50 Hz breaker, 60 Hz genny

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chris kennedy

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Data plate states 208y/120 60 Hz but the breaker says "Rated frequency 50 Hz". What would happen to this breaker at 60 Hz?

Thanks
 
chris kennedy said:
Data plate states 208y/120 60 Hz but the breaker says "Rated frequency 50 Hz". What would happen to this breaker at 60 Hz?

Thanks
Click to expand...
If it has electronic trips, it may not function properly, it is something only the breaker mfr can answer. If it is a basic thermal-mag breaker, not an issue from an electrical standpoint. But showing only a 50Hz label would be an indicator that the breaker may not be UL listed which, if the generator is going to be hard wired and inspected, might become problematic.
 
Dating back to 2005, Courtesy of Mr Jim Dungar, assuming this is a thermal magnetic type; it would appear that there is no appreciable effect and can be used interchangeably.
 
Thanks all. Here is a pic of the breaker, appears to be thermo mag but how does that trip button work?

 
chris kennedy said:
... but how does that trip button work?
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Probably like all of the US breakers with similar 'push to test' buttons (usually found on >150A frames). The button physically moves the same trip mechanism parts as either the thermal element or the magnetic element. This button typically operate more internal parts than does the on-off mechanical handle.
 
jim dungar said:
Probably like all of the US breakers with similar 'push to test' buttons (usually found on >150A frames). The button physically moves the same trip mechanism parts as either the thermal element or the magnetic element. This button typically operate more internal parts than does the on-off mechanical handle.
Click to expand...

Interesting, so this breaker should operate normally at 60 HZ.
 
In terms of arc interruption, its job should be easier at 60Hz.
But clearing times specified in fractions of a cycle instead of milliseconds would come out wrong.
 
Jraef said:
But showing only a 50Hz label would be an indicator that the breaker may not be UL listed which, if the generator is going to be hard wired and inspected, might become problematic.
Click to expand...

I'm still under the 2008 here so the genny and breaker only need to be 'approved'. 702.4

GoldDigger said:
In terms of arc interruption, its job should be easier at 60Hz.
But clearing times specified in fractions of a cycle instead of milliseconds would come out wrong.
Click to expand...

Everything downstream of the temp cable is protected by an
Seimens breaker at the MTS.
 
AIC of the genny is determined by some internal workings, I have the doc's here somewhere and should find them as the inspector on this job is super sharp.

Cooking dinner now so if some one else could save me the trouble and post that I would be grateful.
 
chris kennedy said:
AIC of the genny is determined by some internal workings, I have the doc's here somewhere and should find them as the inspector on this job is super sharp.
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The generator puts out SCA (Short Circuit Amps) during a fault condition, just like the utility does.
The breaker AIC (Amps Interrupting Capacity) is determined by the breaker manufacturer.

The breaker AIC must be greater than the SCA it is connected to.
 
chris kennedy said:
Its a genny, AIC is not determined by the breaker.
Click to expand...

jim dungar said:
The generator puts out SCA (Short Circuit Amps) during a fault condition, just like the utility does.
The breaker AIC (Amps Interrupting Capacity) is determined by the breaker manufacturer.

The breaker AIC must be greater than the SCA it is connected to.
Click to expand...

Yup, posting before thinking, thanks.
 
You need to know the subtransient reactance to determine short circuit capability of the generator, Xd".

Typical data may indicate something around 0.19 or 19%.

@ 208V, it looks like the contribution to fault current is around 1826A.

The fault current that a breaker ahead of the generator would see depends on which side of the breaker the fault occurs. If its on the generator side, it will see the system fault current only; if its on the HV side, then the breaker will only see the the gen fault current. Most likely the system fault current is going to be higher.
 
1. The skin effect and inductive reactance are proportional to the frequency, if a 50Hz breaker is used in 60Hz, it may cause overheating of the conductor or the copper components in the breaker.

2. It also affects the performance of the thermal-magnetic release, although not significantly.
 
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