ECN Forum Forums General Topics of the Trade General Discussion Area Why is it always a.....

C-H,
It's been probably 10 years since I've done any line work, and I can't remember the size of those oil filled transformers. My guess would be 250 KVA. These particular transformers were installed in a chemical plant out in Crosby, TX. The plant had Medium Voltage through out, and instead of underground feeders to and from their switchgear they had it strung out overhead. Well, everywhere they needed to use the power throughout the plant, the would set a pole with transformers, run conduit up the pole, and pick up the secondary side of the transformers for their motor control centers, or whatever else they used. You mentioned the poco above. These transformers belonged to the plant.
As a matter of fact, all the medium voltage work that I've done (which is not much), was done in chemical plants, with the exception of a 4160 volt pad mounted transformer that I hooked up once. It was at a research center, or engineering facility of some sort.

I've been transformed,
Doc

As everyone else here has experienced, I've had my share of "Bad Breakers" which were simply in the tripped off position.
Also had the "Bad Breakers" which were tripping due to some fault.

But, have replaced a few truly "Bad Breakers" - due to the reset mechanism being worn completely out. One common type is the old Square D XO frames.

Had lots of "Bad Breaker" scenarios where the Line side Bus connection was barbequed. More common with frames on a Plug-In Bus, but had a few Bolt-On Bus problems from loose screws on the Bus.

Bad Breaker!!! Your Grounded for two weeks!!! <bad humor>

Scott S.E.T.

Not bad humor, but humor......not bad.
Speaking of bolt in breaker problems. Went on a trouble call once. Put my meter on the neutral, and on the breaker lug where the wire was landed (oad side). Hmm....120 volts, the meter says. I walk over to the receptacle, and check it....but it's dead. Breaker live...receptacle dead....breaker live...receptacle dead....trace wire....correct circuit going to receptacle. Again....breaker live....receptacle dead. This went on for a while. I could feel the heat in the collar of my shirt. Everytiem I went back to that dead receptacle I would get even more mad. I was none to happy. Finally, I lied to the customer, told him it was fixed and left. I was hoping that some miracle would happen, and I would never have to go back to that place. I didn't care because I couldn't stand that customer. The next day, the second lie occured when my boss called and said, "Why didn't you fix that problem." I quickly replied, "It was working when I left." Famous last words. I would go to the "lie well" several times before that trouble call was over. I get back down there, and this time I pulled not just the cover, but the dead front off the panel. There right in front of me was the problem. Someone, had taken a "tech screw" and screwed it into the buss instead of the factory self threading screw. Over time the resistance in that connection burned the tab where the breaker connects to the buss (line side). Everytime I put my meter on the load side of the breaker it would push the line side down onto the buss, and I would read 120 volts. I would lift my meter probes off the breaker, and go check the receptacle only to find it dead. Before I left that trouble call, I probably lied more in that short time than I've ever lied before. I couldn't stand that guy, and every chance he got, he would back me into a corner, and I would lie my way out of it.

Guilty of one of the seven deadly sins, on that day for sure,
Sorry, Lord,
Doc

repent sinner!
say three art 406's & two art 240's

Doc,

Long story short, Bad breaker-service call. Took wire off breaker and guess what? Breaker resets. After looking around found a lot of melted wires in one room. No large load, no heaters, etc. Turned out that lightning hit a tree which hit the side of the house and melted wires in that one room. End of story for a bad breaker.