Insulation Resistance Test Guide - 440V Generator

[Archerfish]

I couldn't find any guidelines on how to conduct IR test (Insulation Resistance) so I would like to make one specific for a 440V generator. I believe the procedure should be the same for 6.6 kV generator.

First step is lockout / tagout for the main breaker. Safety first for obvious reason.

Next is open the covers of the generator. Using a multimeter, make sure that you get zero (0) voltage across all lines.



Use a paint marker to label all wires and terminals like this.





Disconnect all wires. Again, make sure you have consistently labeled all wires and terminals.

[Archerfish]

Speaking of which, it will be better if you take a picture for an over all view like this then a detailed one. You don't want to mess up the connection.



Measure the ambient temperature and line temperature. This is for temperature correction at 20 degrees Celsius and can be useful as a reference in the future should you do IR test again.



Please don't follow these guys, they should be wearing coveralls.
[emoji3]

Depending on the capacity of the generator, switch to 500V (or 1000V) as Test Voltage and start measuring the insulation resistance for each wire. Take note of the values as you'll be using these for calculating the Dielectric Absorption Ratio (DAR) and Polarization Index (PI).



After recording all values, it is time to put everything back to its place. Consult your instruction manual for the proper torque for the terminals. If it's not available, then use a Strength Grade of 8.8 for the torque value depending on the bolt size.

Get a piece of paper and start calculating the DAR and PI values together with the temperature correction.

That's it, you're done.

[CVT]

Please don't follow these guys, they should be wearing coveralls.
[emoji3]

Ang Fogue mo bro.Archerfish!

Makinang pa ang "Korona"....

Sumbong kita sa boss mo....

[Archerfish]

Ang Fogue mo bro.Archerfish!

Makinang pa ang "Korona"....

Sumbong kita sa boss mo....

hahahahahahahahaha

That is misleading, your honor!

[Little Missy]

Pogi ni kuya [emoji7]

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[Archerfish]

Pogi ni kuya [emoji7]

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I see at least four men... who could you be referring to?
[emoji3]

[travajante]

Pogi ni kuya [emoji7]

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This thread should be retitled.[emoji4]

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[Little Missy]

I see at least four men... who could you be referring to?
[emoji3]

Him lol.

Sorry sa OT. I'm outta here.

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[CVT]

hahahahahahahahaha

That is misleading, your honor!

Thanks for sharing bro... Some of them are Greek to me, but I can probably intelligently guess a few based on my knowledge of "low power applications"....

[StockEngine]

eeng!

[Archerfish]

This thread should be retitled.[emoji4]

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And what could be a better title? [emoji3]

Him lol.

Sorry sa OT. I'm outta here.

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I remember someone (*dr.d?) said that OT adds spice!

Anyways, there's no inquiry as I just wanted to share this. I had a hard time figuring what to do first and I had to turn everything upside down just to get the necessary information. You won't be able to get any information from those dockyard people

IR test (Megger test for others) is pretty much straightforward. Except that it is recommended to get DAR and PI values since you only have the opportunity to do this during drydock or if the plant (land-based) is shutdown.

Thanks for sharing bro... Some of them are Greek to me, but I can probably intelligently guess a few based on my knowledge of "low power applications"....

It is actually the same. It is just "daunting" to do it for a generator since you don't normally do this on a regular basis. And most often than not, we would rather call a technician or a company engineer for this kind of job.

And yes, in a similar manner that I have benefited from joining this forum that I'd like to share. I know most of us here won't find it useful, this is a car forum, but hopefully someone will find it the way I intended it to be.

If I may add, most generators are connected in wye (star). If​ I'm not mistaken, it is for economical reason. You need less insulating material compared when connected to delta with the same power output. I'd like someone to confirm this or correct me on this.

[12vdc]

In Telco field, we use IR test/megger during acceptance of copper cables. There are range of values per wire gauge and not sensitive with temp, TNV is also minimal to 48-70V. We use separate device to measure splicing losses, attenuation. In transformers, i guess that is temp sensitive.

[travajante]

And what could be a better title? [emoji3]

Ummm....About Snoopy?[emoji4]



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