Contactor

[shieldssecurity]

Hi,

I need a bit of help wiring 3 contactors.

This is the situation.

I've got a pig feed system with 3 single phase motors each motor is to be triggered by a type of flow switch which has got NO and NC clean outputs.

My problem is the contactor which I have attached a picture.

I'm not entirely sure what goes where.

I think the moter is attached to T1 and T2 the feed is attached to L1 and L2

What I can't work out is where the flow switch is connected to and also where the red leads (as seen on the picture) go.

As you can see

A1 goes to 3

A2 goes to a connector on the side with nothing coming out of it

L3 goes nowhere

4 goes nowhere

I'ts probably really simple but I can't get my head arround it.

Can anyone help please.

 

[Sidewinder]

shields,

Wiring this up is not a problem, I would not be happy however with the method of actuation, iths may not comply with UK STATUTORY legislation.

Take A1 as your contactor coil live.

Take A2 as your contactor coil neutral.

Yes your motor L&N would go to L1 & L2, I would loop the L back from T1 to L3 and out of T3 to the motor

Take the motor N from T2.

The T references are on the overload (LRD08) NOT the contactor.

Set the LRD to motor FLC, unless you are expecting intermittent overloads that should be fine, else is it rating +20% I can't remember now!

That's the power side done, you OK with that?

We'll do control next if that is OK?

Got to dash of for a minute or 2.

 

[shieldssecurity]

I think I've got that bit......................I'll ask a few questions at the end if thats ok

 

[Sidewinder]

OK control,

Loop from your incoming L at L1 to your first emergency stop, from there to the next, the next the next etc.

From the last e-stop back to the 95 on the LRD from 96 on the LRD to one side of the start contact, from the other side of the start contact to A1.

Link A1 to 13 & A2 to 14.

This will give you a no volt release and a start from the switch and a stop from..........

No it wont!

You can't get a no volt release from that unit, you can't use it and comply with statutory legislation unless that rotary switch is momentary, is it?

Let me know & I'll carry on, it will however, still not comply with statutory legislation.

Off again for a mo.

 

[shieldssecurity]

No, the switch is not momentary its either "on" or "off"

I had a feeling this was not correct. The people who supplied the feed system opted for the contactors instead of the control equipment that the manufacture

 

[Sidewinder]

OK, the end user can't legally use it end of story as it will NOT comply with BS7671 (if that applies), BSEN60204-1 nor will it comply with PUWER98, thus probably not comply with EAWR89 also.

The end user will also probably fall foul of the management regs also.

You could fall foul of the CDM regs if you install it.

The start impulse must be momentary, i.e. a push button for example.

IF that switch were momentary you may get away with it but the configuration does not comply with statutory regs either!

 

[shieldssecurity]

Ok,

How about this.

What if they start the motor with the the switch on the contactor and the flow switch switches the system off??

 

[revjames]

Needs an EM stop

 

[shieldssecurity]

Theres an emergency stop unit fitted in the last feed bucket so if it gets over filled it shuts the motor off.

 

[Sidewinder]

Em stop must shut down all relevant devices, if motors are remote to the controls, then you really should have local lockable isolation adjacent.

An emergency stop is a manual device, not an overfill type switch, it can never be such.

IF you think about this, IF the pumped material can cause contamination oif the systems do not shut down then you may need to look at safety related parts of control systems, because the EA could get involved.

EM stops need to be located at relevant points within the system.

IF the system is controlling more than one motor or has more than 3 devices in the control system and 60204 applies then you cannot derive the control voltage directly from the mains supply (PUWER98/60204).

Your description in post #7 works from a functional stand point but it does not comply with legislation.

e.g. system is on and running, power cut, farm hand goes in to clean out the pump discharge as there is an issue, controller is on, pigs have eaten thus the switch is calling for feed, but it cannot work as the power is off.

Whilst the farm worker has his hand up the pump discharge the power comes back on, the control switch is on, the flow switch is on the pump starts and takes the farm workers arm off up to the elbow.

You wanna stand up against an expert witness and say you installed it correctly, regardless of the actions of the farm worker the control system would not comply.

The problem you have is even though the system may be installed in a building, 7671 is not really fully applicable, and it bows out to other standards, it is pretty close to the bottom of the pile really as far as safety standards go.

It is probable that the expert witness & the HSE specialist & their Wig would be carrying 60204, as well as 7671 & the PUWER98 ACOP, in which case both you & the farmer are stuffed!

Sorry!

 

[shieldssecurity]

This is why I love this forum.........................I'm just gonna tell them that if they want it done properly, they should buy the correct equipment.

Like you pointed out the stuff supplied would work but I'm not gonna be the mug who puts his name to it.

Thanks so much for all you help

 

[Sidewinder]

shields,

Tell them if they want a comptent designer then I can design it for them, I don't charge any more than my electrical rates! ; )

All the best.

 

[shieldssecurity]

I'll definately have a word with them tomorrow and get back to you.