How do I wire a timer to a reversing contactor

[JW714]

I have a project that will require a 3 phase reversing contactor to run a motor 10 seconds in clockwise, pause to allow motor to stop, then counterclockwise for 10 seconds, pause, repeat. I'm not sure how to hookup. I have a timer that has flicker mode, which alternates the output. I'm not sure how to hookup another timer for pause. Any help would be appreciated. Thanks John

 

[Reddinr]

The easiest approach might be to use a cheap programmable logic controller like the "Click" series from Automation Direct. $79 and up. The ladder software is free.

You could use a VFD and a timer if the motor isn't too big to make that very expensive. You could use a very long ramp-up time possibly. This may also require two timers depending on the VFD. I think some VFDs have a simple PLC built-in but I'm not first-hand experienced with that.

You could use a timer and a counter. The counter changes state every other "on" time of the timer. The timer would be set up to be on for 10 seconds off for pause time, repeating forever. The timer controls ON/OFF and the counter controls the direction.

I have not seen one in a long time but there used to be motorized sequencing timers with multiple switched outputs available.

If it were me, I would either go the "cheap" PLC route or use a little microcontroller board like these ones: https://www.parallax.com/product-category/basic-stamp/bs-modules/ soldered to a DIN rail proto-board or use an Arduino or other micro-controller board on a DIN rail proto-board. The languages are fairly easy to pick up, especially for the basic-stamp.

 

[markba633csi]

555 timer chip could do the delay. Or, you could purchase a second timer module. Need data sheet for your existing timer to see if it will interface
-Mark

 

[den-den]

If you are trying to use existing equipment, we need the details (schematics) of that equipment in order to help. If you are designing from scratch, there are MANY ways to do it. I have a concern that the motor will overheat after a few cycles. Not sure how many "a few" is, that depends on how big the motor is, inertia of the load etc.

 

[tq60]

I suggest converting to vfd.

Then configuring for 3 wire control.

If lazy then look at "programmable relays", these can have multiple functions with this being one of them.

Set the duration of time for cycle and it does the flashing function you need.

Connect the relay to vfd, done.

Our BP mill has vfd, once running I can flip a toggle switch and motor slows to stop (programmed rate in vfd) thengoes up to speed opposite direction.

Flip switch and it reverses again.

Vfd takes care of the hard part of the motor and relay controls the vfd.

Sent from my SM-G781V using Tapatalk

 

[JW714]

Thanks guys decided to go with three timers. The Flicker timer will alternate the output to On-Delay timers which will pause the motor.

 

[Bi11Hudson]

If you are designing from scratch, there are MANY ways to do it. I have a concern that the motor will overheat after a few cycles. Not sure how many "a few" is, that depends on how big the motor is, inertia of the load etc.

I apologize for the delay, normal for me. I must think about circuits for a while now to provide any useful idea . I often steer away from line power logic now that my mind is no longer 100%. It bothers me that my circuit might hurt someone.

Long ago, I peddled a line of circuits for model railroaders. The specific circuit I am thinking of was for a highway crossing signal. There are many different methods to getting the function, mine was based on a "flip-flop" transistor circuit with an "RC" timing circuit. Increasing the value of the capacitor, or the resistor, or both would extend the time wherever you needed. The circuits run (usually) on 5-12 volts at a very few milli-amps.

Interfacing to a line voltage device is easiest with a couple of stages of relay amplification. There is a "triac" relay that has the capacity with just a few mA input current. I personally would use such a relay because of the isolation factor. The less mixing of low voltage with line voltage, the better. The two should be kept isolated both electrically and physically. There are some basic guidelines in the NEC, but it is as much common sense as technical.

Reversing a three phase motor is no big deal. Reversing it that often and that fast is. A lot of thought needs to be put into such a circuit. It might be better to use a DC permanant magnet field motor. Depending on the load, of course. Just an option to consider.

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