Does the power (current * watts) by an AC motor = the heat produced ?

Question

An electrical cabinet is cooled by a 18000 BTU air conditioner. The heat that is transfered from inside the cabinet to the outside of the cabinet PLUS the heat generated by the A/C system componets = to the total power consumed by the A/C system ?

Answer 1

Short answer: take the BTU rating and add about 1/6 more to account for the power consumed by the motor to get the total maximum heat rate dumped out the dump

If the A/C motor consumes 6 amps of 120 volts, then that 720 watts that needs to be dissapated somewhere, somehow. About 15% will be wasted in the motor for a single-phase motor and 85% will be do useful work (and ultimately end up as heat. 0.720 kilowatts x 3413 BTU/hr per kw = 2460 BTU/hour

Refridgeration, depending on the coolant used and the temperature range (inside versus outside the cabinet) have efficiencies of 4 to 11 or so. Let's try 7.5. So 2460 BTU/hour of electrical power consumed x 7.5 = 18,000 BTU/hour of heat moved from inside to outside. Add the 2460 (motor) + 18,000 (cooling) and there's your total heat dumped out the back of the cabinet.

Note that A/C systems often have duty cycles and all of the above is about peak rates. When the cabinet contents generated a lot of heat and its a hot day, the A/C will run for a long time. If the contents are unpowered, the duty cycle of the A/C might 10-15% of the time.

Answer 2

No, it most certainly does not.

Some, hopefully most, of the electrical energy taken by the motor will be converted to mechanical energy. That's what a motor does.

But, in the conversion process some of the energy, hopefully only a small amount, will be lost as heat.

Answer 3

Look at the electric meter outside your homeyou can find out from that. If not you have to measure the currentflow or go with manugactures spec.