Emg stop circuit for ind kitchen

zombiekiller

howdy, i am required to put 3 emergency stop buttons in an industrial kitchen for all the sockets. In the kitchen there is a single phase circuit with 4 points, a single phase 16A socket and a 3 phase 16A socket. Can i use a 4 pole contactor with the 3 phase in the first 3 poles and the two single phase lives in the 4th pole. A 6A breaker feeding the emergency stops in series then into A1 of the contactor.Or am i totaly off the mark.

2011

You are not too far off the mark. Ensure that all devices are rated for the currents that they will be carrying and protected accordingly.


Here is how I would wire the power part:

3 Phase + N supply (all contacts are NO)

to

4 pole contactor (3 Phase +N)

to

Protective devices (3 Phase MCBs + RCD for 3 Phase sockets and RCBOs for single phase sockets)


Next the control:

Wire the E-Stops in series. These should energise an emergency stop relay. This will then be to provide a NO contact to the contactor coil. I will post a picture later, I have to go out now. Basically the idea is that the E-Stops latch and require a reset. We are being made change all E-Stops in work so that they latch, otherwise (technically) they are only stops.

zombiekiller

a picture would be brillant thanks. the way i drew it i had the the protective devices before the contactor but this sounds better. would they be better after as to break the supply quicker please explain

2011

OK, this was done in a bit of a rush but I think it is clear enough (God bless Tipex):



I am assuming that the first circuit is supplying 4 socket outlets.
The relay would be OK if it was rated for 40A per pole, but the 63A will last longer is switched under load. It will also have larger terminals.



Does this make sense?

As you can see contactor K1 is protected by a 40A MCB.
All MCBs are C type as this is normal for a commercial / industrial installation.

As stated above, the E-Stops will "latch", this is achieved by using an emergency stop relay (shown as ESR on the control drawing).
So if one of the E-Stops is activated the circuits fed from K1 will not simply switch back on once the E-Stops are all reset.
It will also be necessary to press the reset button. Increasingly this is becoming a requirement as many would only consider a latching E-Stop to meet the requirements of an E-Stop circuit.

zombiekiller

thanks very much thats great the relay aswel goog idea

2011

zombiekiller wrote: »

thanks very much thats great the relay aswel goog idea

No bother. I just corrected a few mistakes on the control drawing and used a pint of Tipex!
I have just redrawn and reposted, should be clear now.
Also added in an "optional extra" of status lights for the front of the panel.

mikemcdeedy100

yes


was it ever acceptable for emergency stops to re-energize the ccts when released?

-even with a key


not afaik

2011

mikemcdeedy100 wrote: »

yes


was it ever acceptable for emergency stops to re-energize the ccts when released?

-even with a key


not afaik

I am not sure to be honest. Like most people I have seen many emergency stops installed that do not latch. I think it is OK to do this if it is understood that they are simply "stops" and if an emergency stop is required it is wired separately and it latches. I am modifying a large MCC starter circuits to align with the required standards at the moment.

mikehammer67

ya i've seen it done in schools and the like where they just have key stops to turn off sockets

for the emergency stopping/switching however
the stops can't reset the circuit
-thats been the case since old 3rd edition rules anyhow

Bruthal

It also means in a power cut, machines won't restart when power returns.

It can also be achieved by wiring the emergency stops to the contactor the same as in a dol starter, with hold on contact etc, so the start button is actually the reset.