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Directional Overcurrent Ground Relays
Types IRP, IRC and IRD
Continuous
Relay
Range
Rating
Type
AMPS
(Amperes)
0.5-2.5
2-6
IRC
4-12
0.5-2.5
2-6
IRP
4-12
0.5-2.5
2-6
IRD
4-12
φ
Degrees current lags voltages at tap value current.
†
Thermal capacities for short times other than one second may be calculated on the basis of time
being inversely proportional to the square of the current.
RELAY TYPE
IRC
IRP
IRD Current Unit
IRD Current Unit
φ
Degrees current leads or lags voltage at 120 volts on voltage polarized units and 5 amperes on current polarized units.
∆
Burden of voltage polarized units taken at 120 volts. Burden of current polarized units taken at 5 amperes.
†
One second rating.
††
30 second rating. The 10 second rating is 345 volts. The continuous rating is 120 volts.
ENERGY REQUIREMENTS – 60 HERTZ
DIRECTIONAL UNIT OPERATING CIRCUIT BURDEN
One Second
†
Rating
(Amperes)
--
230
--
230
12
280
10
230
10
230
12
280
10
230
10
230
12
280
ENERGY REQUIREMENTS – 60 HERTZ
DIRECTIONAL UNIT POLARIZING CIRCUIT BURDEN
RATING
†
230 Amperes
††
208 Volts
†
230 Amperes
††
208 Volts
VOLT AMPERES
At
At 3 Times
Power
Minimum
Minimum
Factor
Tap Value
Tap Value
φ
Angle
Current
Current
44.0
0.033
42.5
0.58
31.8
0.64
34.5
0.03
34.5
0.44
25.0
0.48
45.0
0.07
45.0
1.04
32.4
1.16
∆
VOLT AMPERES
1.45
11.2
1.45
11.2
At 10 Times
At 20 Times
Minimum
Tap Value
Current
0.30
3.3
5.28
58.0
6.12
70.0
0.23
2.8
4.08
48.0
4.62
53.6
0.59
6.6
9.9
106.0
10.8
121.2
POWER FACTOR ANGLE
8° Lag
28° Lag
8° Lag
28° Lag
41-133S
Minimum
Tap Value
Current
14.2
240.0
272.0
11.5
182.0
216.0
26.0
420.0
472.0
φ
13
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