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.