3ph DOL star/delta (auto changeover)

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Hi guys.

Just been to look at a job on the starter to a large compressor.

It "wouldn`t start"!! Likely to be the starter then! :B

So went and freed the stuck contactor, and off it goes. HOWEVER.......

We`ve got 6 motor wires - all red - unmarked. 3 of them are not connected to the contactor - appears to have a contactor pole fault (delta).

The "start" button doesn`t -switch the local isolator on, contactor 1 fires, then 2 & 3 after a short delay.

I understand the process involved, and the general wiring proceedure. My question is:

If they want to to repair/replace the starter (which they do),

1...Who makes the best/most cost effective solution?

2... The three motor wires which are disconnected. How can I determine which is which? Or, if my thinking is correct, does it matter, as, from rusty knowledge, they all get shorted together when the delta contactor fires.

DOL box contains: 3 3ph contactors. 1 electronic time delay. 6 motor winding wires (u,v,w,u2,v2,w2 I think???) 4 control wires from compressor. 3 phases supplied (no neutral).

Strangely, I didn`t see an overload in there. However there is a small "radial lead" component - varistor or something maybe? Think it may be to do with the time delay. It`s connected between motor contactor L3, and star contactor L1 (at least, that`s where, from memory, i THINK it was!)

Cheers guys. The 3 ph side of it isn`t a problem; I`ve never had dealings with an auto-changeover before. Plus these un-connected motor wires are spooking me a little, in case I`m wrong about the correct connections.

KME

 

steptoe

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possible it could be a dual motor,

ie,

either *D

or

DOL

Im not really sure if you can mix the 2

I never have, thats for sure.

maybe thats the extra wires, but why did the original starter pack up tho?

 
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Think its just old m8.

I`ve been gleaning info, and, from what I`m told, they had a guy look at it some 7 or 8 years ago, when the compressor wouldn`t work. He diagnosed fault on one pole of the motor contactor (I agree), and, because the owners were tighter than a duck`s bum, they said fix it without buying a new contactor.

New owner since, and now that its playing up, he wants it sorted! It supplies ALL the air for the garage, workshops & bodywork & spray booths.

It seems that the original sparx`s fix was to remove the delta option, and "borrow" the delta starter for driving the compressor. So, at the moment, it doesn`t change state.

Primarily, I want to confirm that the "unused" 3 wires should be shorted through the contactor, after the motor is at running speed. "Johnny 5 need INPUT!"

 

steptoe

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FFS,

OK,

Im a long way away.

lets keep it that way.

hate them jobs where someone a few years ago sorted it out for us without spending money, cant you do the same.

dunno TBH buddy, am kinda lost without being there, not that that might make any difference anyhow.! ?:|

sorry.

 
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OK, on re reading your post,

this is using a DOL to start a STAR,

but its actually starting it on the DELTA winding?

is that correct?
NO mate.

It appears they removed the delta wiring, and " borrowed the contactor for the star windings, cos 1 pole of the star contactor is u/s.

So......They took the delta windings away, and connected the star wiring (properly), to the (what used to be) delta contactor.

Do you want me to take a photo for you mate?

Looks like an explosion in a spaghetti factory inside that box mate.

I took the cover off, and said a four letter word that means poo.

little red wires, going everywhere; nowhere, and all things inbetween.

AND THEY`RE ALL UNMARKED, AND ALL THE SAME COLOUR:_| :_| :_|

Then I just stood and traced things for a few mins. And here we are!! :eek:

 
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Well bud...

I'd like to help on this one.....

But I'm out!

I'd have to go trawlin back though too many books and notes to get me head back round those 3-phase motors & starters.

Any way I'm still strugglin with me 7core trailer lights cable...

Left indicator..

Right indicator..

Brake light..

Earth..

erm..

erm..

No its gone again! :( :(

Left indicator.. Right indicator.. ? ? ?

:( :p :p:p:p:p:p;\ :eek: :_|:8}:8}

Now if you wanted to wright a stinking letter to the bloke..

tellin him your going to take out a personal injury claim against him.

for having too many confusing wires on his installation..

and its given you a head ache...

Then I reckon we could knock something up quite quick!!! :D :D:D:^O:^O:x

 

sparkyrj

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Hi, it looks as though you have a star delta starter here, not a DOL. These do have three contactors and a time delay relay in them. Should just need replacing with new one with correct size overload fitted.The three other wires will need to be connected though.

 
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Hi, it looks as though you have a star delta starter here, not a DOL. These do have three contactors and a time delay relay in them. Should just need replacing with new one with correct size overload fitted.The three other wires will need to be connected though.
Yup. My mistake, using the direct-on-line term.

The main queries are:

1. Do I just change the 1 contactor that has a duff pole? Or that one PLUS the one that got jammed. OR replace the whole flippin` thing?

2. The "other" 3 motor wires - I THINK?? they are shorted across the third contactor. Am I right?

 
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Well bud...I'd like to help on this one.....

But I'm out!

I'd have to go trawlin back though too many books and notes to get me head back round those 3-phase motors & starters.

Any way I'm still strugglin with me 7core trailer lights cable...

Left indicator..

Right indicator..

Brake light..

Earth..

erm..

erm..

No its gone again! :( :(

Left indicator.. Right indicator.. ? ? ?

:( :p :p:p:p:p:p;\ :eek: :_|:8}:8}

Now if you wanted to wright a stinking letter to the bloke..

tellin him your going to take out a personal injury claim against him.

for having too many confusing wires on his installation..

and its given you a head ache...

Then I reckon we could knock something up quite quick!!! :D :D:D:^O:^O:x
You fool! You dom`t use 7 core for trailer lights anymore.

Use two core, with addressable lights. Welcome to digital age!

And as for the "stinking letter" idea - If I was going to do so, you`d be the first person I`d want to liase with!!! :x

 
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You fool! You don`t use 7 core for trailer lights anymore.Use two core, with addressable lights. Welcome to digital age!

And as for the "stinking letter" idea - If I was going to do so, you`d be the first person I`d want to liase with!!! :x
My poor trailer has never worn aDRESS in its life.... :eek:

and it ain't gonna start now! X(

I don't have no woosie Sheila trailer!!! :(

tis a proper full metal blokey job! X( :|

Anyway I got a bit of 3core SWA & 4core SWA off-cuts...

reckon that I'd be good un safe to get 7cores for the ole' trailer connections?

:D ] :) :p :p:p:p:^O:^O:^O:^O

;)

 

steptoe

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NO mate.It appears they removed the delta wiring, and " borrowed the contactor for the star windings, cos 1 pole of the star contactor is u/s.

So......They took the delta windings away, and connected the star wiring (properly), to the (what used to be) delta contactor.

Do you want me to take a photo for you mate?

Looks like an explosion in a spaghetti factory inside that box mate.

I took the cover off, and said a four letter word that means poo.

little red wires, going everywhere; nowhere, and all things inbetween.

AND THEY`RE ALL UNMARKED, AND ALL THE SAME COLOUR:_| :_| :_|

Then I just stood and traced things for a few mins. And here we are!! :eek:
NO I dont,

go away and annoy sparkyrj instead.! ]:)

he's obviously telephatic and has got his head round this without even seeing it,!!!

bloody smart ****. :_|

 

sparkyrj

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If it is a stardelta starter that you have, then it may be possible to replace the internals if you can get an exact replacement, otherwise its the whole thing.there are wiring diagrams on the johnson controls website, and also on google images.The other three cables do need to be connected. Hope this helps.

 
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If it is a stardelta starter that you have, then it may be possible to replace the internals if you can get an exact replacement, otherwise its the whole thing.there are wiring diagrams on the johnson controls website, and also on google images.The other three cables do need to be connected. Hope this helps.
Indeed it does. Thanks m8. I`ve sussed the wiring, and am going to replace all 3 contactors, and fit an on (and off) pushbutton to the existing casing.

This is all if they accept the estimate!!!! ?:| ? :| ;) :eek: :^O

 

davetheglitz

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Be very carefu;l with the compressor starter - they often want the pressure switch to maintain pressure in the tank rather than just acting as an overpressure device to switch it off. This makes them a bit different to a conventional star delta starter - and you may need an additional switch or a couple of relays to sort out the logic!

 
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