# Multiple start buttons on a machine.



## tmerc65 (Jun 10, 2009)

Using NFPA 79 as a guide I get
9.2.5.2.4 – If more than 1 start device is present then all start control devices shall be actuated concurrently.
9.2.7.5 – If there is more then 1 control station then only one station can be active at a time.
The reasons:
The operator would like multiple start and stop buttons on a machine that needs to be threaded in the beginning of the process. As he walked along threading the machine he would always have a place within reach to stop and start the machine as needed.
My way around the above standard would be to place the machine in a THREAD MODE that would only allow the machine to run at a slow speed (less then 250mm/sec) and the buttons that would not be labeled start but THREAD SPEED would only be active in this mode and do nothing when the machine is in RUN mode. Of course the STOP buttons would still work.
Am I on the right track.


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## MDShunk (Jan 7, 2007)

Machine too big for a pendant control on a reelie or swinging jib? Just a thought.

EDIT... I seem to recall an exception for multiple start stations if there's a warning bell and lights thing for a certain number of seconds before it starts .


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## hurk27 (Jun 2, 2009)

Why use start/stop, a few jog button's should do the trick and it will stop as it is released? preventing injury, A placed where I worked made fiber that also had to be threaded through the different sections of the line, and after a Hand/Auto selector, was several Jog buttons placed where needed. in auto the speed servo system took over but in jog it would inch the fabric along slowly to give you time and make it safe to feed the fiber through. oh and yes we did have bells and strobs any time it was starting.

But without knowing the Sequence of Operation its just a guess?


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## tmerc65 (Jun 10, 2009)

1) The machine has 2 levels. Now why climbing a ladder while holding the web isn’t a bigger safety issue is not my concern at this moment.
2) I like the delay idea, Hold the thread button for 2 seconds while an alarm sounds if you release the button before the 2 seconds the machine does not start. I can’t find that in NFPA 79 but maybe it is in another publication 70E or OSHA I’ll start digging.


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## tmerc65 (Jun 10, 2009)

hurk27 said:


> Why use start/stop, a few jog button's should do the trick and it will stop as it is released? preventing injury, A placed where I worked made fiber that also had to be threaded through the different sections of the line, and after a Hand/Auto selector, was several Jog buttons placed where needed. in auto the speed servo system took over but in jog it would inch the fabric along slowly to give you time and make it safe to feed the fiber through. oh and yes we did have bells and strobs any time it was starting.
> 
> But without knowing the Sequence of Operation its just a guess?


This is a wire coating machine and sometimes the wire is thick and needs two hands to thread so push to hold Jog doesn’t seem feasible. I wouldn’t want one operator doing the threading while another holds the button.


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## drsparky (Nov 13, 2008)

Put in a PLC and software any change you want.


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## tmerc65 (Jun 10, 2009)

How to do this is the easy part.
My problem is if I design or make a change to an existing machine I then have to perform a safety audit. So I have to explain why I did the change in the way that I did. I usually (can’t always) try to support my why’s with a Code, regulation or safety standard to support the change. This audit then becomes part of the machine literature.


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## GSH (Sep 24, 2009)

Did you get this figured out?


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## hurk27 (Jun 2, 2009)

tmerc65 said:


> This is a wire coating machine and sometimes the wire is thick and needs two hands to thread so push to hold Jog doesn’t seem feasible. I wouldn’t want one operator doing the threading while another holds the button.


And you think having a timer is better?:blink:

I can yell at a person to stop, can't yell at a timer


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## AussieApprentice (Aug 16, 2008)

tmerc65 said:


> Using NFPA 79 as a guide I get
> 9.2.5.2.4 – If more than 1 start device is present then all start control devices shall be actuated concurrently.
> 9.2.7.5 – If there is more then 1 control station then only one station can be active at a time.
> The reasons:
> ...


I am not familiar with your code but I would not think that what you propose would be appropriate. I believe that what you want to do is ensure that person threading the machine has sole control. 

If he is at Station 1, he could pass control to Station 2 and move to that position. From there he could pass control to Station 3 and so on. He may want to have the option to pass control back to Station 1 without completing the sequence but that would depend on the the safety of the particular application.

Another way to approach it may be to switch to threading mode and no stations become active until some kind of switch indicates that someone is at a station and locks out the other stations.

If 2 handed operation is required then there are options such as foot, hip, elbow switches and cables to act as stops and safeties.

You will have to decide the best way to give the operator sole control.


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## GSH (Sep 24, 2009)

I was thinking along the same lines as AussieApprentice. You could put a switch (foot switch would probably work) at each station that would only activate that particular station when the operator was there.


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## Amish Electrician (Jan 2, 2010)

IMO, the NFPA needs to stay out of control panels. 

Having multiple start/stop stations is no problem. In such an arrangement, the customary way is to have all the 'start' buttons in parallel, while the 'stop' buttons are in series. Also, the 'stop' buttons need to be deliberately reset, rather than held in, or the machine won't start.

This arrangement is quite common with conveyors.


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