26KVA for 1 sec Fault rating
26KVA for 1 sec Fault rating
(OP)
A stupid question,
I was asked what (in the field of control panels and MCC's) what 26Kva for 1 sec was, I know its a fault rating I wonder if any of you would be so kinda to tell me what it means, I thought it was something to do with the max KVA a given setup (busbar system) would take before failing.
and how do you measure it?
I was asked what (in the field of control panels and MCC's) what 26Kva for 1 sec was, I know its a fault rating I wonder if any of you would be so kinda to tell me what it means, I thought it was something to do with the max KVA a given setup (busbar system) would take before failing.
and how do you measure it?





RE: 26KVA for 1 sec Fault rating
RE: 26KVA for 1 sec Fault rating
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: 26KVA for 1 sec Fault rating
RE: 26KVA for 1 sec Fault rating
MCCdesigner,
In the context of a low voltage MCC, there are two ratings that it (26kA) could pertain to.
Bus bracing, which is the ability of the bus bar supporting structure to keep the bars from coming together under a fault condition of that magnitude. However, that is usually not expressed with a time duration, it is just the magnitude, and most MCCs on the market are not built for any less than 42kA that I know of.
Withstand rating, which is the rating of the entire system, including all devices inside, to withstand the forces of 26,000 amps attempting to flow through a fault before an upstream device has a chance to clear it. So if there is a circuit breaker feeding the MCC, they know that the breaker has a "let through" of 26kA, and a clearing time of under 1 second, so they want to ensure that everything downstream from that breaker can withstand that much current for that long without becoming a projectile. In an MCC then, either you have a current limiting main breaker or fuses that would limit fault current to levels that individual downstream components can handle. An alternative would be for every downstream device to be capable of that fault level.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: 26KVA for 1 sec Fault rating
respectfully.
RE: 26KVA for 1 sec Fault rating
RE: 26KVA for 1 sec Fault rating