GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual page 256

8.5 PROTECTION SCHEMES
a) WINDING 1 ELEMENTS
To ensure that only the Phase Time overcurrent elements operate the trip relays (and any other output relays) selected by
the logic, disable all protection features except Phase Time Overcurrent. Use the general test setup shown below:
Connect the current supply to terminals X = H1 and Y = G1 to test the Winding 1 Phase A element. Monitor the appropriate
output relays per the FlexLogic™ settings.
b) PICKUP LEVEL
1. With the interval timer disabled, apply the current signal and increase its magnitude slowly until the trip relay and all the
selected auxiliary relays operate. If the element has a very inverse time characteristic, it is easier and more accurate to
increase the current far above the pickup level until the trip relay operates then reduce the current to just above the
operate level. Then, current can be slowly reduced below the operate level and observed for a reset action on the trip
relay. This reset level for the current should be approximately 98% of the pickup level. Once the relay drops out, slowly
increase the current until the trip contact closes. The operate level should correspond to the pickup setting.
2. Check that one of the following messages is displayed:
LATCHED a
W1 Phase Time OC
3. The message will indicate
c) OPERATING TIME
Using a table like the one shown below, select three (3) or four (4) values of current multiples at which the timing is to be
measured. Enter the expected operating times from the timing curve applied in the settings. Using the setup shown in Fig-
ure 8–9: General Test Setup on page 8–18 and the Interval Timer enabled, set the current level to the desired value and
apply suddenly by closing the double-pole switch. Record the operating time and compare it to the expected value. Repeat
8
for all desired values of current.
CURRENT NOMINAL TIME
MULTIPLE
1.5
3
5
d) RESET TIME
A precise measurement of the reset time requires a relay test set capable of dynamic operation, with three sequenced
stages, each with programmable current levels and time duration external contact, and flexible triggering. To perform such
a test, please contact GE Multilin for detailed test instructions.
8-18
Courtesy of NationalSwitchgear.com
Figure 8–9: GENERAL TEST SETUP
OPERATED a
W1 Phase Time OC
or , depending on the setting for the target.
LATCHED OPERATED
MEASURED
TIME
745 Transformer Management Relay
8 COMMISSIONING
GE Multilin