Kilowatt rating vs Horsepower rating on same piece of equipment

[tim89s]

I got a spec sheet on a piece of equipment today. Under the electrical power heading it read 25kw in SI or 33.5 HP in Imperial System. It is 3 phase 240 volt. The piece of equipment is used to make small boxes, it has a few small motors and some heating elements to heat the glue. How do I size the conductors for this piece of equipment? Do I use table 430.250 or do I find the amperage from the 25kw. From the table you have to estimate, so I estimated 90 amps. From the 25kw I got 60.24 amps 250000/240 x 1.73. That a 30 amp difference. I know I am missing something but not sure what. Thanks in advance

 

[kwired]

First off 33.5 HP is not a standard size motor listed in tables near the end of art 430. But I also am guessing this may not be a single motor machine.

25 kW doesn't mean a lot when sizing conductors if there is a power factor involved either. Throw in some power factor along with teh kW and you will have a calculated necessary ampacity closer to what is in the tables in art 430.

Add: 25 kW is likely motor output power, and input power will also need to add any losses to account for motor efficiency.

 

[tim89s]

Yes there are several little motors. The power factor is .8. Even after doing the calculation I get
76 amps which is still a big difference from the amperage from the table. My issue is the panel I am coming out of will take a max 100 amp breaker. If I use the amps from the hp table I will
need a 125 amp breaker

 

[Besoeker]

Yes there are several little motors. The power factor is .8. Even after doing the calculation I get
76 amps which is still a big difference from the amperage from the table. My issue is the panel I am coming out of will take a max 100 amp breaker. If I use the amps from the hp table I will
need a 125 amp breaker

If the nameplate rating of the equipment is given as 25kW at 0.8pf, I would think that this is total input rating including motors and heaters. The combination of motors and heaters can't really be described in terms of equivalent HP. On this basis, I agree with your 76A calculation. I don't know what code issues you might need to take into account. I'm not from NEC land.