GE 745 Instruction Manual page 253

CHAPTER 7: COMMISSIONING
7.4.7 Tap Position
745 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Table 7–2: Analog Output Calibration Results
Analog output number: __________ Analog output minimum: ______________
Analog output value: ___________
Input signal amplitude
(% of full range)
0
25
50
75
100
The analog input used to sense tap position is programmed with the
ONLOAD TAP CHANGER setpoints.
 To verify the operation of this circuit, connect a variable resistor across
terminals A3 and A4.
The resistor range should cover the full range of resistance produced by
the tap changer mechanism. The tap position is displayed in
METERING
 Adjust the resistance to simulate the minimum tap position and verify
that a "1" is displayed.
 Gradually increase the resistance up to the value which represents the
maximum tap value, verifying that the tap position indicator tracks the
resistance.
Analog output maximum: ___________
Analog output range: ____________
Expected mA output
TAP CHANGER
 
METERING
Measured mA output
S2 SYSTEM SETUP
A2
TAP CHANGER POSITION.

7–15