GE 239, Instruction Manual

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8-8 239 Motor Protection Relay GE Multilin
8 TESTING 8 TESTING
8
8.13 ROUTINE MAINTENANCE VERIFICATION
1. Once a relay has been properly installed, periodic tests can be performed to check correct oper-
ation of the protection system. Many conditions can be simulated without creating the actual trip/
alarm conditions themselves. This is done by changing relay setpoints to values which will initiate
trips and alarms during normal motor operation. Changed setpoints should be returned to their
proper values when tests have been completed. The Setpoint Access terminals must be shorted
together to allow setpoint changes.
2. To test relay functions using phase current data, with the motor running, change
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setpoint to a value under the actual motor current.
The trip relay will activate after thermal capacity builds up to 100%. The time to trip at a given
overload level should never be greater than the time on the overload curve. However, the trip
time could be less depending upon how much thermal capacity was already accumulated. Larger
overloads, representing short circuits or mechanical jams, can be simulated by changing the
6
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setpoint to a value much lower than the
actual motor phase current.
3. Unbalance trip or alarm conditions can be simulated by changing the Unbalance Trip or Alarm
Level setpoints to values below the actual unbalance present at the motor terminals. The unbal-
ance feature will not work if the motor load is
≤
30% FLC.
4. Other trip or alarm conditions using ground current data and RTD temperature data can be simu-
lated using the procedures outlined in the previous sections.
5. To test the operation of the 239 output relays and the switchgear connected to them setpoint
6
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is used. The motor must be stopped in order for this
function to operate. While this setpoint is displayed, use the or key to scroll
through each message. The currently selected relay will be energized and all other relays will be
de-energized. As soon as another setpoint or actual value is displayed the 239 returns to normal
operation.
6. To test the analog output hardware repeat the test in Section 8.9: ANALOG OUTPUT on page 8–
6. This test can be performed while current is present.
VALUE
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VALUE
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