Motors and Power Savings

The power consumed by a motor is strongly related to the torque/speed relationship of the load. The above post gives no details so it will be extremely difficult for any reader to offer advice at this stage.

Hello,

Please first check the total load on your motor, if its takes less than 10 to 12 Amps. then think for replacement.

The mechanical power (related to torque and speed) will need to be the same, if efficiency of a smaller, newer motor running at full load is better, it may be possible to use less electrical power (related to voltage and current) and hence save a small amount of money..

So, work out the power consumed now, if it's under 15kW you can use a 15kW motor.

That's assuming the speed, torque curve, number of starts per hour etc are appropriate. I'd guess that most engineers wouldn't bother changing over.

for any equipment to start it requires higher torque than normal running, so you have to be sure that smaller motor can start the equipment.

the power consumption will be =1.732* V* I* cos phi/ motor efficiency at running load

V Voltage will remain same for both motors

I current may change

power factor cos phi also may change

So donot go for current reduction alone check I* cos phi. For a low power factor motor current will be higher for the same load.

motor efficiency at running load should be the key factor besides starting capability to decide about motor changing decision.

If 400V (???) then 20A is close to no load so the load may be only af ew kW.

If you use a smaller motor this will have a lower current since its no load current is lower.

This will reduce kVA but of course the kW will be the same if same job at the same speed (Smaller motor will run slower normally for same load)

Power saving seems marginal but kVA demand will be lower.

what is the driven equipment? pump?pl give more details.