Electrical Load List

[Charz]

The Peak load is estimated based on (100% x Continuous Loads) + (30% x Intermittent Loads) + (10% x Standby Loads). Typically this is how load list is estimated in Oil & Gas Industry. Say If I have 10kW load as continuous loads, 75kW Motor as Intermittent load and No standby loads, the peak load comes around (100% x 10kW) + (30% x 75kW) -> 32.kW

Should I size my transformer based on this 32.kW? here the single motor even if it operates for 1 hour, the transformer sized based on this peak load could be overloaded.

 

[Dsg319]

The Peak load is estimated based on (100% x Continuous Loads) + (30% x Intermittent Loads) + (10% x Standby Loads). Typically this is how load list is estimated in Oil & Gas Industry. Say If I have 10kW load as continuous loads, 75kW Motor as Intermittent load and No standby loads, the peak load comes around (100% x 10kW) + (30% x 75kW) -> 32.kW

Should I size my transformer based on this 32.kW? here the single motor even if it operates for 1 hour, the transformer sized based on this peak load could be overloaded.

I would size it based off of the peak of everything it could have loaded at once. But I’m no engineer.

 

[tortuga]

Say If I have 10kW load as continuous loads, 75kW Motor as Intermittent load

If this falls under the NEC or your just using the NEC:
For oil and gas equipment the feeder conductors (presumably this is all outdoors) would be sized per NEC 225.5, which pulls in a article 220 load calc (see 220.40 and 220.50)
Panelboards overcurrent protection is per 408.36.

The Transformer does not need to be sized based on a article 220 load calc, but it needs overcurrent protection per 450.3, typically this overcurrent protection is the feeder disconnect.

The 75kW motor would need to be converted to horespower, the the load calculated per article 430 and its tables (430.6)

 

[don_resqcapt19]

The Peak load is estimated based on (100% x Continuous Loads) + (30% x Intermittent Loads) + (10% x Standby Loads). Typically this is how load list is estimated in Oil & Gas Industry. Say If I have 10kW load as continuous loads, 75kW Motor as Intermittent load and No standby loads, the peak load comes around (100% x 10kW) + (30% x 75kW) -> 32.kW

Should I size my transformer based on this 32.kW? here the single motor even if it operates for 1 hour, the transformer sized based on this peak load could be overloaded.

A general rule of thumb for starting motors without excessive voltage drop from the starting current is that you use the motor kW as the minimum kVA of the transformer.

 

[tom baker]

A general rule of thumb for starting motors without excessive voltage drop from the starting current is that you use the motor kW as the minimum kVA of the transformer.

What our POCO allows is 1kw per horsepower. And they have limits on across the line starting for large motors.