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Directional overcurrent protection

of feeders and transmission lines. IBC/IBCG Directional
Overcurrent Relay

Application
■ Directional phase fault protection
(IBC)
■ Directional ground fault protection
(IBCG)

Protection and Control

■ Time overcurrent

Features
■ Mechanical targets
■ 3 inverse time/current operating
characteristics
■ Drawout case

Type IBC relay Type IBCG relay

APPLICATION
The Type IBC directional overcurrent polarizing potential by 90 degrees. available and there is a possibility that one or
relays are employed primarily for Since the directional unit has a the other source may be temporarily lost.
the protection of feeders and trans- 45-degree characteristic, its maxi- 16
mission lines in applications where mum torque will occur when the
single-phase relays are desired or fault current (balanced 3-phase fault) General
required. lags its unity-power-factor position Inverse Time Characteristic preferred where
The Types IBC and IBCG relays by 45 degrees. fault current magnitude depends largely
consist of two units, an instanta- upon system generating capacity at time of
neous power-directional unit fault.
Ground Faults—IBCG Very-inverse and Extremely-inverse Time
(bottom) of the induction-cup type,
and a time overcurrent unit (top) of The IBCG relay is designed for Characteristics are preferred where fault
the induction-disk type. The direc- protection against ground faults and current magnitude is dependent mainly upon
tional-unit contacts control the is consequently of lower operating location of fault relative to relay and only
operation of the overcurrent unit current range. The relays used for slightly upon system generation setup.
(directional control). ground-fault protection usually have
a low-range operating coil which is Target Seal-in-units are provided for the time
rated either 0.5/4 or 1.5/12 A. 2/16 and instantaneous overcurrent units and are
rated 0.2/2 A.
Phase Faults—IBC rating is also available.
The Type IBC relays are frequently The directional unit of the Type
applied for phase-fault protection of IBCG is dual-polarized and may be
a single line. Typical external polarized by current alone, voltage COIL
connections of current and potential alone, or by both simultaneously.
transformers are shown in Fig. 1. This dual polarization is desirable on The short-time and continuous ratings of the
With this connection, the current (at applications where both current and operating coil circuits are shown in Table 1.
unity-power-factor load) leads the potential polarizing sources are

GE Power Management
301
 IBC/IBG Directional Overcurrent Relay
COIL CONNECTION DIAGRAM
The current and potential polarizing Table 2. Non-directional instantaneous unit ratings Fig. 1. Typical 90-degree connection of three Type
IBC relays used for directional overcurrent
coils of the dual-polarized ground relay protection of a single line.
are rated as follows: Contin. 1 Sec
Range Connection and Rating Rating
Potential polarizing coils—120 V (A) Range (A) (A) (A)
continuous at rated frequency.
Low (Series) 6-30 a 10.2
Current polarizing coils—continuous 6-150 260
High (Parallel) 30-150 a 19.6
rating of 5 A with a one (1) sec rating of
160 A. a This range is approximate, which means
Table 1. Time overcurrent unit taps and ratings that 6-30 and 30-150 might actually be 6-28
and 28-150. However, there is at least a one-
amp overlap between the maximum “Low”
Tap 1 Sec Cont. Rating (A) setting and the minimum “High” setting.
Range Character Rating
(A) (A) Min. Tap Max. Tap

Inverse 70 1.6 5.0 AVAILABLE SETTINGS

0.5-4.0 V. Inverse 140 4.0 13
Time Overcurrent Units:
Ext. Inv. 125 3.5 10
■ 0.5-4.0 — 0.5, 0.6, 0.7, 0.8, 1, 1.2, 1.5,
V. Inverse 260 10 30.5 2, 2.5, 3, 4
1.5-12
■ 1.5-12 — 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8,
Ext. Inv. 260 9.5 20
10, 12
CONTACTS
2-16 Inverse 260 8 20
■ 2-16— 2, 2.5, 3, 4, 5, 6, 7, 8, 10, 12, 16 The current-closing rating of the induc-
tion unit contacts is 30 A for voltages
not exceeding 250 V. Their current-
carrying rating is limited by the tap
rating of the seal-in unit.

SELECTION GUIDE
0.2/2.0 A TARGET AND SEAL-IN UNIT
Approx. Wt.
Rating (A) Model Number in lbs (kg)
Freq. Case
(Hz) Time Non-Dir. Dir. Inverse Very Inverse Ext. Inverse Inverse Very Inverse Ext. Inverse Size
Inst. Net Ship
Unit P.U.a Time Time Time Time Time Time
Unit
16 IBC, PHASE-TYPE, 120 V 1 N.O. CONTACT 2 N.O. CONTACTS
1.5-12 — ----- 12IBC53M1A 12IBC77M1A ----- 12IBC54M1A 12IBC78M2A 22 35
2-16 — 12IBC51M1A ----- ----- 12IBC52M1A ----- ----- (10) (15.9)
60
1.5-12 — ----- 12IBC53M1Y1A 12IBC77M1Y1A ----- ----- ----- 23 36
6-150
2-16 — 12IBC51M1Y1A ----- ----- ----- ----- ----- (10.4) (16.3)
M-1
1.5-12 — ----- 12IBC53M2A 12IBC77M2A ----- 12IBC54M2A 12IBC78M3A 22 35
2-16 — 12IBC51M2A ----- ----- 12IBC52M2A ----- ----- (10) (15.9)
50
1.5-12 — ----- 12IBC53M2Y1A 12IBC77M2Y1A ----- ----- ----- 23 36
6-150
2-16 — 12IBC51M2Y1A ----- ----- ----- ----- ----- (10.4) (16.3)
IBC, GROUND-TYPE, 120 V 1 N.O. CONTACT 2 N.O. CONTACTS
0.5-4 — 12IBCG51M1A 12IBCG53M1A 12IBCG77M1A 12IBCG52M1A 12IBCG54M1A 12IBCG78M1A
22 35
1.5-12 — ----- 12IBCG53M2A 12IBCG77M2A ----- 12IBCG54M2A 12IBCG78M2A
(10) (15.9)
2-16 — 12IBCG51M2A ----- ----- 12IBCG52M2A ----- -----
60
0.5-4 — 12IBCG51M1Y1A 12IBCG53M1Y1A ----- ----- ----- -----
23 36
1.5-12 6-150 — ----- 12IBCG53M2Y1A ----- ----- ----- -----
(10.4) (16.3)
2-16 — 12IBCG51M2Y1A ----- ----- ----- ----- -----
M-1
0.5-4 — 12IBCG51M3A 12IBCG53M3A 12IBCG77M3A 12IBCG52M3A 12IBCG54M3A -----
22 35
1.5-12 — ----- 12IBCG53M4A 12IBCG77M4A ----- 12IBCG54M4A -----
(10) (15.9)
2-16 — 12IBCG51M4A ----- ----- 12IBCG52M4A ----- -----
50
0.5-4 — 12IBCG51M3Y1A 12IBCG53M3Y1A ----- ----- ----- -----
23 36
1.5-12 6-150 — ----- 12IBCG53M4Y1A ----- ----- ----- -----
(10.4) (16.3)
2-16 — 12IBCG51M4Y1A ----- ----- ----- ----- -----
a At rated voltage.

302 Directional Relays