high pot or megger

[jbolen]

I have 15,000 on the primary side of my transformer and we are going to high pot the cbale.

First question what would be a good reading on the high pot.

Second question would a meagger be used on the transformer rather than using high pot on primary side??

 

[brian john]

What voltage megger?

and I would megger them both and fore go the hipot.

I assume this cable is in service?

 

[zog]

I have 15,000 on the primary side of my transformer and we are going to high pot the cbale.

First question what would be a good reading on the high pot.

Second question would a meagger be used on the transformer rather than using high pot on primary side??

In service MV cables should not be DC hipotted per ICEA, ANSI, IEEE, or NETA standards, it is considered a destructive test and may damage the cable, or at least reduce the life. PF, TD, VLF, or PD testing should be done on service aged MV cables.

As Brain said, you would always megger prior to doing an overpotential test.

There are no "good readings" when hipotting, it is all about the trends when done properly.

If you need to ask these questions, you should not be testing MV cables or transformers, call a specialist who does this for a living.

 

[rjvanwart]

Continuing Education

Continuing Education

Because a discussion of all of the factors involved with any test instruments and the various methods is beyond the scope of this format, anyone interested in this subject should review an instruction manual for insulation testers. If the accompanying original operations manual is not available I would suggest the publication Instruction Manual for Megger Insulation Testers. This manual includes instructions for connecting and operating Megger insulation-testing instruments, directions for making insulation-resistance tests on various types of electrical equipment, supplementary instructions and explanations to assist the person who makes the test, and valuable material on how to interpret insulation-resistance readings.

This last bit of information is critical to successful insulation testing. It is very important to understand what your readings are telling you.

Hope this helps. Rod

 

[K8MHZ]

In service MV cables should not be DC hipotted per ICEA, ANSI, IEEE, or NETA standards, it is considered a destructive test and may damage the cable, or at least reduce the life. PF, TD, VLF, or PD testing should be done on service aged MV cables.

As Brain said, you would always megger prior to doing an overpotential test.

There are no "good readings" when hipotting, it is all about the trends when done properly.

If you need to ask these questions, you should not be testing MV cables or transformers, call a specialist who does this for a living.

I will second that. No hipots on new pulls for the most part, either. Non-destructive testing has nearly taken over the field.

Bummer, too, as I managed to become quite proficient with a hipot before they pretty much quit using them.

 

[brian john]

Because a discussion of all of the factors involved with any test instruments and the various methods is beyond the scope of this format, anyone interested in this subject should review an instruction manual for insulation testers.
Hope this helps. Rod

While I sort of agree with this, without discussion such as these others involved in our profession that is very diversified will never have to opportunity to hear about what is out there.

Bring the questions and discussions on, just IMO utilize a firm that specializes in this work when it comes down to actually testing for several reasons.

1. We have the equipment.
2. We have the knowledge to properly perform the test involved.
3. Documentation more critical than actually doing the job, most customers have no clue what we are doing in the filed, but won't pay till the paper work is filed.