Breaker testing for insurance requirements
Breaker testing for insurance requirements
(OP)
Insurance company wants us to test all of our unit substation secondary breakers. They all GE AK breakers 600 and 1200A. They have all been retrofitted with AC Pro trip units within the last 10yrs.
Should we use primary or secondary injection for the tests. I don't think primary is a good option. They were primary tested after retrofit, and I don't want to risk damage to the contacts because we don't have many spares, and new contacts are becoming hard to find and GEXPRO has very long lead times. I believe the secondary testing will satisfy the requirements without the risk of damage.
Should we use primary or secondary injection for the tests. I don't think primary is a good option. They were primary tested after retrofit, and I don't want to risk damage to the contacts because we don't have many spares, and new contacts are becoming hard to find and GEXPRO has very long lead times. I believe the secondary testing will satisfy the requirements without the risk of damage.






RE: Breaker testing for insurance requirements
RE: Breaker testing for insurance requirements
RE: Breaker testing for insurance requirements
Side note, I stock those contacts, along with 5 million other obsolete switchgear parts.
RE: Breaker testing for insurance requirements
smallgreek-
I understand your comment, but we test the trip circuits and other aspects of those 500 kV breakers. We test the relays. We test the controls.
Low voltage power circuit breakers shove all these into one package. Primary injection testing gets the mechanism, the trip coil, and the trip unit.
old field guy
RE: Breaker testing for insurance requirements
RE: Breaker testing for insurance requirements
RE: Breaker testing for insurance requirements
The electrical utility (big one) that I used to work for tested CT's on initial commissioning. After that, the only ones regularly tested were those used in high impedance bus differential schemes. That is, unless something went wrong.
Another big electrical utility I did contract work for had us test all the CT's on ALL their transmission equipment. We found a couple of CT's in OCB's that had shifted and now had a shorting path through the window, resulting in very low saturation voltages. One of these became the 'smoking gun' in an investigation following a scheme misoperation, tripping on a through fault when it quit contributing current. But that was two out of hundreds...
Then a major manufacturer with a German name had a problem with water ingress into external CT's on GCB's. We tested THOSE regularly because the water damage caused the saturation to go down, too.
old field guy
RE: Breaker testing for insurance requirements
RE: Breaker testing for insurance requirements
Regardng damage to your breaker, there are some concerns about primary injection testing of your ST and INST trip functions. The best method is to test LT with primary injection and the other functions via secondary injection. This method is often refered to as "Primary injection with secondary verification"
RE: Breaker testing for insurance requirements
Don't try and guess what they want
RE: Breaker testing for insurance requirements
RE: Breaker testing for insurance requirements
These are:
mechanical operation
verification of the calibration of overcurrent releases (requires primary injection)
verification of the operation of undervoltage and shunt releases
dielectric tests
verification of clearances