service factor on motors

[stjohnbarleycorn]

When using the service factor on a motor. if the service factor is 1.15 or greater, you can use up to 125%. IF the motor has no nameplate and you use the tables, should you use the 1.15 multiplier or the 1.25. Is it different if you use the nameplate? thanks.

 

[raider1]

If you don't know what the service factor is they you must use the 115% not the 125%.

Chris

 

[Jraef]

When using the service factor on a motor. if the service factor is 1.15 or greater, you can use up to 125%. IF the motor has no nameplate and you use the tables, should you use the 1.15 multiplier or the 1.25. Is it different if you use the nameplate? thanks.

125% in relation to what? Are you referring to Motor Thermal Overload Protection or circuit Over Current Protective Devices like fuses and circuit breakers?

1.15 Service Factor means that a motor can deliver 115% power for a short duration. Technically, there is no definition of a time value, only that to do so continuously will result in decreased motor life and torque / speed specifications will no longer apply. But you can expect that to use the 115% HP, you will draw more current. If you chose to use that extra 15% in spite of the risks, factor all of your current calculations on that as the base FLC value.

But if you have no nameplate, how can you know for sure the motor has a 1.15SF?

 

[stjohnbarleycorn]

Yes that was for overload protection and I see what you are saying about the nameplate. I missed the part ( in my head) of no nameplate no service factor. thanks for the help.