Class room emergency disconection

[ericmark]

Did use RBCO's on three phase they were an add-on kit and three units wide so we could just get 6 socket outlets on a 32 way board.

But as said before one has to be careful that an E-stop does not do reverse to intended and cause danger by allowing machines to run on. Same applies to any trip be it MCB or RCD eddy current breaking and ward leonard can produce problems and before any safety items are fitted a careful inspection is required.

Many years ago we had a workshop with all E-stops killing supply to all machines and some were placed to be knee operated and it was easy to trip in error. Losing drive to lath can break tool points and saws with lub pumps can jam solid. In our case normally only one guy working in the machine shop so not too much of a problem but with loads of people working in a machine shop I would be very wary.

 

[tonyelectric]

Yes Hager make add on kits to covert a TP MCB to RCBo, sensing coil fits onto output then an additional module sits beside the mcb and physically trips the toggle if a leakage is detected.

I'm quite sparing with wall stops and always at light switch height with a perspex flap, the individual stops on the machine only switch that machine, often the foor stop gets used as a way of stopping the machine so needs to be a rugged design. I often use bar stops on lathes that can be kicked anywhere along their length.

The driv-lock breaks will operate with the power totally cut but some designes require a maintained supply, hav'nt seen one for years though as they don't comply with 4163 that requires that in a power cut breaking should still happen within 10 secs.

 

[ELZ4742]

as do merlin. they clip on the back of the TP MCB to create a pod conversion.

 

[bernardgreen]

But as said before one has to be careful that an E-stop does not do reverse to intended and cause danger by allowing machines to run on. .

Or stop the machine so fast mechanical failure occurs.

I have seen the remains of a machine in which the coupling between motor and shaft sheered when the motor windings were shorted to dynamically brake the shaft. Then with no output from the motor in brake mode the control system assumed the shaft was almsot stationary and applied the mechanical brake fully to the shaft that was still running at full speed. The brake mechanism was torn away from its mounting and thrown across the factory floor. No injury as no one was in the path but there was a big dent in the casing of another machine. The resistors that should have been used to short out the motor windings for dynamic braking were not as specified and the initial dynamic breaking was too severe for the coupling.

 

[Buzx1313]

dont forget to use double pole mcbs for the 110v circuits if your protecting from the 110volt side of the tranny..

 

[ricicle]

dont forget to use double pole mcbs for the 110v circuits if your protecting from the 110volt side of the tranny..

Not necessary if you are earthing one side of the 110V output from the Tx (to create a 'Neutral') as per EN60204.....

 

[Spark123]

I'd imagine the 110v circuits will be for yellow ceeform type socket outlets for use with hand held tools. These should be fed from a centre tap earth system providing 55-0-55v, and as Buzx1313 says each circuit should be protected using DP breakers (or a protective device in each line.)

 

[ricicle]

I'd imagine the 110v circuits will be for yellow ceeform type socket outlets for use with hand held tools. These should be fed from a centre tap earth system providing 55-0-55v, and as Buzx1313 says each circuit should be protected using DP breakers (or a protective device in each line.)

Without reading through properly I'd 'assumed' the 110V was regarding the control circuit for the machines (which is why I refered to EN60204)