50Hz Instrument Transformers on 60Hz System 1

[ramski]

Hello Guys,

I'm new here and I don't know yet if there are threads related to my question.

We ordered this Medium Voltage Switchgear (15kV) from Italy and we make sure that during the ordering process we specified a 60Hz System since we are here in the Philippines; Yesterday we found out that the instrument transformer (for metering and relaying) installed are all rated 50Hz. We already informed the manufacturer about that matter and at the same time we need also your advices.

Is it ok to use it?

Thanks a lot in advance.

ramski

 

[ScottyUK]

It is likely to be fine from an electrical perspective. The higher iron losses due to the increased frequency will be offset by the reduction in iron losses due to the lower operating flux density. You may need to get the transformers re-certified if they are used in a high accuracy (i.e. fiscal) metering application.

Hopefully ScottF will give us a more detailed answer when he sees this thread.


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Sometimes I only open my mouth to swap feet...

 

[waross]

changing to 60 Hz transformers may be much less expensive that re-certifying.
respectfully

 

[jraef]

My experience is that they work fine, but they tend to run hotter and therefore don't last as long. So you may be able to use them until the correct ones arrive.

 

[scottf]

In practice, there should be no problem using units rated 50Hz on a 60 Hz system.

If you're using for revenue metering though, you may need to get them re-certified.

Regarding the comments above about heat, I can't see that being an issue. It would only be a possible concern for VTs and, unless you're loading the VTs up to the thermal burden rating (i.e. a powering application), they would not be running anywhere near their rated temp rise class. Should have no impact on their life or performance.

 

[ramski]

Thanks a lot guys!

I just one to ask one more thing, Does it affect the Ratio (output) of the Instrument Transformers?

 

[Marke]

At the higher frequency, the effective impedance of the transformer will increase slightly, so depending on the load, you may have a small reduction in the effective ratio.

I would not expect it to be enough to be an issue.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[scottf]

ramski-

No...there is no appreciable effect on the ratio, i.e. ratio error.