Protection Schemes
745
Transformer Management Relay
Commission
ing
http://www.GEindustrial.com/multilin
7–31
GE Multilin
e) Winding 2 and 3 Elements
Because the Winding 2 and 3 elements can be set with completely different
parameters than the element for Winding 1, it is necessary to repeat the full set of
tests described for the Winding 1 element in this section.
Connect the current supply to terminals X = H4 and Y = G4 to test the Winding 2
element. Use X = H7 and Y = G7 for the Winding 3 element.
The blocking from logic input, if enabled, can be tested as described in
earlier tests for other elements.
Frequency
a) Setup
The power system frequency is measured from the voltage input if it has been
enabled. If there is no voltage input, it is measured from the Winding 1 Phase A
current signal. These tests require a variable-frequency current source for relays
without a voltage input and a variable-frequency voltage and current source for
relays with a voltage input. Connections are shown in the figure below. Only
perform tests specific to the relay model.
The underfrequency, overfrequency, and frequency decay elements are all
supervised by optional adjustable minimum current and minimum voltage level
detectors. When testing the performance of these elements on a 745 with the
voltage input enabled, it may be necessary to inject a current signal into Winding 1
Phase A if the current supervision is enabled, or else the detectors will not operate.
FIGURE 7–12: Frequency Element Testing
b) Underfrequency 1
As a preliminary step, disable all protection functions except Underfrequency 1.
Verify that settings match the in-service requirements. Settings are entered or
modified in the
S4 ELEMENTS
!"
FREQUENCY
!
UNDERFREQUENCY 1
settings menu.
Voltage Input Function (Voltage Input Enabled):
1. Using the variable-frequency voltage/current source connected to terminals C11
and C12 for the voltage signal and H1 and G1 for the current signal, set the fre-
quency to 60.00 Hz (or 50.00 Hz for 50 Hz systems) and the voltage amplitude
to the rated VT secondary voltage.
2. Set the current amplitude to rated CT secondary. Monitor the appropriate trip
and auxiliary relays. Reset all alarms and indications on the relay. The relay
display should remain with no trip indications.
3. Slowly decrease the frequency until the output relay(s) operate. Check that the
operation took place at the selected frequency setting.
4. As the frequency is varies, verify that the correct system frequency is displayed
by the
A2 METERING
!"
FREQUENCY
!
SYSTEM FREQUENCY
actual value.
5. Slowly reduce the voltage and note the voltage at which the output relay(s)
reset. Check that this dropout voltage is approximately the voltage supervision
value in the
S4 ELEMENTS
!"
FREQUENCY
!
UNDERFREQUENCY 1
!"
MINIMUM
OPERATING VOLTAGE
setpoint.
NOTE
NOTE
Summary of Contents for Multilin 745
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