Undersized Feeder

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newt

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Customer has two walk-in coolers rated at 30 amps running current, compressor fans(3 - 20 amp branch circuits), outside lights (20 amp branch circuit), block heaters for trucks (2 - 20 amp branch circuits). This panel is fed by #2 copper (100 amp fuse). Compressors are a cont. load. Motors are rated for 208 - 230 and they have 200 volts at the motors (120/208 service). Is the feeder overloaded or should they have a 200 volt motor?
 
Re: Undersized Feeder

If you have a 120/208V service, you should not have 200V at any load. There is something wrong. Does the voltage return to nominal when loads are off? You either have excessive voltage drop or possibly a connection problem.

Edit: Actually, 200V at the load of a 208V system is only about 4% VD. The motors will probably operate fine.

[ July 11, 2004, 09:22 AM: Message edited by: bphgravity ]
 
Re: Undersized Feeder

Service voltage was good at weather head,with load on.Customer blaims utility.We are trying to help customer out with some suggestions.I thought that feeder was overloaded and they should use a 200 volt motor.
 
Re: Undersized Feeder

It was my understanding that 208/230 volt motor was the range therfore 200 volt is not good.if he had asingle rated voltage then you can use +,- 10%
 
Re: Undersized Feeder

No, a 208/230 volt motor has winding arrangments for both connections. If wired at 230V it can be used on a nominal system of 220-240V approx. and if wired at 208, you can use the same tolerances, 10%+/-.
 
Re: Undersized Feeder

Originally posted by bphgravity:
No, a 208/230 volt motor has winding arrangments for both connections. If wired at 230V it can be used on a nominal system of 220-240V approx. and if wired at 208, you can use the same tolerances, 10%+/-.
Click to expand...
That may be true for 208/230 but I do not believe that is true for 208-230 rated motors.

I was told 208-230 means any voltage from 208 through 230.
 
Re: Undersized Feeder

Here is one like I am thinking of.

Motor,1 HP,General
Capacitor Start Open Dripproof Motor, HP 1, RPM 1725, Voltage 115/208-230 V, NEMA Frame 56, Service Factor 1.25, Frequency 60 Hz, Mounting Cradle, Bearings Double Shielded Ball, Thermal Protection Auto, Full Load Amps 15.0/7.4-7.4
Click to expand...
Connections for 115 or 208 through 230

Link to the motor I got the info from.
 
Re: Undersized Feeder

You state the compressor fans are each on a 20A circuit, what is their actual rating? If the refrigeration units are indeed continous load, you're at 67.5A for the compressors alone, sounds like you could easily be overloading that feeder.
 
Re: Undersized Feeder

newt:

You never said what type of problem they are having...breakers tripping, or motors going bad, ect.

Steve
 
Re: Undersized Feeder

Customers motor tripping out on overload Ithink the problem is the motor rating 208-230 (should be used on a240 service)The correct motor should be rated at 200 volts(120/208 service)
 
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