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Old March 6th, 2013, 04:27 AM   #1
kapil2910
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Sensor and contactor

Hello,
Is it possible to hold the Electrical "Contactor" using a Single pulse of Sensor...???
I want to hold the "Contactor" using a single Pulse of the sensor.. Please help.
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Old March 10th, 2013, 06:08 PM   #2
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Kapil,

Yes, it is possible to cause a contactor to be held ON due to a single pulse from a sensor. However, you will need some other equipment (other than the sensor pulse and the contactor).

Please list the equipment that you are using. Because you came to a PLC site, I assume that you are using some PLC brand, model, and catalog number. If you list the brand of the PLC, the contactor, and the sensor, and state how long that your sensor input is ON, then we can go from there to answer your question.
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Old March 10th, 2013, 11:49 PM   #3
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Yeah you could also use a set command (omron/ telemechanique) same as hold command, I think. You will also need to be able to reset the contactor using a reset command. How are you going to do this?
You may also need to create a interrupt function if the pulse is on for a short time.

If you are not using a plc the you could just do it with a normally open contact on your contactor, this will be more dependent on the speed of the pulse as contactors are a lot slower than PLC's which are inturn slower than industrial PC's
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Old March 11th, 2013, 02:06 AM   #4
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is this hard wired?
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Old March 11th, 2013, 08:49 AM   #5
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I m Not Using PLC, But is it possible to use a Latching relay between the Sensor and Contactor to hold the Contactor by single pulse of Sensor...... Please give feedback
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Old March 11th, 2013, 09:12 AM   #6
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Quote:
Originally Posted by kapil2910 View Post
I m Not Using PLC, But is it possible to use a Latching relay between the Sensor and Contactor to hold the Contactor by single pulse of Sensor...... Please give feedback
Yes it's possible, but how will you reset it once it latches?
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Old March 11th, 2013, 05:27 PM   #7
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Quote:
But is it possible to use a Latching relay between the Sensor and Contactor to hold the Contactor by single pulse of Sensor...... Please give feedback.
Okay. Without knowing the brand and catalog number of your contactor, sensor, and relay, then here is a generic version with a generic pulse stretcher. With more information from you, I could give you more information in return.

Here are some pulse stretchers at this link. I do not know which one you need because it depends on the voltage of the circuit, the sensor, the relay, and so on. A retriggable monostable multivibrator is one type of electronic circuit that can be used as a pulse strectcher. You may not need the latching relay.

http://www.arcade-electronics.com/NT...p/nte-9675.htm

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File Type: jpg Contactor Seal-in from One Sensor Pulse.JPG (29.8 KB, 76 views)

Last edited by Lancie1; March 11th, 2013 at 05:44 PM.
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Old March 11th, 2013, 07:39 PM   #8
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This version would be safer and preferred, unless your instructions specify the latching relay.
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File Type: jpg Contactor Seal-in from One Sensor Pulse R1.JPG (21.3 KB, 71 views)
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Old March 12th, 2013, 02:16 AM   #9
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Thankyou for your advices, I appriciate.....
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Old March 12th, 2013, 02:23 AM   #10
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This circuit diagram will help give you an idea on how to construct a hard-wired Latch:
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Old March 12th, 2013, 06:18 AM   #11
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How long is your sensor input pulse in the ON state (miliseconds, nanoseconds, seconds)?
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Old March 16th, 2013, 01:37 PM   #12
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It will be in milliseconds
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Old March 16th, 2013, 04:48 PM   #13
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Then you definitely will need some electronic device that can "see" or read the milisecond-range pulse and convert it to a Start signal for a contactor. A pulse-stretcher is one such device. There are probably some solid-state relays that could react fast enough to turn on when triggered by a 10 milisecond pulse.

Yes, I see that the Opto Solid-State AC Relays will trigger or operate in 0.5 cycles, and some of the DC relays have a turn on time as short as 100 microseconds (0.1 miliseconds). At 60 cycles per second, 0.5 cycles is a 8.33 millisecond pulse required to operate the solid-state relay. Make sure that your pulse is 1.5 to 2 times longer than the minimum relay turn-on time. Then you would probably need a second electro-mechanical seal-in relay to seal in your contactor.

Last edited by Lancie1; March 16th, 2013 at 05:01 PM.
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Old March 16th, 2013, 06:18 PM   #14
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Most common solid state timers may serve as a "pulse stretcher". I think Phoenix makes a din rail version of it.
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Old March 16th, 2013, 06:24 PM   #15
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Okie, a solid-state timer is a brilliant solution. I wish I had thought of that!

The timer timed output (of 2 or 3 seconds duration) could be wired directly to the contactor, with a contacor seal-in contact to hold the contactor on until turned off by a stop button.
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