7.12 Routine Maintenance Verification - GE 239 Instruction Manual

7.12 Routine Maintenance Verification

7–108
Courtesy of NationalSwitchgear.com
1. Once a relay has been properly installed, periodic tests can be performed to check
correct operation 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
SYSTEM SETUP\MOTOR DATA\MOTOR FULL LOAD CURRENT
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
SETUP\MOTOR DATA\MOTOR FULL LOAD CURRENT
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 unbalance 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 simulated 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
S5: TESTING\TEST RELAYS & LEDS\OPERATION TEST
be stopped in order for this function to operate. While this setpoint is displayed, use
the or
VALUE VALUE
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 7.8: Analog Output on
page –104. This test can be performed while current is present.
setpoint to a value much lower
key to scroll through each message. The currently
239 MOTOR PROTECTION RELAY – INSTRUCTION MANUAL
CHAPTER 7: TESTING
S2:
setpoint to a value under
S2: SYSTEM
is used. The motor must