GE SM-3 Regulator Panel Voltage Issue

[06Hardrocker]

I am looking for some help with an issue we are having here with a SM-3 regulator panel on a VR-1 regulator. In particular the voltage found on the voltage test studs inside the panel do not match the voltage experienced at the nearest metering point (approx. 80 yards away). We were able to get the voltage displayed on the panel to be correct by adjusting the "Load PT ratio correction %" but this did not effect the voltage on the voltage studs. We have also moved some jumpers, but none resulted in satisfactory voltage at the studs.

Any Ideas?

Thanks!

 

[waross]

Try comparing readings with a true RMS voltmeter. Anything other than a sine wave will usually cause errors in most analog meters and digital meters that are not true RMS.
Comparing the phase to phase voltage with the phase to neutral voltage on an unloaded wye:wye transformer bank will not show the proper ratio if an average responding meter is used. One of the wave forms is quite distorted and throws off the average responding meter.
respectfully

 

[dpc]

How much different are the voltage readings?

 

[06Hardrocker]

There are a few different jumper settings in the panel that are suppose to correspond to the data plate on the front. The one that relates to the 2400:120 reads ~32V LG. 2500:120 is approx 2 Volts lower than the output. The jumper setting not listed on Nameplate is approx 2 Volts Higher than actual output measured with a Fluke True RMS meter.

The GE rep is in the process of finding someone for me to contact and getting me some more Schematics.

It appears that if we correct the panel with the raios it will operate correctly. However, the Line people use these test studs all the time because most of our panels are older.

Thanks.