Volts-Per-Hz 1(2) - GE 745 TRANSFORMER MANAGEMENT RELAY Instruction Manual

10 COMMISSIONING
The volts-per-hertz operating levels are set in terms of the relay-input voltage divided by the frequency of that
voltage.
1. Disable all elements except Volts-per-hertz 1(2). Monitor the appropriate contact. Use the test setup in Fig-
ure 10–11: FREQUENCY ELEMENT TESTING on page 10–34 with variable-frequency voltage source.
2. The Volts-per-hertz settings are found under:
SETPOINTS S4 ELEMENTS / OVEREXCITATION / VOLTS-PER-HERTZ 1(2) /...
3. Apply a voltage starting at 60 Hz and increase the magnitude until the element operates. Reduce the fre-
quency in steps of 5 Hz and repeat the measurement. The element should operate at a consistent value of
V/Hz equal to the setting of the element.
4. Check that the TRIP and PICKUP LEDs are on and the following trip message is displayed:
SS LATCHED (OPERATED):
SS Volts-Per-Hertz 1(2)
5. For timing tests, prepare a table of expected operating time versus applied V/Hz signal from the selected
timing curve for the element. Using the variable frequency function generator to simulate the different V/Hz
ratios, apply suddenly to the relay and measure the operating time.
The 5th Harmonic Scheme operates if the 5th harmonic content of any current signal connected to the relay
exceeds the threshold setting, for the set time, provided that the level is above the set threshold.
1. Disable all protection functions except the 5th Harmonic function.
2. The 5th Harmonic scheme settings are under:
SETPOINTS S4 ELEMENTS/OVEREXCITATION/5th HARMONIC LEVEL
3. This test requires a current generator capable of producing a fundamental and 5th harmonic component.
Connect the current signal to H1 and G1 and set the fundamental component level above the threshold
setting.
4. Slowly increase the amplitude of the 5th harmonic component until the element operates. Calculate the
ratio of 5th harmonic to fundamental at which operation occurred and compare this value to the setting of
the element.
5. Check that the TRIP, PICKUP (and if selected ALARM) LEDs are on, and the following trip message is dis-
played:
SS LATCHED (OPERATED):
SS 5th Harmonic Level
6. Reduce the 5th harmonic component until the element resets. The reset level should be 97% of the oper-
ate level. Reset indicators and clear messages.
7. Repeat the above steps with a fundamental current level below the threshold setting. Ensure that the ele-
ment does not operate.
8. For timing tests, simulate an operating condition as above and apply suddenly to the relay and measure
the operating time. The time should be the same as the setting in the element.
GE Power Management 745 Transformer Management Relay
10.6 PROTECTION SCHEMES

10.6.21 VOLTS-PER-HZ 1(2)

10.6.22 5TH HARMONIC SCHEME
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