megger vs. hi-pot

[Designer69]

would you guys mind to help me with a breakdown of when you would use a megger test as opposed to a hi-pot and vice-versa.

I am trying to get a better understanding on this. Thanks

 

[zog]

Insulation resistance is the physical resistance from the conductor to ground. It is a measure of the actual insulation properties. Dielectric strength is the maximum voltage a dielectric can withstand without rupturing. To determine each value, tests need to be performed. To determine insulation resistance, a test commonly referred to as a megger test is done. To determine dielectric strength, a dielectric proof test (hi-pot) is performed.

An insulation resistance test should always be performed to determine if it is safe to perform a dielectric strength test.

 

[G._S._Ohm]

To determine dielectric strength, a dielectric proof test (hi-pot) is performed.

An insulation resistance test should always be performed to determine if it is safe to perform a dielectric strength test.

For Romex rated at 600 V what would be a passing score for breakdown voltage? 2400 V?

 

[zog]

For Romex rated at 600 V what would be a passing score for breakdown voltage? 2400 V?

There is no "passing score" if break down occurs, your insulation is ruined. I would not do a dielectric breakdown test on any LV equipment, nor am I aware of any standard that recommends it. Just a Insulation Resistance test @1000V for 60 seconds.

 

[ELA]

A fine point would be the difference between Hipot Dielectric Breakdown Testing
and Hi Pot Withstand Testing.

We perform Hipot Dielectric Withstand testing all the time.
Required by UL standards.

http://www.hipot-testers.com/tag/dielectric-withstand-test

 

[SG-1]

For Romex rated at 600 V what would be a passing score for breakdown voltage? 2400 V?

2400 ( that sounds close ) Volts AC RMS for 1 second. OR
1500 Volts AC RMS for 1 minute.

New manfactured assemblies receive these types of tests ( dielectric ). Dielectric testing is destructive even if the test object does not break down, the insulation is weaker after the test. This should not be done on a routine basis.


Megger tests ( DC voltages ) are used to monitor the insulation over time ( years ) watching for downward trends. The DC tests are not destructive, unless the object fails. This type of testing can be done on a routine basis.

 

[Rockyd]

Insulation test for romex with a megger? Rule of thumb is one over the voltage rating....

300 volt cable? 500 on the megger

600 volt wire? 1000 on the megger

Heat trace?? start at the lowest and work your way up.

In the oil patch, Ratheon C1,D1 heat trace gets zapped at 5000VDC for one minute on the final install prior to insulating.