCCB NM8N

11.2 NM8N accessory models selection table

Accessory type Code Specification NM8N-125 NM8N-250
Universal AX21-M8
Auxiliary contact AX
Neutral AX21-M8 N
Universal AL21-M8
Alarm contact AL
Neutral AL21-M8 N
AC48V SHT21-M8 AC48V SHT22-M8 AC48V
AC110V SHT21-M8 AC110V SHT22-M8 AC110V
AC220-240V SHT21-M8 AC220-240V SHT22-M8 AC220-240V
Shunt release SHT
AC380-415V SHT21-M8 AC380-415V SHT22-M8 AC380-415V
DC24V SHT21-M8 DC24V SHT22-M8 DC24V
DC220V SHT21-M8 DC220V SHT22-M8 DC220V
AC48V UVT21-M8 AC48V UVT22-M8 AC48V
AC110V UVT21-M8 AC110V UVT22-M8 AC110V
AC220-240V UVT21-M8 AC220-240V UVT22-M8 AC220-240V
AC380-415V UVT21-M8 AC380-415V UVT22-M8 AC380-415V
Under-voltage release UVT
DC24V UVT21-M8 DC24V UVT22-M8 DC24V
DC48V UVT21-M8 DC48V UVT22-M8 DC48V
DC110-120V UVT21-M8 DC110-120V UVT22-M8 DC110-120V
DC220V UVT21-M8 DC220V UVT22-M8 DC220V
AC110/DC110-120V MOD21-M8 AC110/DC110-120V MOD22-M8 AC110/DC110-120V
AC220-240/DC220V MOD21-M8 AC220-240V/DC220V MOD22-M8 AC220-240V/DC220V
Motor-driven mechanism MOD
AC380-415V MOD21-M8 AC380-415V MOD22-M8 AC380-415V
DC24V MOD21-M8 DC24V MOD22-M8 DC24V
Economic extended 3P SRH21-M8 3P SRH22-M8 3P
SRH
rotart handle 4P SRH21-M8 4P SRH22-M8 4P
Thermal magnetic (T) DRH21-M8 T DRH22-M8 T
Magnetic (M) DRH21-M8 M DRH22-M8 M
Direct rotary handle DRH
Electronic (E) / DRH22-M8 E
Switch disconnector (SD) DRH21-M8 M DRH22-M8 SD
Thermal magnetic (T) ERH21-M8 T ERH22-M8 T
Magnetic (M) ERH21-M8 M ERH22-M8 M
Extended rotary handle ERH
Electronic (E) / ERH22-M8 E
Switch disconnector (SD) ERH21-M8 M ERH22-M8 SD
Extended rotary handle LHD 3P/4P / /
Locking system KLK KLK21-M8 KLK22-M8
3P MIT21-M8 3P MIT22-M8 3P
Mechanical interlock MIT
4P MIT21-M8 4P MIT22-M8 4P
3P TCV21-M8 3P TCV22-M8 3P
Short terminal cover TCV
4P TCV21-M8 4P TCV22-M8 4P
3P TCE21-M8 3P TCE22-M8 3P
Long terminal cover TCE
4P TCE21-M8 4P TCE22-M8 4P
1P FCP21-M8 1P FCP22-M8 1P
2P FCP21-M8 2P FCP22-M8 2P
Front connection plate FCP
3P FCP21-M8 3P FCP22-M8 3P
4P FCP21-M8 4P FCP22-M8 4P
1P RCP21-M8 1P RCP22-M8 1P
2P RCP21-M8 2P RCP22-M8 2P
Rear connection plate RCP
3P RCP21-M8 3P RCP22-M8 3P
4P RCP21-M8 4P RCP22-M8 4P
Cage clamp terminal CCT 1hole CCT21-M8 CCT22-M8
1hole MC21-M8(1) MC22-M8(1)
2hole / MC22-M8(2)
Cable connector MC 3hole / /
4hole / /
6hole / MC22-M8(6)
3P Front connection PIA21F-M8 3P PIA22F-M8 3P
4P Front connection PIA21F-M8 4P PIA22F-M8 4P
Plug-in base PIA
3P Rear connection PIA21B-M8 3P PIA22B-M8 3P
4P Rear connection PIA21B-M8 4P PIA22B-M8 4P
Thernal magnetic (T) PISD21-M8 T PISD22-M8 T
Plug-in safety device PISD
Electronic (E) / PISD22-M8 E
3P Front connection / /
4P Front connection / /
Withdrawable base DOB
3P Rear connection / /
4P Rear connection / /

3P DRA21-M8 3P DRA22-M8 3P
DIN-rail adapter DRA
4p DRA21-M8 4P DRA22-M8 4P

/ COMA22-M8 DC24V 0.5m

DC24V / COMA22-M8 DC24V 1.5m
/ COMA22-M8 DC24V 3m
Communication module COMA
/ COMA22-M8 AC230V 0.5m
AC230V / COMA22-M8 AC230V 1.5m
/ COMA22-M8 AC230V 3m
Battery box PSU / PSU22-M8
Phase barrier PHS PHS21-M8 PHS22-M8
 NM8N MCCB P- 087

NM8N-400 NM8N-630 NM8N-800 NM8N-1600

AX21-M8
AX21-M8 N
AL21-M8
AL21-M8 N
SHT22-M8 AC48V SHT24-M8 AC48V SHT25-M8 AC48V
SHT22-M8 AC110V SHT24-M8 AC110V SHT25-M8 AC110V
SHT22-M8 AC220-240V SHT24-M8 AC220-240V SHT25-M8 AC220-240V
SHT22-M8 AC380-415V SHT24-M8 AC380-415V SHT25-M8 AC380-415V
SHT22-M8 DC24V SHT24-M8 DC24V SHT25-M8 DC24V
SHT22-M8 DC220V SHT24-M8 DC220V SHT25-M8 DC220V
UVT22-M8 AC48V UVT24-M8 AC48V UVT25-M8 AC48V
UVT22-M8 AC110V UVT24-M8 AC110V UVT25-M8 AC110V
UVT22-M8 AC220-415V UVT24-M8 AC220-240V UVT25-M8 AC220-240V
UVT22-M8 AC380-415V UVT24-M8 AC380-415V UVT25-M8 AC380-415V
UVT22-M8 DC24V UVT24-M8 DC24V UVT25-M8 DC24V
UVT22-M8 DC48V UVT24-M8 DC48V UVT25-M8 DC48V
UVT22-M8 DC110-120V UVT24-M8 DC110-120V UVT25-M8 DC110-120V
UVT22-M8 DC220V UVT24-M8 DC220V UVT25-M8 DC220V
MOD23-M8 AC110/DC110-120V MOD24-M8 AC110/DC110-120V MOD25-M8 AC110/DC110-120V
MOD23-M8 AC220-240V/DC220V MOD24-M8 AC220-240V/DC220V MOD25-M8 AC220-240V/DC220V
MOD23-M8 AC380-415V MOD24-M8 AC380-415V MOD25-M8 AC380-415V
MOD23-M8 DC24V MOD24-M8 DC24V MOD25-M8 DC24V

SRH23-M8 SRH24-M8 SRH25-M8

DRH23-M8 T / /
DRH23-M8 M / /
DRH23-M8 E / /
DRH23-M8 SD / /
ERH23-M8 T / /
ERH23-M8 M / /
ERH23-M8 E / /
ERH23-M8 SD / /
/ / LHD25-M8
KLK23-M8 / /
MIT23-M8 3P /
MIT24-M8
MIT23-M8 4P /
TCV23-M8 3P TCV24-M8 3P /
TCV23-M8 4P TCV24-M8 4P /
TCE23-M8 3P TCE24-M8 3P /
TCE23-M8 4P TCE24-M8 4P /
/ / /
/ / /
FCP23-M8 3P / FCP25-M8 3P
FCP23-M8 4P / FCP25-M8 4P
/ / /
/ / /
RCP23-M8 3P RCP24-M8 3P /
RCP23-M8 4P RCP24-M8 4P /
CCT23-M8 / /
/ / /
MC23-M8(2) MC24-M8(2) /
/ / MC25-M8(3)(800)
MC23-M8(4) / MC25-M8(4)(1000/1250)
/ / /
PIA23F-M8 3P / /
PIA23F-M8 4P / /
PIA23B-M8 3P / /
PIA23B-M8 4P / /
PISD23-M8 T PISD24-M8 T /
PISD23-M8 E PISD24-M8 E /
DOB23F-M8 3P(400A) DOB23F-M8 3P(630A) DOB24F-M8 3P /
DOB23F-M8 4P(400A) DOB23F-M8 4P(630A) DOB24F-M8 4P /
DOB23B-M8 3P(400A) DOB23B-M8 3P(630A) DOB24B-M8 3P /
DOB23B-M8 4P(400A) DOB23B-M8 4P(630A) DOB24B-M8 4P /
/
/
/ / /
/ / /
COMA22-M8 DC24V 0.5m
COMA22-M8 DC24V 1.5m
COMA22-M8 DC24V 3m
COMA22-M8 AC230V 0.5m
COMA22-M8 AC230V 1.5m
COMA22-M8 AC230V 3m
PSU22-M8
PHS23-M8 PHS24-M8 PHS25-M8