Contactor and overload Relay
Contactor and overload Relay
(OP)
Please can some one advice
i need to connect a 45 kVa lighting transformer to a westin house MCC 600A, incommer 400A and the availabe spare is a 60 A breaker with starter and over load relay how do i connect is it possibele to isloate both the contactor and overload relay and make use of only the breaker ?
Please can some one advice
i need to connect a 45 kVa lighting transformer to a westin house MCC 600A, incommer 400A and the availabe spare is a 60 A breaker with starter and over load relay how do i connect is it possibele to isloate both the contactor and overload relay and make use of only the breaker ?
i need to connect a 45 kVa lighting transformer to a westin house MCC 600A, incommer 400A and the availabe spare is a 60 A breaker with starter and over load relay how do i connect is it possibele to isloate both the contactor and overload relay and make use of only the breaker ?
Please can some one advice
i need to connect a 45 kVa lighting transformer to a westin house MCC 600A, incommer 400A and the availabe spare is a 60 A breaker with starter and over load relay how do i connect is it possibele to isloate both the contactor and overload relay and make use of only the breaker ?





RE: Contactor and overload Relay
You can remove the contactor, overload, and MCP breaker from the cubicle and install a standard circuit breaker in their place. The size of the breaker that is required for the 45kVA transformer will depend on your system voltage. If you are not sure of the proper size, consult the transformer manufacturer.
RE: Contactor and overload Relay
If you don't want to roll your own, you can buy a new replacement MCC feeder bucket from Eaton that will work in that old Westinghouse MCC, they have listed aftermarket buckets for that and would use the newer breakers that will undoubtedly have a higher interrupt capacity.
By the way if it's a 480V MCC, for a 45kVA transformer it would be a 70A breaker anyway and most likely a 60A breaker would nuisance trip on transformer inrush.
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RE: Contactor and overload Relay
The HMCP ciruit breaker is specifically designed to be used as a component of a combination starter that includes separate overload protection.
You cannot use a HMCP breaker separately as a feeder breaker to supply a transformer or any other load. This is because the HMCP does not have overload tripping protection. It is actually possible to flow enough continuous current through a HMCP breaker to melt it without the breaker tripping. Of course, the equipment connected downstream can also be destroyed without the HMCP breaker tripping.
When used without separate overload trip protection, the HMCP breaker will allow dangerous levels of current to flow in the circuit that will result in severe equipment damage and the risk of serious personal injury or death.
The easiest and safest solution for edetaen01 is to follow jraef's suggestion. Contact Eaton, provide them with the MCC S.O. number, and purchase a replacement MCC bucket that is fitted with a feeder breaker to supply the transformer. This will ensure that the replacement breaker has the proper interrupting rating to match the MCC specifications. As suggested by jraef, a 70 amp breaker will be required to feed the 45kVA transformer at 480 volts. Other voltages will require different breaker ratings.
RE: Contactor and overload Relay
"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies