PROTECTION

CTUM15 & CTIGM15

Sensitive Earth Fault Relays

CTUM15 relay is a sensitive current relay used for detection high

resistance earth faults. It can also be used for CBCT applications for
detecting low earth leakage currents. CTIGM15 is another variation
of CTUM15 intended for CBCT applications.

Features Description
• Wide/sensitive current setting range. Figure 1 shows the typical block diagram of
• Wide range of time settings relay type CTUM 15. The incoming current is
• Extremely low burden stopped down by an internal current transformer
• Settings adjustable on relay front panel and converted to a voltage by a variable resisitor
• Suitable for a wide range of ac and dc network. The signal is compared with an internal
auxiliary supplies reference. When this reference level is exceeded
• Immunity against transients a time delay has elapsed, a relay operates two
• Compact case sets of contacts and a hand reset mechanical
flag.
Application In case of relay type CTIGM 15, the adjustable
time delay circuit (ts) is eliminated and the relay
It may not be always possible to detect high has an operating time of about 100 ms (at two
resistance faults by conventional earthfault times the setting).
relaying. In such cases a very sensitive current
relay will be required. CTUM 15 can be used
for this purpose. It can be connected residually Technical data
since it has an adjustable definite time delay
Current Rating
provided to take care of transient spills in
the residual circuit due to CT Type CTUM 1A or 5A for CTUM 15
15 & CTIGM 15 Sensitive Earth Fault Relays 1A for CTIGM 15
mismatch. Also, its low burden enables it to be
used with existing CTs/relays without affecting Current Setting Range (Is)
the latter’s performance.
• For CTUM 15 relay 10 mA to 160mA in
Another application of type CTUM 15 is the steps of 10 mA (for 1A relay) 50 mA to
detection of low earth leakage currents in fire 800 mA in steps of 50 mA (for 5A relay)
sensitive locations (like mines). Here, when used
with suitably designed core balance current • For CTIGM 15 relay 5 mA to 515 mA in
transformers (CBCT), the overall sensitivity steps of 2 mA.
achieved could be as low as 2A (primary) or
lower. In such applications, sometimes a longer Time setting range (ts)
time delay may not be warranted and therefore
the relay type CTUM 15 may be set for • CTUM 15 relay:
instantaneous operation. 0.56 s to 7.56 s in steps of 0.5 s and
Customer Benefits also an instantaneous setting of 60 ms.
There will still be a built-in delay of about 60 ms.
• Sensitive Earth fault • CTIGM 15 relay:
detection to overcome effects of transients, if any. Type
CTIGM 15 is another variation of CTUM 15, 100 ms at two times the setting current
• Adjustable definite (factory set).
time delay without the adjustable time delay. It is exclusively
intended for CBCT application and provides a
cost effective alternative to CTUM 15. Rated auxiliary voltage(Vx)

The relay will be suitable for use with any of the

following supply voltages:

24,30/34,48/54,110/125, 220/250V dc.

110/125,220/250V ac, 50/60 Hz.

AREVA T&D
 Thermal withstand

• Continuous
2.4 x In

• Short time
57 x In for 3s for 1A relay.
230A for 3s for 5A relay.
100 x In for 1s for 1A relay.
400A for 1s for 5A relay.

Rated frequency

50/60 Hz.

Limits of operative frequency range

CTUM 15 relay withdrawn from the case
47 Hz to 62 Hz.

Limits of operative range

Vx Operating range
(v) (v)

24 dc 19.2 to 28.8
30/34 dc 24.0 to 37.5
48/54 dc 37.5 to 60.0

110/125 ac/dc 87.5 to 150.0

220/250 ac/dc 175.0 to 275.0

The same relay can be used with different Vx ratings

(Refer Figure 1 and Table 1).

Reset Current
Relay resets at greater than 95% of operating current.

Reset Time

Typically 150 - 250 msecs. (This is the time measured

between switching off of a fault current and the resetting
of output contacts.)

Operation indicator

The output unit is fitted with a hand reset mechanical

flag.

AC burden (CTUM 15)

Less than 0.0001VA at min. setting

current (10 mA/50 mA).

Less than 0.002VA at max. setting

current (160 mA/800 mA).

2>3
Auxiliary Burden

Vx Quiescent Operated
V Condition Condition
mA mA

24 DC 12 43

30/34 DC 20 47

48/54 DC 32,41 43,50

110/125 DC/AC 45,49 48,52

220/250 DC/AC 46,47 47,49

Note:
1. Quantities in brackets correspond to ac
auxiliary supply.

2. Burden of CTIGM 15 relay will be

furnished on request.

Operating Temperature range

-25°C to + 55°C

Storage

The relay meets the requirements of BS.2011 (IEC.68) to class 25/070/36, that is,
storage and transport temperature range -25°C to +70°C and 56 days withstand of
40°C and 95% relative humidity.

Contacts

Two pairs of self reset contacts.

2 N/O or 2 N/C or 1 N/O & 1 N/C.

Accuracy

Reference conditions

Ambient temperature: 27°C ± 2°C

Frequency: Rated value ± 0.5% (50/60 Hz)
Aux. voltage: Rated value
Current setting (Is) :
160 mA/800 mA
Time setting (ts): 7.56 sec.
 Contact Ratings

Make and carry Make and carry Break

continuously for 0.5 second

AC 1250VA with 7500VA with 1250VA with

maxima of 5A maxima of 30A maxima of 5A
and 660V and 660V and 660V

DC 1250W with 7500W with 100W (resistive)

maxima of 5A maxima of 30A 50W (inductive)
and 660V and 660V maxima of 5A
and 660V

Figure 1:
Block diagram of relay type CTUM 15 (½N
case)

4>5
Notes

1. For 220/250V ac/dc auxiliary supply applications, an external series resistance of

2.7K, 35W should be connected to terminal 11.
2. The indicated terminal details are applicable for CTUM 15/CTIGM 15 relays housed
in ½N case.
3. For the terminal details of ID case version, please refer Table-1(version 2&3).

Table - 1

Version Auxiliary supply Terminal Case size

1 24V dc 5 ½N
30/34V dc 6
48/50V dc 7
110/125V ac/dc 8
220/250V ac/dc 11
Neutral/Negative 12

2 24V dc 5 1D
30/34V dc 6
48/54V dc 7
Negative 8

3 110/125V ac/dc 6 1D
220/250V ac/dc 7
Negative/Neutral 8

Note: For 220V/250V ac/dc auxiliary supply, an external resistance of 2.7K,

35W should be connected to terminal II (Refer Figure 1).

Accuracy under reference conditions

Pick-up error over the entire

range: ±5%
Time error over the entire range:
±5% or 35 ms whichever is greater.

Additional allowable errors due to influencing quantities

• Temperature : ± 25°C to + 55°C

Pick-up error : ± 3%
Time error : ± 3%

• Frequency : 47 HZ to 62 Hz.
Pick-up error : ± 1%
Time error : No additional error

• Auxiliary Voltage
Pick-up error : ± 2%
Time error : No additional error
 Mechanical durability

The relay will perform a minimum of 10000 operations.

Vibration

The relay meets the requirements of BS 142 Section 22,

Clause 8.2 to Class S2.

Insulation

The relay meets the requirements of IEC 255-5/IS 3231,

2 KV for 1 minute.

Impulse voltage

The relay complies with the requirements of IEC 255-4/IS

8686.

High Frequency Interference

The relay complies with IEC

MiCOM is a registered trademark of AREVA.All trade names or trademarks mentioned herein whether registered or not, are the property of their owners.
255-6
Appendix C to Class III/IS 8686.

Case

Size 1D, 10 terminal or size ½ N, 12 terminal. Both flush

mounting.

Information required with order

1. Aux. supply

AREVA, the AREVA logo and any alternative version thereof are trademarks and service marks of AREVA
2. Contact combination required

3. Current rating (for CTUM 15 relay only)

4. Case

AREVA T&D
Pallavaram Works
19/1, G.S.T. Road,
Pallavaram, Chennai - 600 043
Tel: 91-44-2264 8000

Fax: 91-44-2264 0040

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design of our products may change at any time. Whilst every effort
is made to produce up to date literature. This brochure should only
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