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.



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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?