Start stop switch

[dacosta]

Hi,

I currently have a rotary isolator feeding a start stop switch wich then goes on to feed a motor which drives a conveyor belt. The client has asked for an additional start stop unit unstalled close to the isolator. Is this possible if so how?

Many thanks

 

[telectrix]

if the location where he wants the start/stop is remote from the machinery, i would refuse.

 

[Kamikaze]

You can install another start/stop station for the motor but it would have to be wired in series.
i.e. the supply from the 1[SUP]st[/SUP] start/stop station will supply the 2[SUP]nd[/SUP] start/stop station which will then supply the motor. There usually is no point in doing this or are you just referring to a latching stop station?

 

[telectrix]

the stops would be series, but the starts would be parallel

 

[Des 56]

He may be able to bring a control cable back,a pair to series the stop button, and a core to parallel the start button,then use a standard start stop control switch,but the location may be unwise if its remote from the motor
Eaton / Control Automation - E22ASB204 - Interface Products - Automation & Control - Allied Electronics


edit
I see I lost that reply to tel by a good 8 minutes

 

[netblindpaul]

Any wiring would also HAVE to comply with the current version of BS EN 60204-1.
If you have 400V a.c. control, at all, or even 230V a.c. control without control circuit protective devices and not derived from a transformer then you cannot undertake the mods without the end user being non compliant with PUWER98 & yourself being non compliant with a host of other legislation.
It would also have to comply with a raft of other statutory requirements as BS 7671:2008 (including AMD1) is irrelevant in this situation.

 

[Kamikaze]

Tel and Des,
Sorry to slightly correct you guys, but you can’t connect the starts in parallel. Your not allowed to create a situation whereby someone hit’s the stop button on the one station and the motor can then be re-energized by hitting the start on the other station.
As netblindpaul has correctly indicated, there are a few hoops to jump through. Still can’t see the point in installing a second start/stop station unless the first one is too far away from the motor in which case it should be relocated.

 

[Ashley Williams]

If you connect starts in series you would need to press both starts at the same time for the contactor to energise. Starts are in parallel and stop in series.

here is a basic sketch of the simplest control circuit for a contactor. I would defently consider E-stop style buttons.



Uploaded with ImageShack.us

Ash

 

[dacosta]

Hi,

Thank you for the replies. Sounds like its not a common set up that the client is asking for. The belt is approximately 4 meters long with the start stop button at one end. There is a cut out switch linked in with this which when it kicks in means the worker has to sometimes walk to re energise. Both the buttons would be in view at all times. Dependant on where the delivery can fit is where the workers have to feed from. I am a fully qualified electrician but have only really touched on this kind of works in college.

Thanks again


Joe

 

[telectrix]

give the operator a pool cue if he can't be bothered to walk a few yards.

 

[netblindpaul]

dacosta,
If you are not familiar with BS EN 60204-1 then you should steer clear of this, as this would be the relevant standard NOT 7671.
Also there are other requirements under statute law also.

 

[dacosta]

I have looked into courses reating to this type of work several times with no luck. Work with control panels, contactors, relays emergency stops, inverters feeding various motors for industrial plant. This field is particular but i have the clientel base to make this time investment of sitting a course worthwile.

Thanks again

 

[Knobhead]

If the operator can be stationed at various points along the belt a method of stopping the belt should be within easy reach. Be it several stop P/B’s or a pull rope switch. If the operator has to walk a short distance to reset the system then so be it, four metres is hardly a marathon.

 

[telectrix]

agree with that. there's no problem with fitting extra stops as a matter of safety and easy reach, but there should never be any means of starting machinery remotely as that would be a major safety issue.

 

[spark 68]

Is it not possible to put the extra starts or all starts on a key switch ? (may be keyed different rather than keyed alike) on maybe a permit system ?

I agree with the stops being local though and I would personally prefer the PB E-stop type, as far as Iam aware you can have as many E-stops as required, and these should be in easy reach of the operator. I do have a BS document somewhere about E-stops.


Iam just asking this out of interest because I don't know

 

[netblindpaul]

agree with that. there's no problem with fitting extra stops as a matter of safety and easy reach, but there should never be any means of starting machinery remotely as that would be a major safety issue.

telectrix,
There are problems with adding more stops as you can fall foul off HSE guidance for compliance with PUWER98 depending on the original system.
In which case IF there is an electrical issue on the system, even though you have improved one aspect of safety you can reduce another and move the employer into a non compliance situation, and then get yourself into trouble for incompetent design not in accordance with statute law, ACoP's, CoP's & industry guidance.
Remember the LVD & the MD.

 

[telectrix]

agreed. i was thinking more on the lines of fitting e stop/s where they would be sited in the best interests of safety.

 

[Silly Sausage]

Paul

Out of interest, could you elaborate on the problems with having multiple stops.
I used to work on Chemical plants etc, (instrument work so no electrical stuff), so I always thought you could have as many STOP buttons as you liked. Invariably a local one and very often there were remote ones as well, seems to be a very sensible way of doing things.

 

[netblindpaul]

You can have as many as you like Archy, in fact the more the merrier.
However, if the control system is not in compliance with BS EN 60204-1 then you have issues.
I used to be acceptable to run 2 phases through a metal emergency stop button.
Thus when operated you had what is now a 400V a.c. potential across the button.
I very much doubt that you would ever come across this in a Petro/Chem environment.

 

[Silly Sausage]

You can have as many as you like Archy, in fact the more the merrier.
However, if the control system is not in compliance with BS EN 60204-1 then you have issues.
I used to be acceptable to run 2 phases through a metal emergency stop button.
Thus when operated you had what is now a 400V a.c. potential across the button.
I very much doubt that you would ever come across this in a Petro/Chem environment.

Mmmmm, I suspect I'm getting well out my depth here, but what the hell...

I almost had a whinge about BS ENs the other day but I deleted it, most people have no access/can't afford to buy them, I'll leave that one there.

In this case, the way I read it as...this is a 3 phase motor driven system, surely it can't take much thought, of which I'm not particularly capable of at the moment, to have any stop switches on anymore than 230v?

 

[netblindpaul]

Thing is you are not allowed to run control across 1ph & N either.

 

[spark 68]

Thing is you are not allowed to run control across 1ph & N either

Would you mind elaborating a bit further please Paul, as this is intersting stuff

 

[Silly Sausage]

Would you mind elaborating a bit further please Paul, as this is intersting stuff

If I can find them I'll dig out some of my old (2000) loop etc drawings and scan them if you want.

I seem to remember the interlock jobbies needed a bit of thinking about.
We only got -------eds once for missing something.

 

[spark 68]

If I can find them I'll dig out some of my old (2000) loop etc drawings and scan them if you want.

Please if you don't mind, I did some control and interlock wiring (with drawings), and Iam sure on that occasion it was all 24 Volt stuff, and mechanical interlocks (both cable and castell keys), I do have a BS document somewhere about E-stop circuits.
Thanks

 

[Silly Sausage]

Would you mind elaborating a bit further please Paul, as this is intersting stuff

It is.

If I had my time again I'd have left school and got in with an Instrument company/job.
Could have travelled the world by now, free and single, earned a wedge of of cash....

The past has gone, look forward to the future

 

[Silly Sausage]

Please if you don't mind, I did some control and interlock wiring (with drawings), and Iam sure on that occasion it was all 24 Volt stuff, and mechanical interlocks (both cable and castell keys), I do have a BS document somewhere about E-stop circuits.
Thanks

You might have to hassle me by email but if you want anything I'll see if I can find it.

 

[platty1005]

Hi dacosta this sounds like a 3 phase isolator feeding a 3 phase DOL direct on line motor starter with the stop start buttons on the front. The control circuit inside is probably 400V with NO overcurrent protection as the wiring is all inside the starter. Therefore it is not really safe to try and wire additional stop start buttons. If the (buttons) starter is in the wrong place it may be better to move the starter than try to wire extra stop start buttons.

 

[Knobhead]

We seem to be heading off at a tangent as usual. There is no mention from the OP of the control voltage!

 

[Kamikaze]

And I think he was more interested in starting the motor rather than stopping it. :smile5:

 

[netblindpaul]

We seem to be heading off at a tangent as usual. There is no mention from the OP of the control voltage!

Thing is Tony under current statute law machine modifications should be done to BS EN 60201-1, if the control system does not comply with this which is doubtful if it is an old machine, then, the control voltage is relevant to whether it is feasible to add additional control devices without the end user falling foul or PUWER98 legislation.
Additionally, would it really be a good idea to run unfused 400V control wires along a conveyor, now even if this was a CE marked machine if it is classed as a simple machine then unfused 400V control is acceptable under 60204-1.
If you add more control devices then it is no longer a simple machine etc.

 

[spark 68]

We seem to be heading off at a tangent as usual. There is no mention from the OP of the control voltage!​

And I think he was more interested in starting the motor rather than stopping it​

.

I thought we were discussing control gear both start and stop as well a E-stop, and remote/additional/slave controls, which was exactly what the OP was asking.

And if it is as tied up in so much legislation and rules, as NBP says it is, then is it not better to discuss this? , even if this is to stop someone from either, doing something illegal and or dangerous ?
or possibly help the OP with a way around his problem ?​

 

[Kamikaze]

Just a poor attempt of humour on a Sunday morning on my part. :redface:

 

[Engineer54]

I just don't know how all we older electricians and engineers have survived all these years, working with 415V/240V control circuits and coils... lol!! Though, i must admit, most of the stuff i was brought up on in my early days was transformer derived 110V and 24V. But there was plenty of the other stuff, on the bought in equipment etc!! lol!!

 

[Knobhead]

OAP elecricians please apply here :53:

 

[netblindpaul]

Tony,
There is no clicky! :whatchutalkingabout

 

[Knobhead]

Two in one day thats had me View attachment 7722

 

[platty1005]

Hi again Dacosta it is obvious the OP does not contain enough info so as usual we all make assumptions in giving feedback your OP basically says :-
" a rotary isolator into a stop/start into a motor operating a conveyor. "
Is it 3 phase or single phase ?
where is the contactor and overload that the stop start buttons operate ?
What is the control voltage for the stop start circuit ?
As I said earlier it appears to me to be a 3ph DOL set up not really designed to have the stop start circuit extended
Please post more info so we can give more relevant advice