Circuit Breaker testing

[UtilityGy]

Hi,

I had posted a similar post in the past as well. Unfortunately, I have not been able to find proper litrature issue on this subject. I am sure, some of you have come across this and will be able to advise me some useful input.

1. Partial discharge or Corona test= Is this traditionally a type( Design) test or a production test. Is it mandatory to do this test.

2. Doble GST & UST testing- is this a design test or a production test. Is this mandatory in either of the categories.

Thanks

 

[manning225]

Partial Discharge testing. Could be either type testing or a production test though relying on a type test alone would not be wise. Manadatory only if the customer specifies the test! (EU law - US may be different) IEC 60270 specifies methodology but not levels. Levels are specified by purchaser usually 5-10 pC. Some manufacturers test individual components but not assembled switch - not recommended but happens because of woolly specifications.

 

[UtilityGy]

Thanks Steven

 

[mgtrp]

My experience from working as a test technician at a switchgear manufacturer in an IEC country was that EVERY completed switchgear that we sent out was PD tested, regardless of whether this was requested by the customer (the only difference was whether we posted them the test report).

My observation of North American practices in my new home as a customer is that it would be very unusual to carry out PD testing at the factory.

 

[climb1]

PD testing is not mandatory for production testing, yet. i agree that it is not good as a type test. i have used measuring devices and found that they are not limited to PD, but also may tell if bolts are not torques properly. the PD measurements did not pick up until higher levels, above 80kv. i have heard conversations in switchgear meetings regarding making it a standard production test.

The GST and UST testing is the power factor testing. i do not find value in the power factor testing with gas circuit breakers. it was a test designed for the insulation for OCB's. the test is not required in type testing or production of SF6 CB's.

i am interested to know other points regarding this testing.

 

[protocolo]

Each manufacter has his own spewcification, upon Circuit Breakers , GIS and insulated equipments must be carried out HV test on site.for example for a equipment of 145 KV be aplied 235 KV x 1min
partial discharge measurements-> o,5 pc
but IEC could accept some peaks until 10 PC.

 

[CanadianKid]

PD is typically a factory test which is difficult to replicate as a field test because of the sensitivity of the measurement (5pC is a very small amount). A high voltage or medium voltage station emits tremendous noise, all of which is seen by PD measuring equipment. I have sold Biddle PD equipment to transformer, breaker and cable factories, and even within the factories, we had to go to great lengths to eliminate the ground and airborne PD noise.

Even if one was able to perform the measurement, the source test voltage must be PD free, which is another difficulty.

PD is an excellent tool, and many are making advances in its use in the field, but to date, it is not a commercially viable test, (as seen in Canada to date)

Use of Insulation PF (Doble) is used by many, and not used by many more. I know of 2 major Canadian utilities who have stopped using this test on breakers (other than older style)because of the lack of conclusive results over the years. The small capacitance of the breaker sections makes it difficult (exception are the gradient capacitors)to get meaningful results.