GE Multilin 239 Motor Protection Relay 4-23
4 PROGRAMMING 4 PROGRAMMING
4
b) PHASE S/C
• PHASE S/C TRIP:
In any application where the available short circuit current is above the inter-
rupting capability of the contactor, short circuit currents must cause a fuse or circuit breaker to
operate. This prevents damage to the contactor which is not designed to interrupt normal levels
of short circuit current. In an application with fuses, program the setpoint
6 3527(&7,21?3+$6(
&855(17?3+$6( 6&?3+$6( 6?& 75,32))
to prevent the contactor from attempting to trip during a
short circuit.
If a circuit breaker which can be tripped by an external contact closure is available upstream from
the contactor, it is possible to program the setpoint
6 3527(&7,21?3+$6( &855(17?3+$6( 6
&?3+$6(6?&75,3$8;,/,$5<
to cause a short circuit to activate the auxiliary relay instead of the trip
relay. Though, it is also possible to activate both the trip & auxiliary relays simultaneously. The
auxiliary relay could then be connected to the upstream breaker to cause it to open for a short cir-
cuit. Ensure that the auxiliary relay is only programmed to activate under short circuit when used
in this manner.
SPECIAL NOTE:
The AUXILIARY and TRIP status indicators will both operate for these trips
even if the TRIP relay is not selected for use (i.e. AUXILIARY). If the breaker cannot be externally
tripped, program the setpoint
63527(&7,21?3+$6(&855(17 ?3+$6(6&?3+$6(6?&75,32)) to pre-
vent the contactor from attempting to trip during a short circuit. If a breaker is used as the motor
starter interrupting device, short circuit protection would generally be enabled as it will normally
be capable of handling the fault current. Short circuit protection causes the breaker to open
quickly to prevent excessive mechanical damage or fire due to any large phase current. Com-
plete protection from phase-to-phase and phase-to-ground faults is provided with this feature.
Table 4–2: 239 PHASE OVERLOAD TRIP TIMES (SECONDS)
CURVE
NUMBER
MULTIPLE OF MOTOR FULL LOAD CURRENT
1.03 1.05 1.1 1.5 2 2.5 3 4 5 6 8 10 11
1 1437 854 416.7 70.0 29.2 16.7 10.9 5.8 3.64 2.50 1.39 0.88 0.73
2 2874 1707 833.4 140.0 58.3 33.3 21.9 11.7 7.29 5.00 2.78 1.77 1.46
3 4311 2561 1250.0 210.0 87.5 50.0 32.8 17.5 10.93 7.49 4.16 2.65 2.19
4 5748 3415 1666.7 280.0 116.6 66.6 43.7 23.3 14.57 9.99 5.55 3.53 2.91
5 7184 4269 2083.4 349.9 145.8 83.3 54.7 29.1 18.22 12.49 6.94 4.42 3.64
6 8621 5122 2500.1 419.9 174.9 100.0 65.6 35.0 21.86 14.99 8.33 5.30 4.37
7 10058 5976 2916.8 489.9 204.1 116.6 76.5 40.8 25.50 17.49 9.71 6.18 5.10
8 11495 6830 3333.5 559.9 233.3 133.3 87.5 46.6 29.15 19.98 11.10 7.06 5.83
9 12932 7683 3750.1 629.9 262.4 149.9 98.4 52.5 32.79 22.48 12.49 7.95 6.56
10 14369 8537 4166.8 699.9 291.6 166.6 109.3 58.3 36.43 24.98 13.88 8.83 7.29
11 15806 9391 4583.5 769.9 320.7 183.3 120.3 64.1 40.08 27.48 15.27 9.71 8.01
12 17243 10245 5000.2 839.9 349.9 199.9 131.2 70.0 43.72 29.98 16.65 10.60 8.74
13 18680 11098 5416.9 909.9 379.1 216.6 142.1 75.8 47.36 32.48 18.04 11.48 9.47
14 20116 11952 5833.5 979.9 408.2 233.2 153.0 81.6 51.01 34.97 19.43 12.36 10.20
15 21553 12806 6250.2 1049.8 437.4 249.9 164.0 87.4 54.65 37.47 20.82 13.25 10.93
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