Contactor

[laketime]

I have a customer that has a commercial grade 240 30 amp dehydrator. He wants to operate it so that if the power goes off when the dehydrator is operating that when power is restored the dehydrator does not turn back on. I am scratching my brain on what contactor/controls set up I could use that would achieve this requirement. Ideas?

 

[iwire]

I have a customer that has a commercial grade 240 30 amp dehydrator. He wants to operate it so that if the power goes off when the dehydrator is operating that when power is restored the dehydrator does not turn back on. I am scratching my brain on what contactor/controls set up I could use that would achieve this requirement. Ideas?

A contactor with one extra pole or auxiliary contact you would use that extra contact as part of the control circuit. it would latch the contactor closed.

You would have a push button to close the contactor, once closed the auxiliary contact would close maintaining power to the coil. If power went out the contactor would open and stay open until you pushed the button again.

I wire these often to shut of gas valves for kitchen equipment.

 

[GoldDigger]

The simplest thing to use would be the same circuit that you would use for a push button motor start, and just leave out the stop button.
The contactor would not normally be used to operate the dehydrator, but the start/reset button would have to be pressed once after each power outage whether the dehydrator had been operating or not.
The downside is that the contactor would have to be powered all the time.
With a smart relay interfaced to the controls of the dehydrator itself you might be able to reduce that power cost.
Basically, the start/reset button would be in series with the contactor coil and the button would be bridged by a normally open auxiliary contact on the contactor.
Just out of curiosity: Does the dehydrator have a motorized belt that could be a safety hazard? Or does he just want to force an operator to recalculate the time remaining or otherwise do something other than letting it complete its cycle?