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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.
 
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.
 
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.
 
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.
 
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
 
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.
 
I thought you said in post #1 "the whole dis board must be de energised when the stop button is hit".
If that is the case you could run the feed to the board via a contactor, so the two sources would be in a separate enclosure.
 
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.

Safe isolation checks would prove to them there is still a live circuit.

I guess you don't do much with control panels?

Multiple feeds are common, and taking a feed of the live side is not unusual.

Does all of the workshop equipment supplied by this DB have no-volt release?
 
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.
Don't run the e/stop circuit through the DB then its not going to be problem is it?.

I've seen it done that way at repair workshops where an e/stop drops the supply to the DB which is feeding socket outlets on repair benches. The e stop supply was taken from the supply side of contactor.

Sent from my E5823 using Tapatalk
 
The equiptment hasnt been installed as of yet so no info. So you are saying i can come off the incoming side with fused protection to the em stops to control the contactor?

No not exactly - I'm talking about a device that attaches to say an MCCB (for example) as an accessory that acts as a tripping device when its control loop is opened (under voltage trip) - you would wire your N/C E-Stops to keep the unit energised and once the control loop is broken it would drop out the main MCCB. I maintain that this may not meet requirements depending on where your planning on using it - normally for schools you would bring all relevent circuits into a control board through a series of contactors or one main one with fusing down after, then use a safety relay to monitor the E-Stops and once activated it only kills the required circuits and not the whole board, resetting of the device also has to be discussed and normally should not be accessible for students to do so, so a key control is often used, this system is also favoured so the teacher can only energise it when he needs to so when absent the power is off to said outlets or loads, this stop students messing with machinery etc when no teacher is present.
 
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