Legalities of incorrect polarity upon purchase.

[wade88]

Hi guys,

Now, on two occasions now, a supplier of some of our machinery have supplied machines with incorrect polarity within the plug tails.... on today's instance, this obviously ran the motor in reverse, and has caused irreversible damage to the machine in question. I have now correctly wired the plug and double checked the internal terminations. The machinery they supply is built in China, its rough round the edges to say the least, and as far as i am aware, China do not follow any standardisation when it comes to wiring things, they just sling any old cable and colour in there.

But i find it utterly unacceptable that a machine supplier who fabricates and alters these machines to suit the clients end result needs, is sufficiently incompetent enough to wire the plug wrong and then deliver it "fit for key turn use" to a customer.

Today cost me time, blood and money after the machine almost fell to bits running in reverse, and i was wondering if there are any legal ramifications of sending machines out their dooor bought and paid for, that are in my opinion, potentially not safe.

Ben

 

[piccollo]

Dear Ben, had similar, I believe there is a general practice L1L2L3 N, but how many times do you find the wrong phase rotation on a incoming supply.
Just because the cores are correcetly connected, did they check for phase rotation. We know how to correct it, but as you say if the equipment is not marked or was tested else where, we don't find out until we try. piccollo

 

[44ALLAN]

My career average is 50% on going the wrong way when energising a 3phase motor for the 1st time
Quick on and off to check rotation before running it is the best way.
Good little tip for checking direction as well is to stick a tywrap into the cooling fan if you can't see it properly for rotation.........makes a great noise too just like the gizmo I used to put on the spokes of me bike when I was younger lol

 

[wade88]

Haha, thats brilliant, or get a piece of paper and see if it sucks it or blows it.... no innuendo intended.

Ok, well i wrote a pretty unimpressed email to them anyway, suggesting they get someone in who knows how to wire a plug before selling machinery to people, I just find it gobsmacking that their company "electricians" who are responsible for electrical integrity of their machinery before its sold or whilst its being built to begin with, are sufficiently ill equipped mentally to carry out the most basic electrical fitting job there is to the machine.

Cost me time and money today to sort that out after the domino effect of trouble it brought.

50/50 is a truly shocking percentage of incompetency or laziness.

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or am i just making too bigger deal out of this

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should i fetch my tiny violin

 

[44ALLAN]

Haha, thats brilliant, or get a piece of paper and see if it sucks it or blows it.... no innuendo intended.

Ok, well i wrote a pretty unimpressed email to them anyway, suggesting they get someone in who knows how to wire a plug before selling machinery to people, I just find it gobsmacking that their company "electricians" who are responsible for electrical integrity of their machinery before its sold or whilst its being built to begin with, are sufficiently ill equipped mentally to carry out the most basic electrical fitting job there is to the machine.

Cost me time and money today to sort that out after the domino effect of trouble it brought.

50/50 is a truly shocking percentage of incompetency or laziness.

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or am i just making too bigger deal out of this

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should i fetch my tiny violin

Look at it this way mate.......you could take your motor to 100 factories anywhere in the uk and plug it in to several different points in those factories and 50/50 would be a good result
Phase rotation and wiring in plugs/sockets/d/b's etc are all different.
Trick is to realise that and take all loads off a motor before powering it up for the first time........then quick on/off checking for rotation..........never run a machine full hog thinking it's automatically going to go the correct way..........won't happen believe me

ps
My record is actually 70/30...................................getting 30% right isn't too bad I thought lol

 

[wade88]

Ok, point noted, couldnt run this kit half ars ed anyway its on or off but it just wrapped itself around itself going backwards. However, today i learnt that more often than not expect the work of a numpty, take nothing for granted...not even correctly wired plugs. *sigh*

 

[gazzamikes]

Brave man starting it up! Sorry for asking but in what way could the motor not be disengaged from the drive train of the system?

 

[44ALLAN]

Ok, point noted, couldnt run this kit half ars ed anyway its on or off but it just wrapped itself around itself going backwards. However, today i learnt that more often than not expect the work of a numpty, take nothing for granted...not even correctly wired plugs. *sigh*

What happens Wade is that when someone finds a motor going the wrong way they may go to the isolator or D/B and change the connections in there on the main cables........this knocks everything out of sync and if this happens every time and all around the factory/site then it's anyone's guess which way it's going to turn regardless of how the plugs wired up.
Change the connections in the motor terminal box or the load side of the contactor then your main wiring is left alone........won't ever happen but it's a nice thought

Sorry if that post sounds patronising mate just read it back to myself.
Get work to buy you a phase rotation indicator for the next time

 

[wade88]

Oh well this piece of kit in particular was delivered with the incorrect wiring. DB's are all fine as did them myself (obviously they are ok..... :\ ) haha

It is run from an automatic run sequence that is written into the machine it is feeding's run program, so it plugs into the machine direct, then runs when the level sensor detects free space. So when it was plugged in and machine was energised, it just went straight into reverse before i had a chance to even scratch my ar s e.

No biggy now though, I am a wiser man for the tips.

 

[wade88]

Brave man starting it up! Sorry for asking but in what way could the motor not be disengaged from the drive train of the system?

Oh it could have been had i decided to check for correct polarity first and disengaged the motor prior to starting it up. Simply case of more haste less speed mate. Everyone on my back 24/7 here to have things working and machine down time to 0.1%, so i was clearly a little hasty turning it on, and also didnt expect the plug to have been wired backwards in the place.

Everyday is a school day

 

[gazzamikes]

I know the feeling! When I was working as a mechanical engineer every time a machine went down I was pushed to get it repaired and numerous times dropped things in the printing presses. Glad you've sorted it!

 

[wade88]

Well i've sorted the basic elements now the thing wont run in sync with the machine is feeding ( a volumetric form fill and seal machine) so, i am feeling decidedly beaten this week. Too many issues occurring that i simply don't have the knowledge to repair safely and effectively.

I have had to resort to outside help..... it's like asking the wife for directions. I need beer tonight, lots of it.

 

[44ALLAN]

Oh it could have been had i decided to check for correct polarity first and disengaged the motor prior to starting it up. Simply case of more haste less speed mate. Everyone on my back 24/7 here to have things working and machine down time to 0.1%, so i was clearly a little hasty turning it on, and also didnt expect the plug to have been wired backwards in the place.

Everyday is a school day

Amen to that mate still learning now and well into my 50's lol
Just out of curiosity...........how was the plug wired 'backwards'?
L1 to L3 or something like that?

 

[Knobhead]

The standard is L1, L2, L3 = clockwise rotation looking at the drive end. Works 50% of the time.
I had a contracts manager proudly tell me that the 100+ motors his lads had wired up would all go the correct way. I hadn’t the hart to tell him the 1KV incomers were reversed. He got it 100% wrong and I legged it when he came looking for me.

If you’ve got a drive that is liable to be damaged if it runs in reverse the simple answer is split the motor coupling or remove drive belts. You can’t blame the manufactures if you didn’t carry out this basic check.

 

[wade88]

Phases were just terminated into any terminal. No order.

Yea Tony i didnt make the check before hand correct.

But having said that I wouldnt expect to buy a kettle, and have it cool my water down instead of heat it up. Apparently in industry as you are all remind me, you don't necessarily get what you pay for, and when it is delivered to your doorstep, check it thoroughly first before assuming its correct/ and or works the way you expect it too.

I'm sure after i have been doing this for 20 years i will also be a fountain of enterprising knowledge.

This i have taken on board.

 

[gazzamikes]

The biggest problem I found was with German machines especially our presses they have the brown black grey but there's was black brown grey, always cases problems

 

[BlueToBits]

Could you not squeeze a phase monitoring relay into the control box? You can pick one up for less than £50.00

 

[44ALLAN]

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Wade.
What's happened here is something that has probably happened to every single spark who has wired up a 3 phase motor...........it's gone in reverse.
Checking the isolator/contactor/plug wiring etc will not make one jot of difference so no-one to blame there least of all you mate.

I learnt many years ago never to trust another sparks work so as a matter of course now I always open all panels and plugs etc and check/test the wiring before energising........whatever it is.
Good practice to get into that frame of mind mate and hope you don't think I'm having a pop.............not intended just trying to be helpful for future reference.

 

[ian.settle1]

When the machine was tested in China it may have gone the correct way but it comes down to the fact the motor should have been run without the load connected to check that the motor was going in the right direction before the load was applied or you should have started it and stopped it straight away just to check the direction before it got up to speed.

 

[wade88]

It's a bucket lift conveyor, its on, or off, no wind u speed, no alteration in speed, it just runs and stops. So i turned it on to run and it ran backwards, within those few seconds, its destroyed several parts on the machine. Hence the annoyance.

But at the time of the OP, i was unaware it is so common in industry to have a jumble of phases on gear so i shall endevour in the future to take nothing for granted and expect nothing to be consistent.