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5 SETPOINTS
The 745 also calculates the total harmonic distortion of the phase current input signals. The band of frequencies over which
this calculation is made can be changed to be more selective than the default 2
•
HARMONIC DERATING FUNCTION: Enter "Enabled" to enable the harmonic derating factor calculations.
•
THD MINIMUM/MAXIMUM HARMONIC NUMBER Enter the minimum/maximum harmonic number of the frequency
band over which total harmonic distortion is calculated.
PATH: SETPOINTS
S2 SYSTEM SETUP
FLEXCURVE A
[ENTER] for more
Three programmed custom FlexCurves™ can be stored in the 745 as FlexCurve™ A, FlexCurve™ B, and FlexCurve™ C.
This allows the user to save special curves for specific applications and then select them as required for time overcurrent
element curves. The custom FlexCurve™ has setpoints for entering the times-to-trip at various levels of pickup. The levels
are as follows: 1.03, 1.05, 1.1 to 6.0 × PU in steps of 0.1, and 6.5 to 20.0
•
CURVE TRIP TIME AT n
that follow sequentially correspond to the trip times for the various pickup levels as indicated above.
PATH: SETPOINTS
S2 SYSTEM SETUP
VOLTAGE INPUT
[ENTER] for more
The 745 provides a voltage input for the purposes of energization detection (for the Energization Inhibit feature of the per-
cent differential element), overexcitation protection (the Volts-per-Hertz 1 and 2 functions), and frequency protection (the
Underfrequency, Frequency Decay, and Overfrequency functions). Note that the frequency elements will use the Winding 1
Phase A current input if voltage is not available.
•
VOLTAGE INPUT PARAMETER: Enter the winding and phase of the voltage connected to the voltage input.
•
NOMINAL VT SECONDARY VOLTAGE: Enter the nominal secondary voltage (in volts) of the voltage transformer.
•
VT RATIO: Enter the ratio of the voltage transformer.
GE Multilin
Courtesy of NationalSwitchgear.com
FLEXCURVES
ð
CURVE A TRIP TIME AT
ENTER
1.03 x PU:
ESCAPE
CURVE TRIP TIME AT
ESCAPE
1.05 x pu:
MESSAGE
↓
CURVE TRIP TIME AT
ESCAPE
20.0 x pu:
MESSAGE
PU: Enter the trip time for n = 1.03. 1.05,..., 20.0
×
VOLTAGE INPUT
ð
VOLTAGE SENSING:
ENTER
Disabled
ESCAPE
VOLTAGE INPUT
ESCAPE
PARAMETER: W1 Van
MESSAGE
NOMINAL VT SECONDARY
ESCAPE
VOLTAGE: 120.0 V
MESSAGE
VT RATIO:
ESCAPE
1000:1
MESSAGE
745 Transformer Management Relay
nd
st
to 21
harmonics.
FLEXCURVE A(C)
Range: 0 to 65000 ms in steps of 1
0 ms
Range: 0 to 65000 ms in steps of 1
0 ms
Range: 0 to 65000 ms in steps of 1
0 ms
PU in steps of 0.5.
×
PU for FlexCurve™ A(C). The messages
×
Range: Enabled, Disabled
Range: W1, W2, W3;
Van, Vbn, Vcn, Vab, Vbc, Vca
Range: 60.0 to 120.0 in steps of 0.1
Range: 1 to 5000:1 in steps of 1
5.4 S2 SYSTEM SETUP
5.4.6 FLEXCURVES™
5.4.7 VOLTAGE INPUT
5-33
5
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