Contactor chatter and burn out?

[Knobhead]

Paul, I thought you were going to let OJ know the relevant BS standards so he could use them in his argument against this unsafe system.

 

[netblindpaul]

Forgot that!
Sorry.

BS4163, latest is 2007, there was 1984, then 2000 prior to this.
Title:
"Health and safety for design and technology in schools and similar establishments - Code of practice"

My point to note is the last part of the title "Code of practice"!

This is the next level down in the document tree to an ACoP.
It will carry more weight than even BS7671, which is not recognised as a CoP.

 

[Knobhead]

Cheers Paul

 

[ojchurch]

Brilliant I will look into that on Monday. Cheers.
In terms of making sure the circuit doesn't re-energise when you unlock the stop switch what system do you use? The only school I've done before we used a proprietary system called Gas Guard. This was supplied separately from the local circuits & operated a contactor fed local DB to kill those circuits.

 

[Knobhead]

This should do for what you need

View attachment 12108

 

[johnboy6083]

Ive just done a drawing for you, but cant convert iot from dwg, to a jpeg, so you can see it on here!

 

[johnboy6083]

tony beat me to it.

 

[ojchurch]

Many thanks again for your advice/time.
It seemed fairly obvious to me the dangers of no monitoring on a safety switching system. I had to explain the possible dangers before any of the site management took any notice. Now I have the evidence to force them to alter the affected areas.
Thanks again.

 

[johnboy6083]

if your looking for a premade system, then a basic DOL starter will do the job. It must though: a) it needs to be rated to switch the contactor to the DB, or b) it needs to be able to switch the DB feeding all of the machines that you want protecting by the e-stop circuit.

 

[netblindpaul]

What the central switching system is, is basically a DOL starter, with several stops and one start.
I strongly recommend using key release emergency stops.
The "On" button should also be key controlled, I always do, IIRC this is in 4163.
However, it also must be momentary, think of the ignition switch on a car, for the cranking position, when released it springs back.
I know Tele (Schneider) do one as those are what I use.