GE 745 Instruction Manual page 285

CHAPTER 7: COMMISSIONING
Note
NOTE
7.5.17.3 Underfrequency 2
7.5.17.4 Overfrequency
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
 Provided that the operate times are not scattered over a wide range, it
may be desirable to repeat this test several times and average the results.
 If there is a wide scatter, verify the test setup and ensure the signal
source behaves in a consistent manner.
The blocking from logic input, if enabled, can be tested as described in earlier tests for
other elements.
 Disable all protection functions except the underfrequency 2 function.
 Verify that settings match in-service requirements. Enter/modify
settings and logic in the
UNDERFREQUENCY 2
 Repeat the appropriate steps of Underfrequency 1 on page 7–44 for this
element.
 Compare the results to the settings for the underfrequency 2 element.
 Disable all protection functions except overfrequency.
 Verify that settings match in-service requirements.
Overfrequency settings are modified in the
FREQUENCY
Voltage input function (voltage input enabled):
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 frequency to 60.00 Hz (or 50.00 Hz) and the voltage amplitude
to the rated VT secondary voltage.
 Set the current amplitude to rated CT secondary.
 Monitor the appropriate trip and auxiliary relays.
 Reset all alarms and indications on the relay.
The 745 display should remain unchanged with no trip indications.
 Slowly increase the frequency until the output relay(s) operate.
 Check that the frequency at which operation took place is the selected
frequency setting.
 As the frequency is varied, verify that the
FREQUENCY
value of system frequency.
 Slowly reduce the voltage.
 Note the voltage at which the output relay(s) reset.
S4 ELEMENTS

setpoints menu.
OVERFREQUENCY settings menu.

SYSTEM FREQUENCY
actual value indicates the correct

PROTECTION SCHEMES
FREQUENCY

S4 ELEMENTS

A2 METERING

7–47