Example of curve reading

Example 1 – XT3N 225 t [s]

104

Trip curves for distribution (thermal magnetic trip unit)

Let us consider an XT3N TMF In = 225A circuit-breaker. 103
According to the conditions the overload is found in; i.e., with
the circuit-breaker at thermal regime or not, thermal protection
tripping varies considerably. 102 152.7 s
For example, for an overload current 3xI1, the trip time is
40.2 s
between 152,7s and 40,2s for cold tripping and between 40,2s
and 6,9s for hot tripping. 10
4 For fault current values higher than 225A. Tthe circuit-breaker
6.9 s

trips with the instantaneous magnetic protection I3.

1

3 x I1
10-1

10-2
10-1 1 10 102
x I1

I2t [106 A2s]

Example 2 – XT2H 125 10

Specific let-through energy curves

This figure figure shows a sample graph of the specific let-
through energy of the XT2H 125 circuit-breaker at a voltage of
220/230V.
The prospective symmetrical short-circuit current is indicated 1

on the abscissas, whereas the values of the specific let-through

energy expressed in A2s are shown on the ordinates.
The circuit-breaker lets through a value of I 2t equal to 0, 42 ·
10^6 · A2s relative to a short-circuit current of 14kA.
14 kA
10 -1

10 -2
1 10 10 2 10 3
x Irms [kA]

4/2 SACE Tmax XT UL/CSA | US Technical Catalog

Example 3 – XT2L 125 Ip [kA]
10 3

Limitation curves
The figure at right gives the trend of the Limitation curves of the
XT2L 125 In = 125A circuit-breaker.
The effective value of the prospective symmetrical short-circuit
current is given on the abscissas of the diagram, whereas 10 2
the peak value corresponding to the prospective short-circuit
current is indicated on the ordinates.
For a value current of 22kA, the XT2L 125 circuit breaker with a
thermal magnetic trip unit In = 125A limits the peak prospective 4
short-current current to 18kA at a voltage of 600V.
10 18 kA

1
1 10 10 2 10 3
x Irms [kA]

US Technical Catalog | SACE Tmax XT UL/CSA 4/3

 Trip curves with thermal magnetic trip unit
Trip curves for distribution

XT1 125 TMF In=15..30A XT1 125 TMF In=35...50A

t [s] t [s]
104 104

1SDC21017EF0001_A

1SDC21017EF0001_B
103 103

102 102

4 10 10

1 1

In=15A In=35A
10-1 In=20A 10-1 In=40A

In=25A In=45A

In=30A In=50A

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

XT1 125 TMF In=60...100A XT1 125 TMF In=125A

t [s] t [s]
104 104
1SDC21017EF0001_C

1SDC21017EF0001_D
103 103

102 102

10 10

1 1

10-1 I3=10xIn 10-1 I3=10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

4/4 SACE Tmax XT UL/CSA | US Technical Catalog

XT2 125 TMF In=15...30A XT2 125 TMF In=35...50A
t [s] t [s]
104 104

1SDC21018EF0001_A

1SDC21018EF0001_B
103 103

102 102

10 10
4

1 1

In=15A
In=35A
10-1 In=20A 10-1
In=25A In=40/50A
In=30A

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

XT2 125 TMF In=60...70A XT2 125 TMA In=80...100A

t [s] t [s]
104 104
1SDC21018EF0001_C

1SDC21018EF0001_D
103 103

102 102

10 10

1 1

10-1 10-1
I3=10xIn I3=5...10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

US Technical Catalog | SACE Tmax XT UL/CSA 4/5

 Trip curves with thermal magnetic trip unit
Trip curves for distribution

XT2 125 TMA In=110...125A XT3 225 TMF In=60..100A

t [s] t [s]
104 104

1SDC21018EF0001_E

1SDC21020EF0001_A
103 103

102 102

4 10 10

1 1

I3=10xIn
10-1 10-1
I3=5...10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

XT3 250 TMF In=110..150A XT3 250 TMF In=160..225A

t [s] t [s]
104 104
1SDC21018EF0001_B

1SDC21020EF0001_C
103 103

102 102

10 10

1 1

I3=10xIn I3=10xIn
10-1 10-1

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

4/6 SACE Tmax XT UL/CSA | US Technical Catalog

XT4 250 TMF In=25...50A XT4 250 TMF In=60...70A
t [s] t [s]

1SDC21021EF0001_A

1SDC21021EF0001_B
104 104

103 103

102 102

10 10
4

1 1

In=25A

In=30A

10-1 In=35A 10-1

In=40...50A I3=10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

XT4 250 TMF In=80...100A XT4 250 TMF In=110...150A

t [s] t [s]
1SDC21021EF0001_C

1SDC21021EF0001_C
104 104

103 103

102 102

10 10

1 1

10-1 10-1
I3=10xIn I3=10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

US Technical Catalog | SACE Tmax XT UL/CSA 4/7

 Trip curves with thermal magnetic trip unit
Trip curves for distribution

XT4 250 TMF In=160...225A XT4 250 TMF In=250A

t [s] t [s]

1SDC21021EF0001_E

1SDC21021EF0001_F
104 104

103 103

102 102

4
10 10

1 1

10-1 10-1
I3=10xIn I3=10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

XT4 250 TMA In=80...100A XT4 250 TMA In=110...150A

t [s] t [s]
1SDC21021EF0001_G

1SDC21021EF0001_H
104 104

103 103

102 102

10 10

1 1

10-1 10-1
I3=5...10xIn I3=5...10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

4/8 SACE Tmax XT UL/CSA | US Technical Catalog

XT4 250 TMA In=160...225A XT4 250 TMA In=250A

t [s] t [s]

1SDC21021EF0001_I

1SDC21021EF0001_L
104 104

103 103

102 102

4
10 10

1 1

10-1 10-1
I3=5...10xIn I3=5...10xIn

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

US Technical Catalog | SACE Tmax XT UL/CSA 4/9

 Trip curves with thermal magnetic trip unit
Trip curves for distribution

XT1 125 MA In=3...125A XT2 125 MA In=125A

t [s] t [s]
104 104

1SDC21022EF0001_A

1SDC21022EF0001_B
103 103

Overload limit

102 102 Overload limit

4
10 10

1 1

I3=3...11xIn
(In=15...125A)
I3=4...11xIn
(In=125A)
10-1 I3=4...11xIn 10-1
(In=3...7A)

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

XT3 225 MA In=100...200A XT4 250 MA 80...250A

t [s] t [s]
104 104
1SDC21022EF0001_C

1SDC21022EF0001_D
103 103

Overload limit Overload limit

102 102

10 10

1 1

I3=3...12xIn I3=5...10xIn
(In=100...200A) (In=80...250A)
10-1 10-1

10-2 10-2
10-1 1 10 102 10-1 1 10 102
x I1 x I1

4/10 SACE Tmax XT UL/CSA | US Technical Catalog

Trip curves with electronic trip unit
Trip curves for distribution

XT2 Ekip LS/I XT2 Ekip LS/I

L-I functions L-S functions
t [s] t [s]
104 104

1SDC21011GF0001

1SDC21012GF0001
0.4...1 0.4...1
0.4 1 0.4 1

1 10
103 103

1 1...10 10 1...10

102 102

4
10 10

102 102
1 1

10-1 10-1

10-2 10-2

10-3 10-3
10-1 1 10 10-1 1 10 10-1 1 10 10-1 1 10
x In I [kA] x In I [kA]

XT2 Ekip I XT2 Ekip LSI

I function L-S-I functions
t [s] t [s]
104 104
1SDC21013GF0001

1SDC21014GF0001
0.4...1
0.4 1
1 10

103 103

1...10
Overload limit
1 10

102 102

1 10
10 10

I2t ON
102 102
1 1

10-1 10-1
I2t OFF

10-2 10-2

10-3 10-3
10-1 1 10 10-1 1 10 10-1 1 10 10-1 1 10
x In I [kA] x In I [kA]

US Technical Catalog | SACE Tmax XT UL/CSA 4/11

 Trip curves with electronic trip unit
Trip curves for distribution

XT2 Ekip LSIG XT2 Ekip LSIG

L-S-I functions G function
t [s] t [s]
104 104

1SDC21015GF0001

1SDC21016GF0001
0.4...1
0.4 1 0.2...1

0.2 1

103 103

1...10

1 10

102 102

4 1
1...10
10

10 10

I2t ON
102
1 1
Inhibited for I>2 In

10-1 10-1
I2t OFF

10-2
10-2

10-3
10-3
10-1 1 10 10-1 1 10
x In I [kA] 10-1 1 10 102
x In

XT4 Ekip LS/I XT4 Ekip LS/I L-S

L-I functions functions
t [s] t [s]
104 104
1SDC21017GF0001

1SDC21018GF0001
0.4...1 0.4...1
0.4 1 0.4 1

1 10
1...10
103 103

1...10
1 10

102 102

10 10

102 102
1 1

10-1 10-1

10-2 10-2

10-3 10-3
10-1 1 10 10-1 1 10 10-1 1 10 10-1 1 10
x In I [kA] x In I [kA]

4/12 SACE Tmax XT UL/CSA | US Technical Catalog

XT4 Ekip I XT4 Ekip LSI
I function L-S-I functions
t [s] t [s]
104 104

1SDC21019GF0001

1SDC21020GF0001
0.4...1
0.4 1
1 10

103 103

Overload limit
1...10
1 10

102 102

1...10 4
1 10
10 10

I2t ON
102 102
1 1

10-1 10-1
I2t OFF

10-2 10-2

10-3 10-3
10-1 1 10 10-1 1 10 10-1 1 10 10-1 1 10
x In I [kA] x In I [kA]

XT4 Ekip LSIG, Ekip E-LSIG XT4 Ekip LSIG, Ekip E-LSIG
L-S-I functions G function
t [s] t [s]
104 104
1SDC21021GF0001

1SDC21022GF0001
0.4...1
0.4 1 0.2...1

0.2 1

103 103

1...10
1 10

102 102

1...10

1 10
10 10

I2t ON
102
1 1

Inhibited for I>2 In

10-1 10-1
I2t OFF

10-2 10-2

10-3 10-3
10-1 1 10 10-1 1 10 10-1 1 10 102
x In I [kA] x In

US Technical Catalog | SACE Tmax XT UL/CSA 4/13

 Trip curves with electronic trip unit
Trip curves for distribution

XT4 Ekip E-LSIG XT4 Ekip E-LSIG

OV protection UV protection

t [s] t [s]
104 104

1SDC21035GF0001
1SDC21034GF0001
1.05...1.2 0.5...0.95

1.05 1.2 0.5 0.95

103 103

102 102

4
10 10
5 5

1 1
0.1...5 0.1...5

10-1 0.1 10-1 0.1

10-2 10-2

10-3 10-3
1 1.05 1.1 1.15 1.2 1.25 1.3 0.3 0.5 0.7 0.9 1.1 1.3 1.5
x Un x Un

4/14 SACE Tmax XT UL/CSA | US Technical Catalog

Trip curves with electronic trip unit
Trip curves for motor protection

XT2-XT4 Ekip M-LIU XT2-XT4 Ekip M-LIU

L function (cold trip) (hot trip)
ratio
t [s] t-hot/t-cold
104

1SDC21070GF0001
1.2

1SDC21024GF0001
103
1

3E 5E 10E 20E

4
20EC
102 0.8

10 3EC 0.6

1 0.4

10-1 0.2

10-2 0
10-1 1 10 10 2 1 10 10 2
x In t-off [s]

XT2-XT4 Ekip M-LIU XT2-XT4 Ekip M-LIU

I function U function

t [s] t [s]
103 104
1SDC21025GF0001

1SDC21040EF0001
102 103

6 13

10 102

1 10

10-1 1

10-2 10-1

10-3 10-2
10-1 1 10 10 2 10-1 1 10 10 2
x In x In

US Technical Catalog | SACE Tmax XT UL/CSA 4/15

 Specific let-through energy curves
480V

XT2H XT2L

I2t [106 A2s] I2t [106 A2s]

10 10

1SDC21051GF0001_A

1SDC21051GF0001_B
1 1

10 -1 10 -1

10 -2 10 -2
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT2V
I2t [106 A2s]
10
1SDC21051GF0001_C

10 -1

10 -2
1 10 10 2 10 3
x Irms [kA]

4/16 SACE Tmax XT UL/CSA | US Technical Catalog

XT4H XT4L

I2t [106 A2s] I2t [106 A2s]

10 10

1SDC21051GF0001_G

1SDC21051GF0001_H
1 1

10 -1 10 -1

10 -2 10 -2
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT4V
I2t [106 A2s]
10
1SDC21051GF0001_I

10 -1

10 -2
1 10 10 2 10 3
x Irms [kA]

US Technical Catalog | SACE Tmax XT UL/CSA 4/17

 Specific let-through energy curves
600V

XT2H XT2L
I2t [106 A2s] I2t [106 A2s]
10 10

1SDC21051GF0001_D

1SDC21051GF0001_E
1 1

10 -1 10 -1

10 -2 10 -2
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT2V
I2t [106 A2s]
10
1SDC21051GF0001_F

10 -1

10 -2
1 10 10 2 10 3
x Irms [kA]

4/18 SACE Tmax XT UL/CSA | US Technical Catalog

XT4H XT4L
I2t [106 A2s] I2t [106 A2s]
10 10

1SDC21051GF0001_L

1SDC21051GF0001_M
1 1

10 -1 10 -1

10 -2 10 -2
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT4V
I2t [106 A2s]
10
1SDC21051GF0001_N

10 -1

10 -2
1 10 10 2 10 3
x Irms [kA]

US Technical Catalog | SACE Tmax XT UL/CSA 4/19

 Limiting curves
480V

XT2H XT2L
Ip [kA] Ip [kA]
10 2 10 2

1SDC21052GF0001_A

1SDC21052GF0001_B
10 10

1 1

10 -1 10 -1
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT2V
Ip [kA]
10 2
1SDC21052GF0001_C

10

10 -1
1 10 10 2 10 3
x Irms [kA]

4/20 SACE Tmax XT UL/CSA | US Technical Catalog

XT4H XT4L
Ip [kA] Ip [kA]
10 2 10 2

1SDC21052GF0001_G

1SDC21052GF0001_H
10 10

1 1

10 -1 10 -1
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT4V
Ip [kA]
10 2
1SDC21052GF0001_I

10

10 -1
1 10 10 2 10 3
x Irms [kA]

US Technical Catalog | SACE Tmax XT UL/CSA 4/21

 Limiting curves
600V

XT2H XT2L
Ip [kA] Ip [kA]
10 2 10 2

1SDC21052GF0001_D

1SDC21052GF0001_E
10 10

1 1

10 -1 10 -1
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT2V
Ip [kA]
10 2
1SDC21052GF0001_F

10

10 -1
1 10 10 2 10 3
x Irms [kA]

4/22 SACE Tmax XT UL/CSA | US Technical Catalog

XT4H XT4L
Ip [kA] Ip [kA]
10 2 10 2

1SDC21052GF0001_L

1SDC21052GF0001_M
10 10

1 1

10 -1 10 -1
1 10 10 2 10 3 1 10 10 2 10 3
x Irms [kA] x Irms [kA]

XT4V
Ip [kA]
10 2
1SDC21052GF0001_N

10

10 -1
1 10 10 2 10 3
x Irms [kA]

US Technical Catalog | SACE Tmax XT UL/CSA 4/23