# Complication shutting off equipment with e-stop circuit



## kbsparky (Sep 20, 2007)

Are you trying to shut down all 3 panels with the press of any one E-stop button?

You might have to install some additional isolation relays to make this work. IT sounds like you are having some cross-circuit problems with the different control transformers wired together.


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## electrician1975 (Jan 14, 2011)

Basically have three emergency circuits through the emergency stops and three panels. Yes I am trying to shut down all three panels at the same time. The thing is I can shut down just one of the three with the push of a emergency stop but for some reason I cant shut down all three. Also there is three independent control transformers that I am hooking up each pair of wires too. Thanks.


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## electrician1975 (Jan 14, 2011)

They are three independent circuits. I don't believe I have any wires crossed. I have checked and checked them again.


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## kbsparky (Sep 20, 2007)

You would have to install a 4th control transformer somewhere, independent of the other 3. Have it control a master 3-pole relay that shuts off each of the other panels. The e-stop switches would have to control the master 3-pole relay, which in turn would shut down all 3 panels.

OR remove all the control transformers, and use a single independent one to control all the functions .... the isolation relay may be needed in any case.


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## electrician1975 (Jan 14, 2011)

I appreciate all your help. Can you answer one more question? Why does it shut down only one panel?


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## mattsilkwood (Sep 21, 2008)

So you have an Estop with three sets of contacts and a set of wires from each panel. Correct?
What happens if you manualy take a wire off the Estop button for panel #2 or #3? If the panel shuts down then the contacts are stuck, if it doesn't shut down then it's wired wrong.


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## kbsparky (Sep 20, 2007)

Why would it shut down any more than the one? You have different control transformers ... wired in parallel? You remove the shunt on one of the panels, and that one shuts down? 

You definitely have some cross-circuit problems with all those control transformers connected together ...

Isolation relay will fix the problem.


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## electrician1975 (Jan 14, 2011)

It isn't momentary emergency stops They are maintain contact emergency stops.


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## electrician1975 (Jan 14, 2011)

Thank you I will try that.


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## mattsilkwood (Sep 21, 2008)

kbsparky said:


> Why would it shut down any more than the one? You have different control transformers ... wired in parallel? You remove the shunt on one of the panels, and that one shuts down?
> 
> You definitely have some cross-circuit problems with all those control transformers connected together ...
> 
> Isolation relay will fix the problem.


 It's pretty simple, you have a contact block for each panel you are shutting down.


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## electrician1975 (Jan 14, 2011)

I have a contact block for each panel I am shutting down. Go back to the original post and read again please. I stated that in my original post. Thanks for your help!!!


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## electrician1975 (Jan 14, 2011)

I love your quote


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## Big John (May 23, 2010)

mattsilkwood said:


> ...If the panel shuts down then the contacts are stuck, if it doesn't shut down then it's wired wrong.


 I think this is your answer.

It sounds like you have three totally independent e-stop circuits. Transformer, conductors, contact block, shunt trip for each circuit is separate from the other two.

There is no reason putting all the contact blocks on one e-stop plunger should affect the operation of all the circuits if they are wired correctly and all your contact blocks work. Are these contact blocks stacked on the switch? I'm wondering if the plunger isn't getting aligned properly. Something to check: Is it always the 1st one in the stack that works, and the other two never do?

-John


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## Wirenuting (Sep 12, 2010)

1 wire in 1 wire out,, 1 thing currently shuts down,, no interlocking relays and you have been doing this how long?

:/


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## varmit (Apr 19, 2009)

You say that you have checked that there are no connections between the three separate e-stop circuits?

If so:
A. Check the contact blocks and see if the contact blocks, on the buttons, are being moved by the push buttons. On some brands, if too many contacts are stacked, they sometimes will not operate. Some brands also require a small plastic "coupling" to link the plunger shafts, of the contact blocks together.

B. Are the e-stop conductors routed with other energized conductors for a long distance? If the e-stop relay is very low current, or solid state, there may be enough inductive voltage on the e-stop conductors to prevent the relay from dropping out.

C. As someone else said " try lifting the wires from the push buttons and see if the e-stop relay drops out. The contacts, even if new, can be faulty.

D. Check the relay terminations.


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## firelient (Dec 15, 2010)

Don't know what type contacts you are using, but I do know Square D type has different length plungers that are used for push pull start/stop buttons.. Just a thought. Good luck


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## John Valdes (May 17, 2007)

All three E-Stops must have the same control source. All you need to do is make sure all three are wired in series and each E-Stop button opens the control circuit in each panel.

source - NC - NC - NC. Thats all there is to it.

You can also use a relay to shut down the panels. Use the NO contacts on the E-Stops and have the contact closure turn on a relay. Then you just use NC relay contacts to accomplish the shut down (open control circuit) of the panels.


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## mattsilkwood (Sep 21, 2008)

John Valdes said:


> All three E-Stops must have the same control source. All you need to do is make sure all three are wired in series and each E-Stop button opens the control circuit in each panel.
> 
> source - NC - NC - NC. Thats all there is to it.
> 
> You can also use a relay to shut down the panels. Use the NO contacts on the E-Stops and have the contact closure turn on a relay. Then you just use NC relay contacts to accomplish the shut down (open control circuit) of the panels.


 That's backwards to everything I've ever seen. You still wire the Estops like you normally would, through the NC contacts. This is used to hold the safety relay in, you would wire the actual machine stop circiuts through NO contacts on the relay. That way if you have a bad relay the machine won't start. 
The way you described if you have a bad relay the machine will fail to stop if you have an emergency condition.


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## Wirenuting (Sep 12, 2010)

There are several ways of doing what he needs. 
The OP is unsure why his 2 wire control is not working. 

He can, install a control transformer that feeds his new E-stop, and then goes to each starter and works the relay. That option gives him a complete shut down on each start circuit. 
But option 2 is to install a control transformer that is used for all 3 starter controls. A break or fault in 1 machine renders all 3 in the off/safe condition. 

I would think that he wants a complete process stop for emergency use only. 
This remote E-Stop must be capable of rendering his hand control start useless. 
He must take into account what his process is and were any potential fault may occur in his new circuit. A fault in his e-stop circuit can "start" a machine if just an interposing relay is used. 

Stop & E-stops are 2 different conditions.


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## John Valdes (May 17, 2007)

mattsilkwood said:


> That's backwards to everything I've ever seen. You still wire the Estops like you normally would, through the NC contacts. This is used to hold the safety relay in, you would wire the actual machine stop circiuts through NO contacts on the relay. That way if you have a bad relay the machine won't start.
> The way you described if you have a bad relay the machine will fail to stop if you have an emergency condition.


Backwards to some, SOP to others. All control schemes have authors and specs to follow. The use of NO contacts to energize an E-Stop relay is common.
PLC's often use "true" state for shut down. This requires a contact closure, not a contact to open. Its really up to the person who designs the control system. 
If you think it must take a NC contact to stop anything, you have no idea of the endless possibilities of control systems.

I agree for fail safe logic, a NC contact or contacts is the norm. But not the requirement in facility to facility.

Actually some would use both.


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## mattsilkwood (Sep 21, 2008)

John Valdes said:


> Backwards to some, SOP to others. All control schemes have authors and specs to follow. The use of NO contacts to energize an E-Stop relay is common.
> PLC's often use "true" state for shut down. This requires a contact closure, not a contact to open. Its really up to the person who designs the control system.
> If you think it must take a NC contact to stop anything, you have no idea of the endless possibilities of control systems.
> 
> ...


 Sure, you can stop something with NO contacts but just because you can doesn't make it a good idea. 
IMO relying on a set of contacts to make for life safety a terrible idea, I don't like to depend on a plc for the Estop either. 
One reason is if you have a problem with the Estop circuit you know it imediately because the machine won't start.


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## MDShunk (Jan 7, 2007)

FWIW, NFPA 79 requires that the e-stop mechanically open a set of contacts when it's pressed. That prohibits the reliance on the contact springs to change the contact state from NO to NC. A panel built today that uses an ordinary PLC to monitor when a set of contacts close is actually not built to NFPA 79 or ANSI B11 specs.

ANSI specs on estops mirror NFPA 79, which is why even north american panel builders have been using the dual channel safety relays for a few years now, just like the European machines have had for a good many years. Safety relays look for a set of contacts (one of two sets on each switch, actually) to go open.


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## Frank Mc (Nov 7, 2010)

Hi Guys

Here in Oz we wire E/Stop circuits normally 2 channel n/c.....n/o is used to inform the plc which e/stop has been pressed...

Frank


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## electrician1975 (Jan 14, 2011)

*Problem shutting down e-stop circuits*

Thanks all for all of your comments and responses to my situation. I figured out the problem. I had a duplicate wire feeding the control power back from the e-stop on one of the panels. I removed it and now they work.


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## tommu56 (Nov 19, 2010)

kbsparky said:


> You would have to install a 4th control transformer somewhere, independent of the other 3. Have it control a master 3-pole relay that shuts off each of the other panels. The e-stop switches would have to control the master 3-pole relay, which in turn would shut down all 3 panels.
> 
> OR remove all the control transformers, and use a single independent one to control all the functions .... the isolation relay may be needed in any case.


I would do the same or use the first machine in the sequence as the control power point.

Is there a run circuit in each machine? if so use that to enable the next one in the sequence. So stopping the first will stop all them.

One note some PB operators aren't rated for 3 or 4 blocks we ran across that with some CH 22mm ones.


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