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5.4 S2 SYSTEM SETUP
PATH: SETPOINTS
S2 SYSTEM SETUP
ONLOAD TAP CHANGER
[ENTER] for more
This section contains the settings to configure the tap position input. The 745 accepts a resistive input from the tap changer
control circuitry, which is used in the 745 to dynamically correct for CT ratio mismatch based on the dynamically changing
voltage ratio of the transformer. Thus, the percent differential function of the device can be set for greater sensitivity. See
Section 5.2.2 Dynamic CT Ratio Mismatch Correction on page 5–5 for more details on the tap position input.
•
WINDING WITH TAP CHANGER: Enter the winding with the tap changer. Enter 'None' for a transformer with no
onload tap changer, or to disable this feature.
•
MINIMUM TAP POSITION VOLTAGE: Enter the voltage at the lowest tap position. This is an auto-ranging setpoint
5
dependent on
S2 SYSTEM SETUP
•
VOLTAGE INCREMENT PER TAP: Enter the voltage increment for each tap. The range is affected by the setpoint.
This is an auto-ranging setpoint dependent on the
value; see ranges in the following table
ING
SETTING
MINIMUM TAP POSITION VOLTAGE
VOLTAGE INCREMENT PER TAP
•
RESISTANCE INCREMENT PER TAP: Enter the resistance increment that the 745 will see for each tap increment. The
maximum resistance value for the top tap is 5 KΩ
PATH: SETPOINTS
S2 SYSTEM SETUP
HARMONICS
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The 745 calculates the individual harmonics in each of the phase current inputs up to the 21
tion, it calculates an estimate of the effect of non-sinusoidal load currents on the transformer rated full load current. These
calculations are based on ANSI/IEEE Standard C57.110-1986, and require information that is often only available from the
transformer manufacturer's test report, including the three-phase resistance of each winding and the load loss at rated
load. The harmonic derating factor will only be valid if this information has been entered correctly.
5-32
Courtesy of NationalSwitchgear.com
ONLOAD TAP CHANGER
ð
WINDING WITH TAP
ENTER
CHANGER: None
ESCAPE
NUMBER OF TAP
ESCAPE
POSITIONS: 33
MESSAGE
MINIMUM TAP POSITION
ESCAPE
VOLTAGE: 61.0 kV
MESSAGE
VOLTAGE INCREMENT
ESCAPE
PER TAP: 61.0 kV
MESSAGE
RESISTANCE INCREMENT
ESCAPE
PER TAP: 33
Ω
MESSAGE
TRANSFORMER
LOW VOLTAGE WINDING RATING
S2 SYSTEM SETUP
LOW VOLTAGE WINDING RATING
ABOVE 5 KV
0.1 to 2000.0
in steps of 0.1 kV
0.01 to 20.00
in steps of 0.01 kV
HARMONICS
ð
HARMONIC DERATING
ENTER
ESTIMATION: Disabled
ESCAPE
THD MINIMUM HARMONIC
ESCAPE
FUNCTION: 2nd
MESSAGE
THD MAXIMUM HARMONIC
ESCAPE
FUNCTION: 2nd
MESSAGE
745 Transformer Management Relay
5.4.4 ONLOAD TAP CHANGER
Range: None, Winding 1, Winding 2, Winding 3
Range: 2 to 50 in steps of 1
Range: Dependent on
LOW VOLTAGE WINDING RATING
setpoint; see description below.
Range: Dependent on
LOW VOLTAGE WINDING RATING
setpoint; see description below.
Range: 10 to 500 Ω in steps of 1
; see ranges in the table below.
TRANSFORMER
LOW VOLTAGE WINDING RAT-
1 KV TO 5 KV
0.01 to 200.00
0.001 to 20.000
in steps of 0.01 kV
in steps of 0.001 kV
0.001 to 2.000
0.0001 to 0.2000
in steps of 0.001 kV
in steps of 0.0001 kV
Range: Enabled, Disabled
Range: 2nd, 3rd, 4th,..., 21st
Range: 2nd, 3rd, 4th,..., 21st
st
harmonic. With this informa-
5 SETPOINTS
BELOW 1 KV
5.4.5 HARMONICS
GE Multilin
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