Three Phase Emergency Stop Button

[BigSi]

Hi all.


I’m after a bit of advice regarding emergency stopping. I’m carrying out some remedial work on a building where it was noted that an hydraulic band saw had no form of emergency stop. The machine is started by it’s own start button, but relies on a stop leaver to activate when the cutting arm of the saw drops. If there was an accident, then the machine wouldn’t stop until you reached underneath and physically pressed the stop lever, or when the arm had fully dropped (a little too late then!).


I wanted to install a simple three phase latching (twist to release), emergency stop button to disconnect all three phases, but have trouble finding one. I didn’t want to install a DOL starter as there would be two start buttons for the machine (unless you left the DOL or band saw started on).


Any advice would be much appreciated.

 

[telectrix]

if the machine runs trough a contactor, just fit the EM in series with the coil.

 

[ImpededLoop]

Bear in mind that it may need to stop in less than 10 seconds as well. I'm not an expert on the requirements but someone else here should be able to help.

 

[BigSi]

That was one of my earlier options using a single phase stop button, but if there is a contactor (pretty old machine), is buried deep inside somewhere. All I have is the three phase isolator switch, and the conduit that runs straight into the machine.

 

[BigSi]

Bear in mind that it may need to stop in less than 10 seconds as well. I'm not an expert on the requirements but someone else here should be able to help.

I think it does stop within 10 seconds, but as the arm is hydraulic, I will keep dropping until it stops on the stop lever. I just need to stop the motor in case of an emergency.

 

[davesparks]

Before making any alteration to a machines control system you need to carry out the appropriate risk assessment to establish what is required to bring the whole machine up to current standards. Then you need to design the alterations to comply with the current machinery safety legislation.

You are obviously going to need one or more emergency stop buttons or other safety devices/interlocks added to this machine, plus a suitably rated contactor or relay

 

[Lucien Nunes]

If it relies on injection braking or any braking system that does not bring the machine to a safe condition with power failure, you won't be able to achieve compliance by cutting the supply as you will also cut off the braking. Your E-stop would have to be integrated with the machine's existing controls and this will require an understanding of the present risks and how your mods will affect them.

 

[BigSi]

Before making any alteration to a machines control system you need to carry out the appropriate risk assessment to establish what is required to bring the whole machine up to current standards. Then you need to design the alterations to comply with the current machinery safety legislation.

You are obviously going to need one or more emergency stop buttons or other safety devices/interlocks added to this machine, plus a suitably rated contactor or relay

Trouble is half the machine is hydraulic (industrial) so there would be no way to stop the arm from lowering. One emergency stop button should be sufficient as it can be located next to the machine and in easy reach. I know what you’re saying about interlocks, but I wouldn’t know where they would go or how they would operate. From what I was shown, they place a box section of steel in the machine, and it keep sawing till it stops.

 

[BigSi]

If it relies on injection braking or any braking system that does not bring the machine to a safe condition with power failure, you won't be able to achieve compliance by cutting the supply as you will also cut off the braking. Your E-stop would have to be integrated with the machine's existing controls and this will require an understanding of the present risks and how your mods will affect them.

I’m not sure if there is any breaking on it at all? It’s appears to be just a motor to drive the cutting belt.

 

[davesparks]

Trouble is half the machine is hydraulic (industrial) so there would be no way to stop the arm from lowering. One emergency stop button should be sufficient as it can be located next to the machine and in easy reach. I know what you’re saying about interlocks, but I wouldn’t know where they would go or how they would operate. From what I was shown, they place a box section of steel in the machine, and it keep sawing till it stops.

Then the emergency stopping system needs to work on the hydraulics aswell as the electrical controls.

 

[Darkwood]

You cannot always just add a simple circuit E-Stop Button say in series with the stop circuit, this will fall under the BS 60204 and the EU LV directive, if this saw is for joinery or similar then they have there own requirements dedicated to such controls like stopping times etc as already touched on...

Do not go into this blind as any future accident may lay heavily upon your shoulders as you will have to show you did a risk assessment and followed relevent regulations to boot and have a paper trail to boot.

Without indepth knowledge then critical safety systems are an area you should stay clear of unless your supervised or you have someone competent to sign it off on your behalf.

Because you intend to alter the existing control arrangment you will then become responsble to ensure the controls are brought up to standard not just on the E-stop but for any guard limits or access limits to say a belt housing etc etc...

 

[Lucien Nunes]

The hydraulics are often electrically controlled, e.g. on my Qualters if you cut the power it will stop lowering as the valve will close. But you need to verify the method of operation of the specific machine before deciding what alterations to make.

 

[BigSi]

Can I put a plug on it instead! :74:

 

[Pete999]

if the machine runs trough a contactor, just fit the EM in series with the coil.

What Tel said, simples as they say.

 

[rapparee]

You will also have to make sure when you release the e-stop the machine does not start up again.

 

[BigSi]

What Tel said, simples as they say.

I think I might follow this route, but will get somebody to check the machine who knows a bit more about it than I do. But I think at this time any emergency stop button is better than none.

Thanks for all the great advice as usual.:hurray:

 

[Darkwood]

I think I might follow this route, but will get somebody to check the machine who knows a bit more about it than I do. But I think at this time any emergency stop button is better than none.

Thanks for all the great advice as usual.:hurray:

I understand your thinking but I would strongly advise you get someone to look at it and advise you beforehand rather than the other way around. I fully understand your thinking about an E-Stop is better than none but unless you are taking the band saw out of use until it has been upgraded to regulation and inspected for compliance then either walk away or ask for supervision.

I see it all too often, this falls well outside of the BS7671 so only should be carried out by someone compliant with the appropriate standards...
The advice you are taking here may give you a functional solution but it may not be compliant or fail-safe and if anything did happen after your alterations then you would be fully liable and your insurance would be void unless you specify your involvement with machinery control and critical systems at the time you took your insurance out.

This is not the same as asking for advice about electrics within the BS7671 where you may have lack of experience in a certain area this is an area where you are probably not insured to carry the work out and is outside the scope of the BS7671 (guessing your not insured from the nature of your query).

 

[davesparks]

I think I might follow this route, but will get somebody to check the machine who knows a bit more about it than I do. But I think at this time any emergency stop button is better than none.

Thanks for all the great advice as usual.:hurray:

It's only going to be useful if there is someone there to push it quick enough!

Preventing the accident in the first place is far better than anything else

 

[snowhead]

I think I might follow this route, but will get somebody to check the machine who knows a bit more about it than I do. But I think at this time any emergency stop button is better than none.

Thanks for all the great advice as usual.:hurray:

No it's NOT.

By fitting it you are implying that if used the machine will come to an immediate and safe (as possible) stop.
You, or anyone else on here cannot say that without intimate knowledge of the machine.

Leave it alone till you or whoever is going to carry out the E.M stop installation are CERTAIN about what you are doing.

 

[netblindpaul]

Hi all.


I’m after a bit of advice regarding emergency stopping. I’m carrying out some remedial work on a building where it was noted that an hydraulic band saw had no form of emergency stop. The machine is started by it’s own start button, but relies on a stop leaver to activate when the cutting arm of the saw drops. If there was an accident, then the machine wouldn’t stop until you reached underneath and physically pressed the stop lever, or when the arm had fully dropped (a little too late then!).


I wanted to install a simple three phase latching (twist to release), emergency stop button to disconnect all three phases, but have trouble finding one. I didn’t want to install a DOL starter as there would be two start buttons for the machine (unless you left the DOL or band saw started on).


Any advice would be much appreciated.

Is this machine CE marked?