Contactor controlled distribution board via emergency stop

[Chris Morris]

Hi. Im looking for the best advice for wiring an emergency stop circuit controlling a dis board via a contactor. This is a dis board feeding circuits in a workshop so the whole dis board must be de energised when the stop button is hit. The problem being the contactor is fed from the dis board in question. Any info would be great thanks.

 

[Darkwood]

It would depend who is using the system and the safety level requirement, this you need to know to you design this, when its implemented to possible save lives or injury then there are many requirement beyond just making a functional E-Stop circuit to drop out a Dist' board.

 

[Perryway-]

Is the Dis board at the origin or is it remote to the supply ie fed in armoured etc?, if the dis board is at the origin can you not install an isolator for em stop circuit then you dont have to worry about the contactor being fed from the dis board when the stop buttons are pressed as the em circuit will be isolated from separately.

 

[Chris Morris]

It was more along the lines of regarding the em circuit you cant come off the load side and you cant come off the mains side as it would be bad practice even with an inline fuse etc.

 

[Darkwood]

Fit a main switch with the ability to have a trip unit attached, most main MCCB allow for this but on its own it won't meet the requirements for workshop isolation in schools and colleges etc like I say there is a lot of regulation around this although if your doing this for your own personal use then how you achieve a functioning system is your choice.

 

[Perryway-]

Where is the dis board in regards to origin of supply, why would it be bad practice to have the emergency stop circuit seperate to the dis-board this way the board will still be isolated and youd have isolation for the em circuit

 

[netblindpaul]

As DW says, why are you doing it?
There is only on scenario where such a system is required, and then it is much more complex then dropping out a DB.
This is not as simple as it may seem, and there is no statute law requirement for such a system, so you must be sure of the design specifications and requirements.
If you are designing the system, then you need to be sure of your clients functional specification and then design to meet this in compliance with the statute law requirements.

 

[HandySparks]

...you cant come off the load side and you cant come off the mains side as it would be bad practice even with an inline fuse etc.

Sure, it needs fusing down, but why would it be bad practice?

 

[Adam W]

Why can't you take a feed from elsewhere?

 

[Chris Morris]

Because when you kill the board via the main switch there is still a live circuit.somebody working on the circuit at a later date may not realise this.