Stop/starting a 22kW

[edwale]

Hello Is it ok to put a timer to stop and start 22kW? The boss whats a cheaper option and is wanting to put a timer in the current DOL cicuit to start and start the 22kW. He wants to run the motor for 15 mins and stop for 15mins continiously. My concern is with this affect the motor windings? and what would be the best engineering solution to achieve this?

Thank you in advance.

 

[jraef]

I seriously doubt there will be any negative consequences from 4 starts per hour on a 22kW motor, most are going to be good for at least 10. But we don't know anything about your loading and inertia does make a difference in the starting time, which may be a factor.

The people to ask this question of would be the motor mfr. we're it a NEMA design motor, there are standard charts depicting minimum cabilities for motors, but being that you describe it as 22kW, it's not likely a NEMA design, and I don't know if IEC specifies a similar design guide. I suspect there is one though, and someone here will know how to access it.

Still, I would imagine that it will also be based on the load inertia and/or acceleration time. You should get that info first.

"Will work for (the memory of) salami"

 

[edwale]

Thats jraef.
Do I need to use two timers to have the stop/start continious operations? I guess similar to flip flop operation.

Regards

 

[LionelHutz]

Use a Omron H3CR-A timer in mode B or B2. Or, find an equivalent in whatever brand you prefer. You can wire start and stop buttons to the start and reset inputs.

You can try 2 timers but they might not work right.

 

[jraef]

Search for the term "recycle timer".

"Will work for (the memory of) salami"

 

[edwale]

Jaref Yes I have search and found the one that suits my application. It ia an electronic time. part number DMB-01-C-M24.
Once again thank you all for your porfessionalism.

Regards

 

[electricpete]

Good comments from jraef.

Link accessible from FAQ provides some info on repetitive starting limits for NEMA motors

http://www.joliettech.com/allowable_starts-intervals.htm

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(2B)+(2B)' ?

 

[edwale]

Electricpete- Thanks for that link..