GE Multilin
745 Transformer Management Relay
8-29
8 COMMISSIONING
8.5 PROTECTION SCHEMES
8
Hence, the phase current will be three times the pickup setting.
2.
When the element operates, check that the Trip and Pickup LEDs are on and one of the following is displayed:
3.
Reduce the current until the element resets. The reset level should be 97% of the operate level. When the element
resets, the Trip and Message LEDs should remain on if the
W1 NEG SEQ INST OC TARGET
was selected as "Latched".
Otherwise, only the Trip LED should remain on.
4.
Reset indicators and clear messages.
OPERATING TIME:
Using the setup in Figure 8–9: General Test Setup on page 8–18 with the Interval Timer enabled, set the current level to 1.5
times the operate level of the element and apply suddenly by closing the double-pole switch. Record the operate time and
compare to the
S4 ELEMENTS
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NEG SEQ OC
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W1 NEG SEQ INST OC
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W1 NEG SEQ INST OC DELAY
setting.
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.
8.5.13 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 mini-
mum 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 super-
vision is enabled, or else the detectors will not operate.
Figure 8–12: 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
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FREQUENCY
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UNDERFREQUENCY 1
settings menu.
LATCHED
W1 Neg Seq Inst OC
OPERATED
W1 Neg Seq Inst OC
NOTE
NOTE
Содержание TRANSFORMER MANAGEMENT RELAY 745
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