Thank you Bobby, those materials are very helpful.
I am being expected to become knowledgeable about arresters, with very little assistance from anyone else here. Basically the previous engineer that handled them, left, and I'm replacing that role. There are systems in place, and we have been using certain types of arresters, probably for decades. I'm trying to determine if there are any improvements that can be made, or if what we use is acceptable.
From what I've learned so far, the orientation/placement of the arresters are correct. I have these additional questions:
1) We have both 12kV (actually 12.47kV) and 35kV (34.5kV) distribution lines. We use 10kV (duty cycle) and 27kV arresters, respectively. We use "heavy duty" class arresters. Is there any additional considerations in terms of arresters best suited for handling lightning, or is this pretty much it?
2) Your first article mentions checking arresters for deterioration or failures. To my knowledge, due to the size of our region and number of lines/transformers/arresters, "checking" arresters is practically impossible. The only way we know if an arrester fails is if a lineman physically observes a failure, or if the device (transformer, etc) fails, they go out to replace it, and observe an additional arrester failure. This seems like a problem, but I can't see a cost-feasible way of changing this.
3) When an arrester successfully diverts a lightning strike to ground, once the strike is over, the arrester goes back into its high resistance state, and the circuit remains functional? I've read that some arresters have disconnects where they blow a charge out the bottom and thus no longer function. Am I right to assume that this occurs when the arrester becomes completely overloaded? Or when does this occur?
And when that does occur, the device is no longer arrester-protected, correct?
