# 4 wire e-stop



## LogicDB (Feb 12, 2010)

I'm looking at a 4 wire e-stop. The drawings (that show the connections between controllers) are so bad that I can't tell the purpose of the 4 wires. Anyone wanna shed a little light for me?
Thanks.


----------



## Jlarson (Jun 28, 2009)

LogicDB said:


> I'm looking at a 4 wire e-stop. The drawings (that show the connections between controllers) are so bad that I can't tell the purpose of the 4 wires. Anyone wanna shed a little light for me?
> Thanks.


Maybe they are lighted e-stops.


----------



## Bob Badger (Apr 19, 2009)

LogicDB said:


> I'm looking at a 4 wire e-stop. The drawings (that show the connections between controllers) are so bad that I can't tell the purpose of the 4 wires. Anyone wanna shed a little light for me?
> Thanks.


It sounds like you are wiring into a safety relay which can require four wires for two contacts.

It is for redundancy

http://www.safety-relay.com/monitoring_relays.html.


----------



## LogicDB (Feb 12, 2010)

They are lighted (plc output), and they also switch an input to the plc. 

The four wires that I am looking at are 1 set through the e-stop, and 1 set that seems to jumper through. I have to take a better look at the relay tomorrow. I'm buried with other things, and didn't have a chance to take a good look yet.


----------



## LogicDB (Feb 12, 2010)

What is the safety relay looking for?


----------



## MDShunk (Jan 7, 2007)

Pretty much all guard circuits and e-stop circuits now are 4-wire. They call it "2-channel". Essentially just two sets of contacts, is all.

Before the days of safety relays, guys still used a lot of 4-wire e-stop and guard circuits. One set of contacts went to a light (to show what guard switch or e-stop switch was keeping the machine from running), and the other contact went to the run relay.


----------



## LogicDB (Feb 12, 2010)

Terminals

es1
es2
es3
es4

The es1 and es3 go through the estop contact, and the es2 and es3 show a jumper.

Horrible drawings, and it shows an unconnected relay coil.

Honestly, this should be no big deal, these guys have wretched engineering details.

I'll look again tomorrow, I'm embarassed to even be asking about this!


----------



## MDShunk (Jan 7, 2007)

LogicDB said:


> Terminals
> 
> es1
> es2
> ...


Yeah, ES1 and ES2 are the "line side" of both safety circuits, and ES3 and ES4 are the "load side". They're jumpering out one circuit, the way it seems. That sounds like how Schmersal labels their safety stuff. 

Here's a decent link on how A-B does it: http://www.ab.com/en/epub/catalogs/3377539/5866177/3378080/3384290/3384298/


----------



## LogicDB (Feb 12, 2010)

Makes sense, but I am missing something. I can see that one set is bypassed, for whatever reason, but ultimately I can't hook up the es1, es2, es3 and es4 terminal to terminal (from panel to panel) without them being in parallel- that's where I'm confused.


----------



## Jlarson (Jun 28, 2009)

Eaton makes a contact something like that. I think they call it a self monitored contact. Might want to look that up with Google.


----------



## MDShunk (Jan 7, 2007)

LogicDB said:


> Makes sense, but I am missing something. I can see that one set is bypassed, for whatever reason, but ultimately I can't hook up the es1, es2, es3 and es4 terminal to terminal (from panel to panel) without them being in parallel- that's where I'm confused.


If you have more than one e-stop, you wire them in series. Hopefully you won't be a moron, and you'll home run each e-stop to the terminal bar in the cabinet. Your es1 will be on the first terminal in that series of e-stops, and your es3 will be on the last terminal in that series of e-stops.


----------



## Jlarson (Jun 28, 2009)

MDShunk said:


> If you have more than one e-stop, you wire them in series. Hopefully you won't be a moron, and you'll home run each e-stop to the terminal bar in the cabinet. Your es1 will be on the first terminal in that series of e-stops, and your es3 will be on the last terminal in that series of e-stops.


I gather for some reason that you don't like just daisy chaining each e-stop. :laughing: I much prefer each one run back to the cabinet individually too. Gives you more options.


----------



## MDShunk (Jan 7, 2007)

Jlarson said:


> I gather for some reason that you don't like just daisy chaining each e-stop. :laughing: I much prefer each one run back to the cabinet individually too. Gives you more options.


Takes troubleshooting time for a failed e-stop contact from 1 minute at the terminal strip to 1/2 hour opening up all the e-stops all over the whole machine or production line. Even a line only 50 feet long might have 2 dozen e-stops of various sorts.


----------



## Jlarson (Jun 28, 2009)

MDShunk said:


> Takes troubleshooting time for a failed e-stop contact from 1 minute at the terminal strip to 1/2 hour opening up all the e-stops all over the whole machine or production line. Even a line only 50 feet long might have 2 dozen e-stops of various sorts.


Yep I like less work, and terminal blocks are cheap.


----------



## LogicDB (Feb 12, 2010)

Right, thanks guys. There are no available terminals or space. I was scouting the conventions of this type of system (as per dwgs) to discover intent and options. Like I said before, they are lighted from outputs and offer inputs as well as the series hard wired loop (I don't have the option of home runs in this case). The estop that gets pressed blinks. I'm not designing, I'm the guy stuck with it. I wasn't sure about the core convention or intent of a 4 wire system. Obviously I have to go in on 1 and 3, out on 2 and 4, and so on. It seems stupid to me.


----------



## mattsilkwood (Sep 21, 2008)

MDShunk said:


> Takes troubleshooting time for a failed e-stop contact from 1 minute at the terminal strip to 1/2 hour opening up all the e-stops all over the whole machine or production line. Even a line only 50 feet long might have 2 dozen e-stops of various sorts.


 Amen. That will make you say bad words when you see 15 stations all covered in grease and they are all daisy chained through.


----------



## rahu_1989 (Oct 20, 2010)

I think, that for a safety relay we require 4 wires because we check the status of two contacts simaltaneously so as to declare a fault if the status of the two contacts has any discrepancy. If both the contacts (OF emergency switch )declares same condition then only we are assured that our emergency switch is working .


----------



## Introyble (Jul 10, 2010)

LogicDB said:


> I'm looking at a 4 wire e-stop. The drawings (that show the connections between controllers) are so bad that I can't tell the purpose of the 4 wires. Anyone wanna shed a little light for me?
> Thanks.


I see 4 wires constantly ~ 2 conductors on the n.c. (coming in after the stop latch) and a second set on n.o. contacts which usually disengage a solenoid valve.

Solenoid valves , of course, are a hazard since they can store potential mechanical energy. So disengaging the solenoid can be very important.


----------



## LogicDB (Feb 12, 2010)

These four wires were just a loop on the usual 2 wires (in series through the e-stops).

I think that the design was based on a plug and play paradigm (e-stop cable), and we installed it with pipe and wire.

I was inquiring early to seek intention, there were a lot of things on these stupid drawings that were hard to read one time through.


----------



## Bob Badger (Apr 19, 2009)

Logic have you read the thread, have you looked at the link?

4 wire e-stops and becoming the norm for redundancy and safety.


----------



## LogicDB (Feb 12, 2010)

Yes, Bob, I have.

Thank you very, very much.

I do understand, and for some strange reason this dead topic keeps taking off.

What I'm wondering is did you read that this is NOT what you think it is and that it is over, and figured out? This was a stupid drawing, a stupid system, and I was an installer on this system, not a designer. This was not a "saftey" circuit. It was some lab crap put together by a hack. 

Thanks again, seriously.


----------

