HVAC Total Power Input in kW

[Askarel27]

The client has asked me to provide the total power input in kW of a Package AC.
The electrical data for the Package AC are: MCA = 63.8 Amps ; MOCP = 90 Amps
Compressor RLA (2 ea) = 22.4 Amps & LRA = 150 ; Fan Motor = 1.7 Amps.

Note: Voltage is 460-3ph-60Hz.

Based on the above data, How can i compute the Package AC total power in kW?

 

[waross]

22.4 Amps x 2 = 44.8 Amps
44.8 Amps plus 1.7 Amps = 46.5 Amps (Assuming a single condenser and fan. Adjust the formula if there are two fans.)
46.5 Amps x 460 Volts x Root 3 = 37 KVA.
Assume a combined efficiency and power factor of 85% to 90%
@ 85% 37 KVA x .85 = 31.5 kW
@ 90% 37 KVA x .90 = 33.3 kW

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Add in a little to account for the things they didn't explicitly list, like crankcase heaters, control system, etc.

 

[waross]

Many crankcase heaters are turned off when the compressor is running but don't take my word for it. Crankcase heaters are typically used when the receiver is higher than the crankcase to prevent refrigerant from condensing in the crankcase when the compressor is idle in the event of a leaky check valve, or in systems where the back pressure rises to receiver pressure when the compressor is idle. Check your equipment diagram.

Bill
--------------------
"Why not the best?"
Jimmy Carter