GE Industrial Solutions GPS 4848_100 Users Guide (dual rectifier shelf) - Manual (Page 34)

Galaxy Power System 4848/100 with Dual Rectifier Shelf
3 - 4 Galaxy Millennium Controller Issue 5 September 2011
User Interface and Display, continued
Test Jacks A pair of test jacks allows direct measurement of the system voltage
being monitored, normally the battery voltage. This is the same point
regulated as system voltage and displayed on the front panel.