Compressor 3-Phase wiring

[normspanners]

IMO that full box picture bares no resemblance to either of the diagrams
where are the speed controllers for one? the wires to either contactor are in the wrong places and where are the chokes/ reactors ?

 

[normspanners]

Need some more digging from the op.

Definitely Chris --------- I would not like to be quoted on where to stick 415 into that ! and those diagrams are for something else IMO
I think it maybe had speed control at some point but looks now to be DOL... to me.

 

[normspanners]

We have only half the info and half of that info is wrong. / and needing more pictures IMO

 

[daleyd]

We have only half the info and half of that info is wrong. / and needing more pictures IMO

Yep I’d agree with that - I initially suggested going through the supplied drawing line by line and ticking stuff off but realistically looking at it again you’ll probably be best drawing it out from scratch.

 

[knighty]

6 wires coming from the motor, so you can wire in star delta if you want.... but it's wired directly into star

that's pretty standard practice for a lot of stuff

 

[daleyd]

6 wires coming from the motor, so you can wire in star delta if you want.... but it's wired directly into star

that's pretty standard practice for a lot of stuff

Not something I’ve ever seen, unless it’s been changed around at some point, ie it was star/delta previously and they’ve just left the wires in back to the terminals.

Most motors will have terminals on the motor and the links/connections for the various configurations in there. That’s not to say it couldn’t be done like this, just that it wouldn’t be that common in my experience.

Whatever - it would certainly be a good idea to sketch out what is actually there and in what configuration.

 

[Gary900r]

Best guess would be that it had a VSD and electronic controler one or both have blown and some one has converted to dol and mechanical switch. Can you post a pic of complete machine

 

[normspanners]

6 wires coming from the motor, so you can wire in star delta if you want.... but it's wired directly into star

how can it be wired star delta start with only 3 terminals to connect 6 wires to ?
we need to see the motor plate to see what the motor actually is, just because it WAS running wired the way it is doesnt make it right, some motors can be damage running them incorrectly, long term, also with it having a speed controller the motor could possible have been wired so that a smaller frame motor runs faster and more powerfully than it would normally do, using VFD you can get the motor up to 80/90 ish hz using a 4pole motor at 2800ish rpm which is happily close to twice its design rating, but starting it dol long term could fry it?
There must be a reason it has speed control written into the diagram how would the speed controller know the air requirements for instance ? not from that pictured pressure switch IMO, it could be it was designed for a limited supply situation that ramped up the motor slowly because compressors are not kind when it comes to current inrush on a smaller capacity supply but will run happily once up there and pumping.

 

[WorkshopChris]

Personally i would say at the moment with the information we have there are to many variables and unknowns to power up safely at this point.
EDIT some hydrovanes use different speed motors for different output pressures.

 

[knighty]

how can it be wired star delta start with only 3 terminals to connect 6 wires to ?

there's 6 wires coming from the 6 terminals in the motor, so the motor could be wired in star delta with a different control box or an extra couple of contactors in that control box - I've seen the same thing before, they have motors on the shelf ready to use with 6 wires, then they wire them in as needed, when they need them.



wiring looks pretty bog standard for a compressor to me

I think those wiring diagrams are either wrong or for a different compressor, they show a programmable controller and lots of options that aren't their in tona955 's control panel (or maybe the same diagrams cover a lot of different compressors with a lot of different options)

tona955 - if you want to trace where the other wires go and post pictures I'll be happy to whip up a quick diagram for you - or just look and see where the extra wires go to and it should be pretty obvious what they're for

the only wire I'm not sure about is the black flex coming in from the right, it goes to a connector block and then 3 red wires and 1 yellow/green - that's wired in parallel with the compressor so whenever the compressor runs that runs too
the black flex coming out of the top is something to do with the fan
looks like the fan runs on a timer, probably so when the compressor stops the fan keeps going for a little while
bundle of cables bottom left are for the remote start/stop and the waring lights
there's 2 white wires bottom right not used, both go to the same connector block, they're coming for the motor, I'd guess an internal thermal overload which hasn't been used
there's 2 white wires coming in with the black flex on the right, I'd guess same thing for those, thermal trip, not used

at a guess, I'd say there was a problem with the old fan control (maybe duff timer?) and they wired it in parallel to the compressor motor so as the compressor runs the fan runs too

sliver box bottom right looks like a transformer (hard to be sure from photo) - it's wired direct to two phases of the incoming power - it doesn't look like the outputs is used but maybe I just can;t see it in the photo - it probably is/was for the warning lights and remote on/off buttons - so your remote panel would only be low voltage (to make it safer if it got wet/damaged etc.)



there's a couple of places I've had to guess or make assumptions because it's hard to be sure from photos ,but most things are pretty obvious

 

[normspanners]

6 wires coming from the motor, so you can wire in star delta if you want.... but it's wired directly into star

If it was wired star then three of the coil ends wires would be joined together on one terminal, from what I can see each end of each coil are connected to the opposing phases so they are wired DOL delta IMO

wiring looks pretty bog standard for a compressor to me

Sorry that doesnt look bog standard for a compressor to me, also what are the red loops along side the timer -------- all about ? and why do the cables from the overload go to the bottom of the smaller contactor ?
as said the vfd IMO on the diagrams that was designed to 'overrun' the motor to ramp up the motor to higher than usual speed so running a smaller frame 4pole motor at roughly twice its normal capacity/speed by upping its frequency.
quite a good idea really for a hydrovane because the air they produce is directly proportional to the speed, his has slightly more effect than a piston compressor which struggle breathing after a certain speed , BUT the faster the motor goes the more air the motor cooling fan will push over the coils to keep it cool but only need a limited supply for starting, because of the slow ramping up.
Star delta starting on a normal compressor or a fan, is a right pain getting the change over time right and can be less stressful on the motor if the delta cuts in after a VERY short time, poss half the normal S/D time because the motor is too strained in star as the load is ever increasing as the speed/time increases, or yet again a different style starting can be employed that I have played with using another contactor and big resistors or somesuch for closed transition changeover starting to reduce starting transients.
To be fair I am not an electrician, but i have a fair idea of various methods of starting large fans and compressors, that I have played with over the years, I have not done a lot with hydrovanes but they still just compress air which is allways difficult to get started and up to speed reliably, especially if air storage and auto compressor switching is involved.

 

[knighty]

If it ws wired star then three of the coil ends wires would be joined together on one terminal, from what I can see each end of each coil are connected to the opposing phases so they are wired DOL delta IMO

I said it's in delta right now, but there's 6 wires there, so you *could* wire it for a star delta start if you wanted to

EDIT: I typed star when I meant delta

Sorry that doesnt look bog standard for a compressor to me

bog standard for a compressor with a few extras, like a fan and remote on/off switch with on/off/trip warning lights



tona955 hasn't been back in a while, his instincts to wire into the first contactor were right - but connector block to right is easier

if he posts up a pile more photos it could all be figured out... but he's probably wired it in and happily using it right now

 

[Ton-up]

Wire as knighty said, 3 phases into middle beige blocks. Its wired dol. Should have continuous load/unload or turn on/off switch on other box.

and why do the cables from the overload go to the bottom of the smaller contactor ?

They don't. If you follow the cable no's. Phases go into top of large contactor, through o/l, then to top of second contactor then to motor wires.

 

[normspanners]

They don't. If you follow the cable no's. Phases go into top of large contactor, through o/l, then to top of second contactor then to motor wires.

sorry I am getting myself confused, I started typing why dont the cables from the overload go to the motor terminals instead they go to the bottom of the small contactor ? that means there is no point in the second contactor ?

 

[knighty]

sorry I am getting myself confused, I started typing why dont the cables from the overload go to the motor terminals instead they go to the bottom of the small contactor ? that means there is no point in the second contactor ?

they don't, they go up between the contactors, out the top and then over to the right

 

[normspanners]

Wire as knighty said, 3 phases into middle beige blocks. Its wired dol. Should have continuous load/unload or turn on/off switch on other box.

it has an auto pressure switch in the control box it is not continuous load IMO

 

[normspanners]

they don't, they go up between the contactors, out the top and then over to the right

ERM

50---60---70 go from the bottom of the smaller contactor to the motor terminals

 

[tona955]

HI Chaps,
Apologies for the delay in responding....family issues etc.
I was in the unit yesterday and wired up to the white connector block sitting left most. upon applying the power to the compressor it does not startup all I hear is a relay clicking.
I have just read through your suggestions and will try the beige connector block today. In my first pic of the isolator switch, it shows 4 wires connected and the blue wire has the symbol of a switch, where does this blue wire connect within the compressor, I see L1, L2,L3 only.
I have emailed the chap I bought the compressor from and asked if any of the original wiring has been tampered with or modified.