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Operating Manual: OP-0116
Date: July 2019
Enerpro Document No: OP-0116, Rev.A
Page 1 of 3
ECO #19-11073; Release Date: 07/23/2019
OPERATIONS MANUAL
VR31 Troubleshooting Guide
Purpose
The purpose of this document is to outline on locomotive troubleshooting of the VR31. The information in
this report should be used to incorporate into locomotive maintenance manuals.
Reference
1.
PD773, VR31 Auxiliary Generator Regulator Product Guide
Test Equipment
1.
Digital Multimeter (DMM)
2.
Banana jack test leads
Description of VR31
1.
The VR31 system is an upgraded Auxiliary Generator regulator that provides 3-stage battery
charging for legacy EMD locomotives. It works in conjunction with the EBCS-3 current sensor that
provides battery charging current feedback to the VR31. After each engine start, the VR31
transitions through the 3 stages with each stage being indicated by an LED on the front panel.
2.
Test jacks provide measurement of AuxGen voltage, battery voltage, battery current, AuxGen
field voltage, and AuxGen AC1, AC2, and AC3 voltage.
3.
If the VR31 detects a current sensor or wiring fault, a fault LED is illuminated and transition to
stage 3 is made. This is done in order to prevent battery overcharging. This fail-safe mode allows
continued locomotive operation until the EBCS-3 and associated wiring can be evaluated and
repaired.
4.
The EBCS-3 is powered from the VR31 through pin 9 and protected by a 2 amp mini-fuse, CP1.
Fuse CP1 and a spare are located near the back of the regulator module.
5.
VR31 output voltage is calibrated at the factory and is not adjustable in the field.
Normal Operation
Normal operation is indicated by illumination of one of the 3 charge stage LED’s and a nominal
AuxGen voltage range output. Stage 1 is constant battery current and Stage 2 and 3 are constant
rectifier voltage. AuxGen voltage output is measured between jacks RP (rectifier positive) and BN
(battery negative). Battery voltage is measured between jacks BP (battery positive) and BN. Battery
voltage can be 1-6 VDC lower than rectifier voltage depending on battery charging current. Battery
current is measured between jacks +IB and BN with 100 ADC scaled to 1 VDC. Nominal range output
for each stage is outlined below:
Stage 1 (Bulk):
Rectifier Voltage
~68-78 VDC
Battery Current
80-95 amps (0.80 – 0.95 VDC on front panel)
Stage 2 (Absorption): Rectifier Voltage
77.5 - 78 VDC
Battery Current
25 to 95 amps (0.25 - 0.95 VDC on front panel)
Stage 3 (Float):
Rectifier Voltage
72 - 72.8 VDC
Battery Current
0 to 25 amps (0- 0.25 VDC on front panel)
