I have a 3-Phase AC Motor designed for opening an electrical sliding Door, with Electromachanical and Infrared in my design. The problem I have is in the controlling circuit. Since the motor operating Direction varies by shifting the Phase on Electromechanical Releay to Electro motor, it won't work when someone activate the Infrared by crossing the door while motor is working because the infrared warn the circuit and releay disconnect the electricity completely. I need some suggestion if I can replace the Electromachanical Releay in my circuit or if there is a solution.

I really appreciate your helps.

Regards
Sadra M.

 

You say you have a 3-phase motor. Reversing is done by changing the phase sequence.
This is simply done by using a pair of contactors (large relays built for controlling 3-phase motors).
One contactor for going forward, the other for reverse.
It is very important not to energise both contactors at once (as this will short-out 2 of the phases). This is normally prevented by using mechanical and electrical interlocks.
See: attached drawing
You can replace the contactors with a Variable Speed Drive (or inverter). Much more expensive but you can then set the direction with a digital input.

 

It sounds from your description that you already have some kind of revers'er in place, and that there is a undesired action when the motor is working (closing?) and any interruption at that point will not reverse the situation.
If this is correct, then post the schematic you have to see where it can be amended.
Max.

 

When reversing the motor you need to provide a delay to enable the motor to come to a stop before reverse power is applied.

 

Not sure if the Thread Starter has a problem with the reversing of the motor or some other aspect of the door control system.
More information please!

 

Not sure if the Thread Starter has a problem with the reversing of the motor or some other aspect of the door control system.
More information please!

Deciphering this:- "it won't work when someone activate the Infrared by crossing the door while motor is working because the infrared warn the circuit and relay disconnect the electricity complete"
It sort of sounds as though the logic is not complete for open & closing sequence, when the detector senses motion by someone while the motor is in operation.?
Max.

 

... There is an interesting mechanism for braking, that is stopping, a rotating shaft. It utilizes an electromagnetic field to generate eddy currents in a disk made of copper or aluminum. Such a design could conceivably bring the motor shaft to a stop within a reasonably short interval. There is no physical contact between the electromagnet and the disk/shaft assembly. A logic circuit of minimum complexity could control the magnet.
https://en.m.wikipedia.org/wiki/Eddy_current_brake

 

There is an interesting mechanism for braking, that is stopping, a rotating shaft. It utilizes an electromagnetic field to generate eddy currents in a disk made of copper or aluminum.

Another way is to have a third contactor that shorts all three motor terminals together immediately the power contactor drops out. Interlocked, of course, so that the supply is not shorted. Even better is to inject some DC current into the windings. I have used this technique to stop dead quite large induction motors.

But I think we are going off-topic here!!

 

Maybe use a time delay relay if you are not using a PLC. If you are using a PLC I believe MAX is correct by saying its in the logic.

 

You say you have a 3-phase motor. Reversing is done by changing the phase sequence.
This is simply done by using a pair of contactors (large relays built for controlling 3-phase motors).
One contactor for going forward, the other for reverse.
It is very important not to energise both contactors at once (as this will short-out 2 of the phases). This is normally prevented by using mechanical and electrical interlocks.
See: attached drawing
You can replace the contactors with a Variable Speed Drive (or inverter). Much more expensive but you can then set the direction with a digital input.

Thanks Marley

It sounds from your description that you already have some kind of revers'er in place, and that there is a undesired action when the motor is working (closing?) and any interruption at that point will not reverse the situation.
If this is correct, then post the schematic you have to see where it can be amended.
Max.

Thanks Max

Maybe use a time delay relay if you are not using a PLC. If you are using a PLC I believe MAX is correct by saying its in the logic.

Thanks Thomas

When reversing the motor you need to provide a delay to enable the motor to come to a stop before reverse power is applied.

Thanks Alec