E stop in a Circuit Breaker panel

[Cassie]

Hi,

We have 60A, 230V incoming to a din rail cabinet of breakers and control equipment. The input power is connected directly to a disconnect switch, then tied to a bus bar/mini circuit breaker system of about 30 breakers, some three phase, some one phase, ranging from 30A to 10A.

I'm needing to cut all power to the system with an estop, as there are moving parts attached to almost every breaker.

I've looked into adding anther three phase breaker before the disconnect switch, and adding a shunt breaker which will allow me to remotely trip this breaker (before it hits the disconnect switch). However, I've only found two options for this kind of setup: overvoltage trip, and undervoltage trip.

Undervoltage means that any time the machine is turned off, the breaker would trip. So, we would have to turn on the system, then open the breaker cabinet and switch on the breaker, every time. We have the system set up so that you have to close the cabinet before turning on the disconnect switch. This is backwards to our physical design.

Overvoltage means that we have to supply voltage to the breaker to trip it, so if there is a fault in the wire or the connection, the emergency stop wouldn't work. We want it to be fault proof (or as fault proof as we can get it).

Other than those two options, I'm stuck. I'm really inexperienced in this kind of thing, and was wondering if you had any other ideas on how we could install an estop in a system like this.

 

[MaxHeadRoom78]

I am not fully sure I understand, are you just wishing to set up a simple start and E-stop/system off circuit?
Normally this would be done with a suitable 3 phase contactor at the input right after the fused disconnect or main panel breaker with a N.O. P.B fed from a small auxiliary circuit.
I would assume you have some kind of system start/E-stop in place anyway?
Telemecanique wiring diagrams
Max.

 

[tomizett]

I'm not going to wade in as I don't know much about electrical installations either...
One thing that comes to mind, though, is whether you also need a "no-volt cutout" action: That's basically the action you describe in the 4th paragraph whereby the breaker will open if the external mains fails, preventing machinary from starting unexpectedly when the power is restored.

It took me a while to work out what you meant here:

So, we would have to turn on the system, then open the breaker cabinet and switch on the breaker, every time. We have the system set up so that you have to close the cabinet before turning on the disconnect switch

But is this an enclosure where all the controlls are hidden behind the door, and the door lock includes the actuator for the disconnector (like the one in this picture?). In that case, I can see why having to reset manually would be inconvenient.
Perhaps as Max suggests a self-latching contactor with an external "start" or "reset" button would suit you best.

 

[ClydeCrashKop]

This is a transfer switch for generators.
The micro switches are wired normally closed.
The relay puts 240 volts to the coil to switch contactor.
When contactor snaps, micro switches go open circuit.
Maybe you can make it work.
One of these controllers may help too.
http://www.deepseaplc.com/genset/auto-mains-utility-failure-control-modules/dse4520

 

[Cassie]

I am not fully sure I understand, are you just wishing to set up a simple start and E-stop/system off circuit?
Normally this would be done with a suitable 3 phase contactor at the input right after the fused disconnect or main panel breaker with a N.O. P.B fed from a small auxiliary circuit.
I would assume you have some kind of system start/E-stop in place anyway?
Telemecanique wiring diagrams
Max.

Thank you for your reply. Right now we have a circuit breaker system that looks like it should be installed in a home. To the main in switch, there are two e-stops connected. When the e-stops are pushed, a fourth breaker which is latched in with the main three phases is tripped, which causes the main three phase to trip also. However, we are completely redesigning the control system, integrating a more professional system, with the din rail mini breakers and disconnect switch.

I did a little research on the three phase contactor with push button operation, and I found a few things like this:

Is this what you were talking about? It's a simple and elegant solution. Thank you, I hadn't come across this. However, it looks like it's only going to work for one e-stop button. I was needing one at either end of the machine. If we wire two N.O. P.B. to the N.O. auxiliary circuit, in parallel, we would only achieve the stop by pushing both buttons.

Or, as far as I can see anyway. Like I said, I'm a definite green horn in this. Do you see a way I'm not seeing to hook up two estops with this or any other application you may have come across?

 

[Cassie]

I'm not going to wade in as I don't know much about electrical installations either...
One thing that comes to mind, though, is whether you also need a "no-volt cutout" action: That's basically the action you describe in the 4th paragraph whereby the breaker will open if the external mains fails, preventing machinary from starting unexpectedly when the power is restored.

It took me a while to work out what you meant here:

But is this an enclosure where all the controlls are hidden behind the door, and the door lock includes the actuator for the disconnector (like the one in this picture?). In that case, I can see why having to reset manually would be inconvenient.
Perhaps as Max suggests a self-latching contactor with an external "start" or "reset" button would suit you best.

Yes, I'm sorry. We've got a cabinet set up with all of the controls and breakers inside. We're using a panel mounted handle like the one in your reply to the disconnect switch, so that the cabinet is safely closed before power is engaged.

 

[Inquisitive]

If you use a NC E-Stop and wire it in series you can have E-stops on either end of the machine. Once the switch is punched it will open the circuit and stop the machine.

 

[MaxHeadRoom78]

Yes the E-stop string is all device,s AND'ed, i.e. in series, this can include any O.T. limit switches e-stop P.B.'s, or? etc .
The final device is the E-stop relay where a relay contact would also control the coil supply for any relevant contactors, another contact could advise, say, an operator panel that a E-Stop had occurred .
You can get E-stop P.B. that stays in when pushed with twist turn to reset, but I prefer the momentary P.B. with the system start P.B. there are a few examples in the Telemecanique wiring examples.
To take it further you could look into Safety Relays, they come in different configurations, for e.g. time delys included for staggered shut down etc, these are slowly becoming mandatory in N.A., they have been in use for some years in Europe.
Max.

 

[KeepItSimpleStupid]

Do some research on "Safety relays". That's really the device that should tie all of the e-stops together.

 

[dr pepper]

If I was going to do something like that I'd use the required (in the uk) safety contactor connected to the e-stop, such as a pilz pnoz3 and a safety contactor inline with the incoming 415, and connect the feedback contacts of the contactor to the pnoz so it can monitor the contactor.

If you want something to trip all the breakers at once you can do that, there are magnetically released 'breakers, these are however highly specialized, I've never used them.