I've come across a situation that I have never encountered before and would like to hear some educated opinions.
I have an ITE 2000 amp 5KV switch gear line-up in one of our sub stations. One of the 1200 amp 5kv draw out breakers is feeding four 750 kva transformer banks. Each bank consists of three single phase 250 kva cans connected in Delta.
It's the configuration of the cable routing that concerns me.
There are four full sets (Quad parallel) of MV-105 #350 mcm leaving the breaker load side buss.
Two sets are routed to feed three of the transformer banks in one direction at a total distance of close to 1,300'
The other two sets are routed from the sub station room in the opposite to the fourth transformer bank at a total distance of 200'
This circuit has been in service for quite a few years. We've recently had one of the transformers fail, and when we took at look at the cutouts above the bank we discovered a mess. The term kits on the MV-105 that were routed up a pole in RMC were burnt pretty good where they were landed to the ASCR cable above the cutouts. The cutouts show evidence of serious overheating and damage, and there is a decent carbon build up on all of the insulators. At the breaker end everything looked fine.
I'm concerned about the imbalance I may have on this circuit, and the harmonics it may be causing.
Any thoughts or comments would be greatly appreciated.
I have an ITE 2000 amp 5KV switch gear line-up in one of our sub stations. One of the 1200 amp 5kv draw out breakers is feeding four 750 kva transformer banks. Each bank consists of three single phase 250 kva cans connected in Delta.
It's the configuration of the cable routing that concerns me.
There are four full sets (Quad parallel) of MV-105 #350 mcm leaving the breaker load side buss.
Two sets are routed to feed three of the transformer banks in one direction at a total distance of close to 1,300'
The other two sets are routed from the sub station room in the opposite to the fourth transformer bank at a total distance of 200'
This circuit has been in service for quite a few years. We've recently had one of the transformers fail, and when we took at look at the cutouts above the bank we discovered a mess. The term kits on the MV-105 that were routed up a pole in RMC were burnt pretty good where they were landed to the ASCR cable above the cutouts. The cutouts show evidence of serious overheating and damage, and there is a decent carbon build up on all of the insulators. At the breaker end everything looked fine.
I'm concerned about the imbalance I may have on this circuit, and the harmonics it may be causing.
Any thoughts or comments would be greatly appreciated.
