Generator Frequency Meters

[Tuxedo]

Maybe some of you generator experts can shed some light on a problem we have with our generator. The generator services a small ski hill with 1 chair lift - off grid.
The generator is 480 V, Y and seems to work fine however, we have had problems with keeping a frequency meter operating. We think it's a case of having a meter with the wrong rating. The meter is a Modutec Inc. Cat # R3PB-FRQ-55/120-20 - from what we can gather reading the label it is rated at 55 Hz and 120 Volts. It aslo has a rating of 800 Volts to ground. It looks like there is a large resistor or Inductor attached to the meter also ( not familiar with the workings of a freq. meter). My question is can w3e use a meter with this rating on a 480 volt Y generator? Thanks in advance for your input.

 

[electricpete]

I haven't looked in detail but I'm pretty sure from your description the answer will be NO.

The rating of 120v applies across the input of the device. If you apply 480 or 480/sqrt(3) volts to the input you will likely draw more current and fry the device.

I am guessing that the 800v is the rating of voltage to ground, NOT voltage applied between terminals.

 

[Tuxedo]

Thanks for the response electricpete. You're correct the 800v rating is to ground. The meter is hooked up from Hot to Neutral = 277 volts. There is a power resistor on the exterior of the meter that is "open" We've torn apart the meter and there is a smaller power resistor that is "open" also. None of the markings are legible. We've been experimenting with Power resistors and the internals of the meter seem to be OK. I'm assuming the power resistor on the outside of the meter case was used as a voltage divider to get 277 V down to 120 V but thats just an assumption at this point. I had to proceed on assumptions though. We will probably add a power resistor to the new meter and use that and double check the frequency with a meter.

 

[busbar]

In most AC gear in ANSI regions, it is customary to use meters with a 120V {and/or 5-amp} ratings, and install potential/current transformers to scale larger quantities.

 

[jbartos]

Suggestion: It is advised to exercise the utmost caution to connect equipment rated at the lower voltage to the higher voltage. Usually, safety codes, industry standards and the manufacturer tech supports are necessary to be safe.

 

[jbartos]

Suggestion: Visit

http://www.thomasregister.com

and type Meters: Frequency under Product or Service that will return 58 companies to contact directly regarding your frequency meter service or replacement.

 

[armstrongpower]

Tuxedo

Seems that the meter is damaged, try buying the same size
to fit your existing panel and advice the Madutec factory
the supply voltage you will be feeding to the meter,
either L-L (480v) or L-N (277v). Then you will receive
the meter to properly work with.

Good luck. And happy new year.