30 S&C Instruction Sheet 661-500
Appendix C
System Line-to-Ground Voltage Calibration
To calibrate the system line-to-ground voltage:
STEP 1.
Record the voltage-sensor magnitude ratios of each voltage sensor in Table 11. The voltage-sensor
magnitude ratio can be found on the Voltage-Sensor Data Yellow card (G-6244R6, page 2) shipped with the
system.
Table 11. Voltage-Sensor Magnitude Ratios
Voltage-Sensor Magnitude Ratios
Phase 1
Phase 3
Phase 2
STEP 2.
Turn the three-phase power switch to the
Off
position and wait for 10 seconds. Using a voltmeter, measure the
voltage (Vac) at the J3 connector and record the measurements in Table 12.
Table 12. Input Voltage
Input Output Voltage
Phase 1 (J3-1 to J3-2)
Phase 3 (J3-3 to J3-4)
Phase 2 (J3-5 to J3-6)
STEP 3.
Turn the three-phase power switch to the
On
position and wait for 10 seconds. Using a voltmeter, measure the
voltage (Vac) at the J2 connector and record the measurements in the Table 13.
Table 13. Analog Output Voltage
Analog Output Voltage
Phase 1 (J2-20 to J2-17)
Phase 3 (J2-20 to J2-19)
Phase 2 (J2-20 to J2-18)
STEP 4.
Calculate the system line to ground voltage using the formula below. Record the line-to-ground voltage for each
phase in Table 14.
System line-to-ground voltage = 1.006
×
Input Voltage
(Table 12)
×
Voltage-Sensor Magnitude Ratios
(Table 11)
Table 14. System Line-to-Ground Voltage
System Line-to-Ground Voltage
Phase 1
Phase 3
Phase 2
STEP 5.
Calculate and record the adjust voltage-sensor ratios for each phase in Table 15. These adjust voltage-sensor
ratios must be entered into the RTU to offset unit-to-unit variations in the charger when voltage sensors power
the charger.
Adjust voltage-sensor ratios
=
System line-to-ground voltage
(Table 14)
∕
Analog output voltage
(Table 13).
Table 15. Adjust Voltage-Sensor Ratios
Adjust Voltage-Sensor Ratios
Phase 1
Phase 3
Phase 2