Single phase motor

[JdoubleU]

I am new at working with motor, but do have an understanding of the importance of overload protection. One of the HVAC guys told be that they are looking at ventilating a classroom and was wanting to put in a small single phase motor for a fan. There reasoning is so they would not need a big starter with overloads. He said isn't there a certain size that would not require overloads. I thought all required overloads.

 

[charlie]

I am new at working with motor, but do have an understanding of the importance of overload protection. One of the HVAC guys told be that they are looking at ventilating a classroom and was wanting to put in a small single phase motor for a fan. There reasoning is so they would not need a big starter with overloads. He said isn't there a certain size that would not require overloads. I thought all required overloads.

They do except for small motors like clock motors. It seems like most of the "normal" small motors have built in protection like you would see in a disposal unit. The bottom line is that a small motor will need some type of overload protection. :smile:

 

[weressl]

They do except for small motors like clock motors. It seems like most of the "normal" small motors have built in protection like you would see in a disposal unit. The bottom line is that a small motor will need some type of overload protection. :smile:

Some times, small motors are marked 'Thermally Protected' in which case the internal thermostat opens the power to the unit and stops it.

Combination manual motor starters are available with automatic short circuit and overload elements installed.