Does 120VAC Relay Can Be Used in 127VAC?

[zuozh]

There is a Brazil prj. in our Co., it is 127VAC/60Hz power supply for our electrical control device, but 127VAC relay is difficult to be got in around us. Can we supply some relay with 120VAC Coil for 127VAC control power supply system?

Tks.

 

[sibeen]

Yes.

 

[zuozh]

Dear Sibeen,

127V is a little higher than 120V, is this OK?

As we know there will be +-10% for both supply volt. & coil rated vot., or in another words, supply volt. may be high as 139.7V, but coil rated volt. can be high to 132V only. How to explain this 7.7V difference?

Tkis.

 

[itsmoked]

Ignore it. Or if you are really concerned add a dropping resistor to shave off 10V. Most relays would be fine with that small over voltage unless they are in a really hot environment or are in a poorly ventilated area.

It is also probably unlikely that you would encounter 127V. That is probably the nominal voltage and the actual voltage is probably less unless you've actually measured it.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

I'm curious. Do you use transformers wound for 127 volts connected in wye?
In North America, 127 volt rated coils are very rare. We would use a buck transformer to drop the voltage to our control relays if we were forced to design for a 127 volt system.
Have you considered using 110 VAC 50 Hz relays? They will re-rate to 110 X 6/5 = 132V.
The issue with over voltage on relays is more one of saturation than insulation failure.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[busbar]

See page 6 of

http://www.jeffersonelectric.com/s3/site/catalog/SpecialVolt.pdf

—“Latin-American Voltages” where, apparently, 460V-220Y/127V transformers are standard inventory.

 

[zuozh]

This prj. is in a power plant, client supply 1ph. AC power as 127VAC fr. its aux. power step down by its transformer, we need to supply couple of equpments fr. different venders to fit for 127VAC supply. We've got indication lights with rating as 127VAC, motor contact as 125VAC, but can't get 127VAC or 125VAC relay, only 120VAC/60Hz relay can be found.

So, I don't know if 120VAC fed by 127VAC will be problem or not?