24v relay circuit - elp!

[wade88]

That was the O/L that i was told by RS i MUST purchase for this DOL. I was even prompted by RS to ensure i had got the O/L ordered alongside it.

This entire thing has turned into a total box of frogs.

 

[wade88]

I want to lie down and not get up again.... preferably in Antigua or something

 

[wade88]

 

[wade88]

Buy DOL & Star Delta Starters ENCL.+CIRC.BREAKER, LG8K06Q707 Telemecanique LG8K06Q707 online from RS for next day delivery. this would be a lot more appropriate for what i have wouldnt it.

That DOL on my desk is way too big, and like you have rightly pointed out the O/L is well off.

This motor is only running at 1.2 amps or thereabouts.

Balls.

Looks like its a re-order at RS then

- - - Updated - - -

Got EM stop built in too

 

[SheffSimon]

Buy DOL & Star Delta Starters ENCL.+CIRC.BREAKER, LG8K06Q707 Telemecanique LG8K06Q707 online from RS for next day delivery. this would be a lot more appropriate for what i have wouldnt it.

That DOL on my desk is way too big, and like you have rightly pointed out the O/L is well off.

This motor is only running at 1.2 amps or thereabouts.

Balls.

Looks like its a re-order at RS then

- - - Updated - - -

Got EM stop built in too

Just buy Buy Contactor & Control Relay Overloads Thermal overloadrelay,1.2-1.8A FLC range Telemecanique LR2K0307 online from RS for next day delivery. and set it to the full load current of the motor, not its normal running current. Should be 1.6A for your motor...

As for the e.stop, re-read whats been said earlier in this thread. You need to assess whether the e.stop circuit in this box is adequate and correct for YOUR application/risks and YOUR requirements, and that involves a bit more than sticking a red button in a box with a yellow ring round it.....

 

[wade88]

Ok, i personally don't feel an E stop is essential, as the hopper will be mesh guarded and there is no way am operator could get any body part into the screw feed anyway, i just assumed from what i had read it was law to have one.

I need to check up on the legal requirements of such things this afternoon, but that was the impression i have gotten.

I am having all this gear sent back today anyway and will re-purchase more relevant equipment.

I need to start this whole process again on a clean sheet.

 

[Knobhead]

 

[plugsandsparks]

Struggling to understand why, with such a major modification to this machine that the manufacturer or whoever is the machine designer has not provided the necessary documented electrical , mechanical and safety systems. Its been law for quite a while so would expect machine builders to be used to it by now.
Sure its no sweat to get a machine to start and stop / reverse under push button and plc command but that is about 10% of what has to be covered.
Dont really understand the human risk of injury on this type of plant so not going to try and add anything meaningful but just perplexed as to why its down to the site electrician to "come up with something that works"
BTW - i do find it hard to believe its not possible to get injured by this machine.

 

[Spoon]

BTW - i do find it hard to believe its not possible to get injured by this machine.

It is possible. If you read post 51 "as the hopper will be mesh guarded and there is no way an operator could get any body part into the screw feed".
Other industries use mesh guards for mixers, so you just dump your mix through the mesh and the operator can't get to any moving parts, therefore removing possible injury.

 

[wade88]

It shouldn't be my job to do this no. It's been a point of contention since i first received the email because 1) it just shouldn't be down to me to do such things after we have paid out over £250k for the whole system, and all aspects of the process should be covered 2) clearly i don't have the knowledge to carry out such work making it dangerous.

This is why i have written back and said i will not be making any modifications myself until a colleague of mine from another firm with 15 years more experience is on site to assist me.

So, it's not so much a problem anymore. I was panicked to begin with as i was being pressured by just about every bugger going to get it working and find a solution in under 72 hours and frankly didn't know what i was doing but as has been highlighted, its just not worth the jail time or potential injury for the sake of getting "the job done".

I understand my limitations and won't be prepared to the cross the border into dangerous working practices. I'm borderline enough as it is lol

 

[wade88]

 

[plugsandsparks]

OK, understand, might be worth getting the plc programme off for the relevant output that you want to stop or inhibit the starter. Just to make sure its simply an inhibit and not something else as well. Also you will need to know what output it is on
What happens if the plc inhibit fails to inhibit, is it just a messy pile or will the doors blow off... )

 

[wade88]

Wouldnt make a difference if the PLC programme failed anyway. The PLC involvement in this process in my opinion is totally redundant. It has complicated this entire issue.

Basically the auger will be manually loaded with a known amount of dry materials, (biscuit mix) by an operator. When he has loaded the exact amount in, the load cells should register the correct weight and turn the auger off. Why we need this process to be automatic is beyond me, whats wrong with just pressing stop?!

So even if the PLC fails to inhibit the aguer, the screw feed will just keep turning without any material in it. So its a total waste of time to be honest. But their engineers who have designed the machine and written the PLC sequences believe its important and beneficial to have this automatic PLC involvement.

I however, am not at all convinced. Trying to remove the human element and replace it with a PLC is just asking for trouble.

 

[Spoon]

Im feeling like Whinnie-the-Pooh this morning "a bear of very little brain" so am I right in that the idea of this project is that:
Someone loads the auger with a known amount of mix, then the operator manually start the auger. The auger moves the mix up and into the ribbon mixer. The ribbon mixer has load cells on it and when they register the correct weight then the auger stops feeding the mix. (using a PLC signal). Is that how its meant to work?

 

[Knobhead]

It is possible. If you read post 51 "as the hopper will be mesh guarded and there is no way an operator could get any body part into the screw feed".
Other industries use mesh guards for mixers, so you just dump your mix through the mesh and the operator can't get to any moving parts, therefore removing possible injury.

I spent 25 Years in quarrying, mesh gaurds are no barrier to a plant opperator. One guys head was crushed by the bar he was poking through a mesh gaurd. It doesn't need to be a body part.