I'm still on with a periodic at the moment, and we were feeling brave today and decided to have a go at tackling the main switch room.
Many of the DBs are fed from here, and it appears that the only over current protection for the submains cables is provided by these contactors.
I have encountered them once or twice before, but I am not fully familiar with their operation.
We are trying to determine their rated tripping current, but AFAIK they are adjustable, and it's proving a bit arkward.
These are all single phase supplies, and at a guess, we think the overloads are set for about 50A
Here are the adjusters. They are the brass bits which normally sit in a pot of mineral oil, but the cover is missing from a couple. The brass bits can be wound in and out, and there is a scale stamped ono them, but it unfortunatly goes from A - G rather than the actual current rating.
Is the lack of oil likely to affect the tripping characteristics too?
There are some other contactors in there as well. One is about twice the size, and is stamped at 130A SP. There are some bigger TP ones as well.
Sorry about the photo qualtiy. I forgot my camera again and had to use my phone.
Many of the DBs are fed from here, and it appears that the only over current protection for the submains cables is provided by these contactors.
I have encountered them once or twice before, but I am not fully familiar with their operation.
We are trying to determine their rated tripping current, but AFAIK they are adjustable, and it's proving a bit arkward.
These are all single phase supplies, and at a guess, we think the overloads are set for about 50A
Here are the adjusters. They are the brass bits which normally sit in a pot of mineral oil, but the cover is missing from a couple. The brass bits can be wound in and out, and there is a scale stamped ono them, but it unfortunatly goes from A - G rather than the actual current rating.
Is the lack of oil likely to affect the tripping characteristics too?
There are some other contactors in there as well. One is about twice the size, and is stamped at 130A SP. There are some bigger TP ones as well.
Sorry about the photo qualtiy. I forgot my camera again and had to use my phone.