240v Control Curcuit

[Nazza]

Our company is working on a piece of machinery which has come from China.
We are ensuring the electrics are safe.

The control side of the electrics is 240v. All the components in the system are CE marked and from reputable brands.

1 electrician says we should remove all the control system and replace for 24v.

Another says the control system is fine at 240v as long as it is wired up correctly.

The machine is a fairly simple wrapping machine. Functions on the control curcuit include on of buttons etc.

We have been reading the machinery directive and the low voltage directive and all we can find is the phrase "it should be intrinsically safe"

So, my question is whether 240v in a control circuit could be considered safe and legal providing it is wired up correctly and the componenets are reputable brands with CE marks.

 

[LeeH]

I guess the stop and start buttons etc will only have 230v to them, these must energise a relay or suchlike which then connects the other phase for the 400v coil to pull in. With the relay situated in the panel. Thoughts?

View attachment 35489

 

[davesparks]

It sure will if there is a different phase connected to the A2, the control circuit is the same wether it is a 230v or 400v coil the only change is the connection to the A2 of the coil

It will be 240V to Earth, but it is not working to earth, it is working between phases and so it is 415V.
You don't install a machine which uses a 415V 2phase supply and call it a 240V supply.

If the cool is operating at 415V then the start contact will have 415V between its terminals when it is open, how on earth can that be 240V control?

 

[netblindpaul]

The OP has had the technically correct answers on the IET forum, but, has up until this point in time ignored them.

 

[davesparks]

Under the BS60402-1 the requirements state that if machinery(control system) has more than 2 actuators ie.. E-stops, limit switches etc then the control voltage must be of an isolated nature, this basically means that whatever the voltage may be it must be done through an isolating TX, where the control has less than 2 actuators then direct mains voltage control is fine hence you can buy a DOL starter with 400v, 230v coils wired directly to the supply of the installation.

What constitutes and actuator? Does this mean that a simple DOL starter with three buttons on it (start, stop, reverse or inch) would have 3 actuators?

 

[netblindpaul]

The OP has had the technically correct answers on the IET forum, but, has up until this point in time ignored them.

What constitutes and actuator? Does this mean that a simple DOL starter with three buttons on it (start, stop, reverse or inch) would have 3 actuators?

No, if they are in one enclosure then they are one "device".
Don't forget once you go from simple systems into safety devices, emergency stops, guard switches, light curtains etc. then you are into full blown EN 13849 territory and that is required for compliance with the SMSR & PUWER, and anyone doing this work is encompassed into this legislation.

 

[davesparks]

No, if they are in one enclosure then they are one "device".
Don't forget once you go from simple systems into safety devices, emergency stops, guard switches, light curtains etc. then you are into full blown EN 13849 territory and that is required for compliance with the SMSR & PUWER, and anyone doing this work is encompassed into this legislation.

Thanks, I'm only curious as to what point a simple system stops being simple.

 

[Lagentium]

Don't worry Pete, I don't need educating, I was just trying to grasp what the bloke said as I couldn't understand it.

 

[netblindpaul]

Thanks, I'm only curious as to what point a simple system stops being simple.

Once you have a safety function, so basically anything more than an e-stop, and more than the device count as specified in EN 60204-1.

 

[davesparks]

Once you have a safety function, so basically anything more than an e-stop, and more than the device count as specified in EN 60204-1.

Personally I just turn down any work which involves motor/machinery controls, but I do wish that at some point during my time at college someone had actually told us that these regulations even exist and told us what the average electrician can and cannot do without further training.

 

[LeeH]

Grab a copy of 60204 Dave, it's relatively an easy read compared to the BYB.

 

[davesparks]

Grab a copy of 60204 Dave, it's relatively an easy read compared to the BYB.

I was under the impression it was a tad expensive?

 

[LeeH]

It makes 7671 look a bargain.

PM sent.

 

[Bobster]

EN60204 is relitivly cheep, problem is going any deeper than the surface requires other standards like EN12100, E13849-1 & EN62061 being the main ones.

Looking at circa £550 for those 3 if you're not a BSI member.

 

[LeeH]

It's over 200 IIRC.

 

[Bobster]

60204 is £282 from BSi if you're not a member £141 if you are.