P R OT E C T I O N

MCTI 19, 39, 40

Breaker Fail Overcurrent Measurement

Relay types MCTI 39 and MCTI 40 are three phase

or two phase and earth fault instantaneous
overcurrent relays and the MCTI 19 is a single
phase relay. The relays have been designed to
be applied as current detectors in breaker fail
protection schemes. The MCTI 40 is particularly
suitable for breaker fail applications where
single/three pole breaker tripping is possible,
since control of the current detector is provided
on a per phase basis. Simple application
diagrams are shown in Figure 2.
In the substation single line diagram shown here
on the left:
if breaker A fails to remove the fault at F, breakers
B, C, D and E should be tripped simultaneously by
Figure 1 breaker fail protection for breaker A, to isolate the
Type MCTI 39 Relay busbar. The breaker fail timer relay should be set
withdrawn from case in excess of the time required for the breaker to
clear the fault current under normal
B circumstances.
D
A particular feature of the relay is a fast reset.
F A This is important since it will be possible to set
E the time delay closer to the breaker trip time.
L BB
C

MODELS AVAILABLE

> Type MCTI 19

Single phase relay with 4 change-over contacts.

Customer Benefits
• Fast reset time-typically > TYPE MCTI 39
15ms Three phase device with a common output element for all three phases,
• Low burden giving 4 change-over contacts.
• Low overshoot
• Suitable for breaker fail
> TYPE MCTI 40
schemes
A three phase device with an independent output element for each phase,
giving 2 normally open contacts per phase.

AREVA T&D
 PR 13 14 PR 13 14
MVTT 14 MCTI 39

1 3 13 14 1 3 13 14
MCTI 39 MVTT 14

2 4 1 3 2 4 1 3

Common Circuit Breaker Common Circuit Breaker

Alternative (a) Trip Relay Type MVAJ Alternative (b) Trip Relay Type MVAJ

Figure 2 DC connections for local breaker back-up relay MCTI 39 for use with time delay relay Type MVTT 14

DESCRIPTION TECHNICAL DATA

> For breaker fail applications > Ratings

The MCTI is enabled/disabled by application/removal of • AC Current (In) 1A or 5A

the dc auxiliary supply to the relay (on a per phase
basis for the MCTI 40). The relay will quickly reset • DC Auxiliary Vx dc Operative range
when the protected circuit breaker interrupts primary voltages 30/34V 24 - 40V
current. 48/54V 37.5 - 66V
110/125V 87.5 - 150V
The MCTI 19, 39, 40 relays are not suitable for use in 220/250V 175 - 300V
applications where the output relays are to be
energised continuously. • Rated frequency 50 or 60Hz

The 220/250V dc auxiliary version of the MCTI 40 is

only suitable for use in applications where the dc
auxiliary supply is not continuously applied.

> Burdens

Setting Rated Tap At setting current At rated

range current Setting Multiplier Setting current
amps 1x 2x (maximum)
5% to 40% 1A Min 0.05VA 0.12VA 2.64VA
Max 0.08VA 0.22VA 0.15VA
5A Min 0.05VA 0.11VA 4.37VA
Max 0.12VA 0.43VA 0.73VA
10% to 80% 1A Min 0.05VA 0.12VA 1.50VA
Max 0.09VA 0.28VA 0.14VA
5A Min 0.05VA 0.12VA 1.97VA
Max 0.26VA 0.96VA 0.43VA
20% to160% 1A Min 0.05VA 0.12VA 0.68VA
Max 0.13VA 0.44VA 0.05VA
5A Min 0.07VA 0.22VA 1.07VA
Max 1.10VA 4.29VA 0.39VA

NOTE: For breaker fail schemes, the quiescent current drain is zero.

DC Auxiliary Nominal Quiescent Operated

supply voltage current drain current drain
30/34V 25mA 100mA
48/54V 20mA 85mA
110/125V 12mA 60mA
220/250V 12mA 45mA
For MCTI 19 or MCTI 39 relays or per phase for MCTI 40 relay.

Fast breaker failure protection in

2>3
conjunction with MVTT
> Setting ranges INFORMATION REQUIRED
WITH ORDER
Tap setting (Is) 20%, 40% 80%, 160% In.
10%, 20%, 40%, 80% In. Relay type
5%, 10%, 20%, 40% In. CT Secondary rating
Setting range
Current setting Auxiliary supply voltage
multiplier 1-2x tap setting
This gives effective
setting ranges of: 71 26
4 holes Ø4.4 23.5
20 - 320% In. Figure 3
10 - 160% In. Case outline: size 3
5 - 80% In. 168 159

Push button
projection 10 max
Panel cut-out:
> Operating time 73 Flush mounting fixing details

32 212 25 min.
Operate time <10ms
Reset time <15ms, typically 12ms 177

157 max.

Reset
> Contacts 77

All dimensions in mm Flush mounting

MCTI 19, 39 4 Changeover self reset

MCTI 40 2 normally open or 1 normally
open and 1 normally closed per
52
phase or earth fault element 97 4 holes Ø 4.4
Figure 4 23.5

Case outline: size 4

All dimensions in mm.
> Contact ratings 168 159

Push button
Current Make and carry Make and carry Break projection 10 max. 99
Panel cut-out:
continuously for 0.2s Flush mounting fixing details.

AC 1250VA with 7500VA with 1250VA with 32 212

25 min.
maxima of 5A maxima of 30A maxima of 5A
and 300V and 300V and 300V
DC 1250W with 7500W with 50W (Resistive) 177 157 max.
maxima of 5A maxima of 30A 25W (Inductive)
and 300V and 300V with L/R=40ms
with maxima
103
of 5A and 300V Flush mounting. 11

> Cases
103. 6
149 4 holes ø4.4
23. 5
Relay type Case size Figure 5
MCTI 19 3 Case outline: size 6 All dimensions in mm.
168 159
MCTI 39 4
MCTI 40 6
Outline drawings are shown in Figures 3, 4 and 5. Push button
151
projection 10 max.
Panel cut-out:
Flush mounting fixing details.

32 212
25 min.

177 157 max.

155
Flush mounting. 11
 AREVA TRACK RECORD –
BREAKER FAILURE SCHEMES
>> Over 18,500 MCTI relays shipped since 1984,
for breaker failure applications.
>> Cost – effective breaker failure protection available in
MiCOM feeder protection and busbar protection P740.
>> Integrated MiCOM P821 preferred in modern
stand – alone applications.

MiCOM is a registered trademark of AREVA. All trade names or trademarks mentioned herein whether registered or not, are the property of their owners. - 389191982 RCS PARIS - Printed in France - SONOVISION-ITEP
AUTOMATION-L3-MCTI-BR-09.05-1203-GB - ©2005 AREVA - AREVA, the AREVA logo and any alternative version thereof are trademarks and service marks of AREVA.

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