safe stall time cold?

[ycliff]

what does the term safe stall time cold mean? - wrt electric motors?

 

[davidbeach]

The length of time a cold motor may be safely stalled. Different from (longer than) the hot stall time.

 

[LionelHutz]

To expand on davidbeach's answer, it's the length of time the motor can be "run" with rated voltage applied and the rotor not turning, due to load on it's shaft. The rated voltage and load would be applied when the motor was cold. Cold does not necessarily mean at ambient temperature - it usually means after the motor has been powered off for some length of time.

 

[powerjunx]

ycliff,

I think you're configuring a relay for a motor to enhance better discrimination.

In addition to the preceeding post above; to attain good coordination, you must define this first; SAFE STALL TIME and STARTING TIME.

Motor Characteristic;

Safe stall time less than starting time,

Safe Stall time greater than starting time.

 

[arcflash99]

When a motor is started, a significant amount of thermal heat is generated in the motor, particularly in the rotor. The rotor stall times will vary from motor to motor depending on the construction of the rotor. Many older motors had more iron in them and may have significantly longer stall times. i.e. we have plenty of 1965 vintage Louis Allis squirrel cage motors that inherently have 45-50 second cold stall times on them.

Locked Rotor time Cold- Motor at ambient temp.

Locked Rotor time Hot- Motor at it's operating temp. usually .833 times cold LR time. 10 sec LR time cold = 8.33 sec. LR time hot.