Nirmalya Basu
Member
Hi to all. My problem is basically a electrical problem. I have to "ON" a 3 phase motor via two contractor coil. But how it can be done in actually. I am attach an image of my power circuit please tell me it will right or not.
How single motor can be ON by two contactor coil
- Thread starter Nirmalya Basu
- Start date
Are you trying to make a forward/reverse control for the motor?
If so, no this will not work. What you need to do is swap two of the phases on one of the coils. Most commonly this is done by taking the wire from phase A, go to the reverse contactor, then to phase C. Phase B goes to Phase B, and Phase C goes to A. Your picture is very low res and hard to read so I can't see what you're using to identify the numbers, but basically, you want to do this:
http://www.galco.com/images/moreinfo/rev_mag_motor.jpg
You will want to use a reversing contactor. Do not, I repeat DO NOT use two regular contactors. A reversing contactor is mechanically interlocked so that only one set of contacts can physically be engaged at a time. If you don't use a reversing contactor and don't wire your control circuit correctly, you will cause a phase-to-phase short circuit. Speaking of the control circuit, this is how it should be wired:
http://sub.allaboutcircuits.com/images/04062.png
If so, no this will not work. What you need to do is swap two of the phases on one of the coils. Most commonly this is done by taking the wire from phase A, go to the reverse contactor, then to phase C. Phase B goes to Phase B, and Phase C goes to A. Your picture is very low res and hard to read so I can't see what you're using to identify the numbers, but basically, you want to do this:
http://www.galco.com/images/moreinfo/rev_mag_motor.jpg
You will want to use a reversing contactor. Do not, I repeat DO NOT use two regular contactors. A reversing contactor is mechanically interlocked so that only one set of contacts can physically be engaged at a time. If you don't use a reversing contactor and don't wire your control circuit correctly, you will cause a phase-to-phase short circuit. Speaking of the control circuit, this is how it should be wired:
http://sub.allaboutcircuits.com/images/04062.png
leitmotif
Member
Drawing is hard to read no doubt about that.
I think the "power wiring" is correct he has a foward and a reverse contactor and drawing looks correct to me. What is missing is the control wiring and how the start stop switch as shown works. Bit more details that are needed are maintaining contacts on foward reverse relays and interlock contacts, overloads, limit switches etc etc.
Fully agree that a factory setup reversing starter would be good with the mechanical interlock between contactors. I like both the electrical interlocks and the mechanical.
It is a basic drawing and basically is correct and will basically work.
Dan Bentler
I think the "power wiring" is correct he has a foward and a reverse contactor and drawing looks correct to me. What is missing is the control wiring and how the start stop switch as shown works. Bit more details that are needed are maintaining contacts on foward reverse relays and interlock contacts, overloads, limit switches etc etc.
Fully agree that a factory setup reversing starter would be good with the mechanical interlock between contactors. I like both the electrical interlocks and the mechanical.
It is a basic drawing and basically is correct and will basically work.
Dan Bentler
bernie_carlton
Lifetime Supporting Member + Moderator
Dan, trace the wiring carefully through both of his contactors. It is the same phasing through both.
leitmotif
Member
Bernie
On second look I agree. May not be reversing but may be a two speed setup. Lot more detail is needed for sure.
Dan Bentler
In this statement there is no direction.
If it is understood that the motor should be "ON" from contactor 1 or from contactor 2, may be this is the wiring
Replace the poor translation with this:
Zooming in the drawing to 300%, the text below the motor symbol says "DRAW MOTOR". This is some type of winch or crane motor, so it will need to have FORWARD and REVERSE directions at the very least. As Dan said, it might also need two speeds, but that would be in addition to the Forward/Reverse contactors.
As noted by others, to produce a reversing contractor, the wiring for the left contactor needs to swap two of the phases.
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When I see this type of problem, it always makes me think it is a student homework or test question. The student usually does not know enough to explain the real problem clearly. If he really understood it, then he would already know the answer. The real question being asked is probably something like:
"Change this drawing to run the Draw Motor in Forward and Reverse (Up and Down, or In and Out) directions."
Some of these student problems cannot be accurately answered without knowing the contents of the course. This one could even be the same reversing-motor problem that SVK (India) is asking about in this thread:
http://www.plctalk.net/qanda/showthread.php?t=82503
"Change this drawing to run the Draw Motor in Forward and Reverse (Up and Down, or In and Out) directions."
Some of these student problems cannot be accurately answered without knowing the contents of the course. This one could even be the same reversing-motor problem that SVK (India) is asking about in this thread:
http://www.plctalk.net/qanda/showthread.php?t=82503
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Tom Jenkins
Lifetime Supporting Member
If you want one motor to be controlled by two different locations use one starter, and have the starter coil operated by two sets of contacts. Using two starters is a bad idea.
Nirmalya Basu
Member
OP
Thanks to all, But i don't want to run it in forward and reverse direction. As Mr. Tom said I have to "ON" a single motor by means of two different logic.Both this logic should run simultaneously and the pump motor can "ON" by the two contractor coil KV1 and KH1. Please find the total logic.
balash
Member
then as tom said why don't you replace KH and KV with miniture (auxiliary) relays and and then use their NO contact in parallel (or in series if both needs to be on for start) to control one starter contactor ?
Nirmalya Basu
Member
OP
Thank you Mr. Balash, this is a good idea. Yes I can do this. But can you explain what is the problem in this circuit?
leitmotif
Member
OK here is what I now understand
You are not reversing the motor and it is single speed.
You want to start and stop from two different locations. To do this you will still need two start and two stop switches.
You could use two relays of course but at double the cost of relays - most likely the most expensive item in the circuit - that is the main reason I would not do it.
I suppose redundancy could be an argument for this BUT if I wanted redundancy to ensure operation of vital equipment I would have two completely separate motor controls, motors and driven loads ie hydraulic pumps or ventilation equipment for mines etc where there may be life quality issues.
Dan Bentler
You are not reversing the motor and it is single speed.
You want to start and stop from two different locations. To do this you will still need two start and two stop switches.
You could use two relays of course but at double the cost of relays - most likely the most expensive item in the circuit - that is the main reason I would not do it.
I suppose redundancy could be an argument for this BUT if I wanted redundancy to ensure operation of vital equipment I would have two completely separate motor controls, motors and driven loads ie hydraulic pumps or ventilation equipment for mines etc where there may be life quality issues.
Dan Bentler
Nirmalya Basu
Member
OP
Thank you Mr. Dan how i resolve this issue do you have any sketch i think that will better for me.
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