Motor configuration

grumpyjohn01 · Apr 26, 2025

Hi all,
I have a customer who has bought at great expense a machine directly from a Chinese supplier for a specialist mushroom cultivation task and he has asked me to install.
I have identified immediately some pretty serious safety issues that need to be addressed but skipping over those for now, my main interest atm is the way the main, pretty huge single phase motor has been configured.
I have attached a drawing of the way I would expect a single phase motor with start and run capacitors to be set up and the way this one has been supplied.
Motors are not my field of expertise but I am familiar with the basics and have not seen one configured this way before so am seeking some reassurance that it is valid. The supplier sent a video of the machine working, (rigged up in a workshop in a lashed up style) but so far I haven't tried to run it. What do you think?
Thanks John

UNG · Apr 26, 2025

I'm not sure either of those setups will work the "our setup" has one capacitor across the start winding and the other capacitor and both the capacitors and start winding would be disconnected when the switch opens
I have found this diagram which should steer you in the right direction

And this link has other diagrams

https://in.pinterest.com/pin/motor-wiring-diagram-single-phase--587930926362247640/

grumpyjohn01 · Apr 26, 2025

Thanks, pretty sure that diagram is the same as my standard setup, I know and understand that that will work. The 'our setup' is how the motor is wired from the factory and does not look like it will work, it may however have been wired differently to the 6 terminal box ( U, V & Z ) I haven't been there to test only relying on photos, I'm reluctant to energise it as supplied and was hoping somebody might recognise an 'alternative' config for 'some' motors

Avo Mk8 · Apr 26, 2025

grumpyjohn01 said:
Thanks, pretty sure that diagram is the same as my standard setup, I know and understand that that will work. The 'our setup' is how the motor is wired from the factory and does not look like it will work, it may however have been wired differently to the 6 terminal box ( U, V & Z ) I haven't been there to test only relying on photos, I'm reluctant to energise it as supplied and was hoping somebody might recognise an 'alternative' config for 'some' motors

Your standard setup doesn't show any difference between 'forward' and 'reverse', did you intend to label eg the main winding terminations the other way round in the reverse version?
The reason I mention it, is that clearly the manufacturers 'our setup' is not going to reverse the motor by swapping L and N over! If reverse is a required feature, and the machine has been shown to work, there must be more to this than meets the eye.

Also I don't understand the purpose of the capacitor that is between L and N while the start switch is closed, with apparently nothing in series with it!

I've come across an alternative approach to reversing, see below (not saying this is necessarily relevant to your situation/motor) - just something to look out for!

grumpyjohn01 · Apr 26, 2025

in the forward and reverse standard drawing the polarity is reversed on the main winding. Tbh I'm more concerned with the 'our setup' case. You are right there is more than meets the eye but I didn't want to confuse things, there is a reversing contactor arrangement with a 4 wire connection to the motor but I have shown on the drawing which terminals are supplied with L and N in each state.
I am now starting to wonder if the 6 terminals are not internally wired as one might expect (U1 & U2 main winding Z1 & Z2 start winding and V1 &V2 switch)
When I get time I will draw out the exact setup as supplied.
There are so many things wrong with the machine, (no earthing at all, no interlocks on reversing contactors, no motor overload, no proper start stop or em stops etc) that I have to also sort out but I was just trying to get to grips with how the motor is configued first because it seems so wrong!

grumpyjohn01 · Apr 26, 2025

the drawing shows the contactor arrangement, the control just energises 1 or the other for forward or reverse, the pic shows the wires 1-4 connected to their respective terminal, I just turned all of that into the 2 diagrams

grumpyjohn01 · Apr 26, 2025

oh yes and of course the blue and brown wires are the capacitors

brianmoooore · Apr 26, 2025

Avo Mk8's diagram (post #4) is for small motors only, where the start and main windings can be, and are, identical.

brianmoooore · Apr 26, 2025

In the OP's standard set up, there's a mistake, in that forward and reverse are identical. Either U1 and U2 or V1 and V2 need to be swapped around to reverse the motor.
The 'as supplied' diagrams are clearly nonsense. Swapping live and neutral won't do anything, and the run capacitor is simply connected directly across the supply in the start phase, also doing nothing.

grumpyjohn01 · Apr 27, 2025

brianmoooore said:
In the OP's standard set up, there's a mistake, in that forward and reverse are identical. Either U1 and U2 or V1 and V2 need to be swapped around to reverse the motor.
The 'as supplied' diagrams are clearly nonsense. Swapping live and neutral won't do anything, and the run capacitor is simply connected directly across the supply in the start phase, also doing nothing.

U1 & U2 are reversed in my standard diagrams

grumpyjohn01 · Apr 27, 2025

I was working from this diagram as a 'standard' setup, however this is shown with links in the terminal box so that the motor is set to be either in permanent forward or reverse depending on link config, I was trying to show in my original diagram in post #1 what I would expect it to look like on the actual machine with the 4 wire and contactor arrangement in post #6 and what it actually is from interpreting the contactor arrangement and wiring of terminals in those images

grumpyjohn01 · Apr 27, 2025

bearing in mind that we have a video of the machine working in the factory, what could be going on?

Avo Mk8 · Apr 27, 2025

grumpyjohn01 said:
in the forward and reverse standard drawing the polarity is reversed on the main winding.

Apologies. I didn't initially spot that although windings are shown in the same place with the same nomenclature, the wiring is different in both forward and reverse diagrams. All good!

grumpyjohn01 · Apr 27, 2025

Avo Mk8 said:
Apologies. I didn't initially spot that although windings are shown in the same place with the same nomenclature, the wiring is different in both forward and reverse diagrams. All good!

Thanks for your input, much appreciated, still wondering what the hell is going on though, I am going to go there this week and do some testing hopefully that will reveal something

brianmoooore · Apr 27, 2025

grumpyjohn01 said:
U1 & U2 are reversed in my standard diagrams

Apologies from me as well. I still had to look twice to spot it. The unusual way you've drawn it almost creates an illusion,

grumpyjohn01 · Apr 27, 2025

brianmoooore said:
Apologies from me as well. I still had to look twice to spot it. The unusual way you've drawn it almost creates an illusion,

No worries , I get it's done oddly but its because of the 4 wire setup that I'm dealing with, when I did the drawings I suppose I had that in mind. Still struggling with what is going on if you have any further ideas!

Marvo · May 2, 2025

What size motor is this? You get lots of winding scheme variations such as perm split cap (PSC), cap start/cap run (CSCR), cap start ind run (CSIR), resis start/ind run (RSIR), they also sometimes cheat and it doesn't connect like any of the already mentioned.

I'd just leave it as it was wired by the OEM and test run it with a couple of clamp meters attached to monitor start and run current and a thermal camera to check winding temp after a 10 second run then a 30 second run and build up lowly until you're sure there's no overheating. Then do the same in reverse run.

If it's incorrectly wired that's how it was supplied and the OEM already confirmed with a test run so that's between the customer and his supplier. Damage won't occur immediately, worse case it would take a fair few seconds for the windings to overheat.

grumpyjohn01 · Thursday at 12:31 PM

Hi again all, Thanks for all the contributions to this thread, just thought I'd post an update and another question!

I have not been able to give much attention to this but finally managed to visit the site and carry out some testing which revealed a straightforward solution - the nomenclature on the terminal box on the motor was simply incorrect, U, V & Z mixed up, when rearranged it was wired as a 'standard' setup. Good.

Now I am on to solving all the other issues and have ordered parts as the reversing contactors supplied had no interlock (mechanical or electrical) and no overload.
I have now sourced a reversing contactor arrangement that has all of those features, however I have realised that with the 4 wire setup to the single phase motor, 1 wire will bypass the contactors and be permanently connected (this could be L or N I guess as 2 of the 4 wires are permanently L & N respectively whereas the other 2 switch polarity depending on desired motor direction.) therefore also bypassing the overloads.
Question is , for a single phase motor such as this, do both L & N need to pass through the overload or just (for arguments sake and most likely) just L? . If both I guess I need to find a 4 pole overload as a standalone (not hanging off T1-T3) or put a 3 pole standalone upstream of the contactors? If only L needs to pass through I can stick with the arrangement I have.
Thoughts anyone?
Thanks!