Help with reading a 3 phase motor diagram

[Phillip Mitchell]

This has been discussed somewhat in another thread, but wanted this to be its own topic so hopefully I can understand this better.... other thread - https://sawmillcreek.org/showthread....per-Wadkin-BEM

I just got this shaper (Wadkin BEM) and am trying to trouble shoot why it won’t start properly on the Rotary Phase Converter. Trying to isolate if the RPC is simply undersized or if it’s currently wired for high voltage. Currently, the shaper motor will start but then trip the contactor overload after 2-3 seconds before getting up to full speed. Removing the drive belt (that connects the motor to the spindle rotation) allows the motor to start and run fine (it seems), which has me concerned. Motor is 12 hp / 27.4 FLA @ 230v and my Kay converter is rated to start a 10 hp Max single motor. I spoke with Kay support and he suggested I confirm the motor voltage wiring first before assessing a few different options that could be added to the RPC to help with the large startup current needed.

Photos attached that show the motor wiring schematic that was inside the junction box on the motor where the 12 motor leads and incoming lines connect. Currently there are (3) line wires coming in from the control/switch/incoming power source and (4) motor leads connected to each line wire. Each set of 4 leads + 1 line is stacked together on a short bolt and tightened with a nut on the end and wrapped in electrical tape.

The way the motor is currently wired as I received the machine is shown (written out) in another photo and does not match either of the diagrams shown on the schematic, neither high or low voltage. I am confused. Why would it be wired differently than what it shown?

I do not have experience in this part of electrical work and do not know how to interpret this diagram. What do the squiggly lines mean compared to the straight lines? I have tried looking this up online and have not come across anything that explains how to interpret this.

The shaper is new to me, but I saw video from the previous owner of the machine running what seemed to be properly just before I bought it and they said they thought it was 240v (metered 3 phase) and it had a 250v plug on it, but you can never assume anything completely just from existing conditions.

Should I re-wire the motor leads as shown on the paper diagram for low voltage and test? What is the risk / harm in doing this?

Thanks for any help!

[Bill Dufour]

Then squiggly lines mean the enameled wires of the coil windings inside the motor. The straight lines are regular rubber insulated wire leads coming out from inside the motor coils.
The straight lines are the wires you can see and actually touch inside the junction box on the motor.
BilLD

[Bill Dufour]

The high/low diagrams make sense to me. High voltage has two mating coils in series. Low voltage has each coil in parallel with its mate.
I am not clear on how three power leads get attached to six out leads.
Obviously some of the leads are paired together with one input, but how?
Once you figure it out some red/blue/black/ green fingernail polish from the dollar store may help mark wires.
Bill D

the green ground is totally correct from the photo!

[Bill Dufour]

I count 12 leads from the motor.
Bill D.
https://control.com/technical-articl...-twelve-wires/

https://electricmotorwarehouse.com/m...tion-diagrams/

[Alex Zeller]

What you'll want to do is carefully pull the wires out and identify the yellow tags on each wire (other than the ones supplying power to the motor). Verify that T1,T6, T7, and T12 are connected together and to one of the power lines coming in. Verify that T3,T5,T9, and T11 are connected together and to the second power line. Finally T2,T4,T8, and T10 should be connected together and to the third power line. If any of the wires aren't connected correctly it'll cause you problems.

If it's wired up for high voltage T1 and T12 will be connected to one of the 3 power lines, T2 and T10 to the second power line, and T3 and T11 to the third power line. I can't see well enough to say for certain that it's wired up in low voltage without having the wires pulled out of the box.

[Phillip Mitchell]

Thanks again Bill.

Thanks to Andrew, I saw few different things online that showed the same wiring I have currently as an appropriate 3 phase 12 wire Low voltage wiring pattern.

At this point I am trying to determine if the issue is with the RPC being underpowered or if something is off with the coil/contactor/overload protection as that is what is actually tripping. The RPC seems fine and is not tripping it’s breaker or sounding like it’s struggling.

I am not claiming to understand this fully, but when I look up the make and model of the contactor / overload protection it shows that it’s rated for a max of 5 HP @ 230v, which makes no sense on a 12 hp machine. What am I missing? Should it not be rated for the full HP of the motor?

https://www.klocknermoeller.com/pkz/pkz2-zm-16-s.htm - it’s this one.

I have a few different messages put out to other BEM owners to try and see what their control box looks like and if the same make/model of overload and contactor is there or not. Still waiting to hear back on that to compare.

[Kevin Jenness]

Can you confirm the voltage supplied by the previous owner? Have you checked the voltage on the three lines coming from your converter? What has changed between now and the video of the operating machine?

It's a frustrating situation, but I'm sure you will work it out. The motor control does appear to be undersized, but if it worked before...? Was the machine recently in service?

Do you have a good industrial electrician available in case your troubleshooting fails?

[Phillip Mitchell]

Can you confirm the voltage supplied by the previous owner? Have you checked the voltage on the three lines coming from your converter? What has changed between now and the video of the operating machine?

It's a frustrating situation, but I'm sure you will work it out. The motor control does appear to be undersized, but if it worked before...? Was the machine recently in service?

Do you have a good industrial electrician available in case your troubleshooting fails?

Thanks for the reply Kevin.

The machine had been sitting for years, was part of a cabinet shop that changed ownership, new owners are not woodworkers and only familiar enough to hit the power button enough to show me that it turned on and ran under power. I have asked about their voltage and they said 240v, but I’m not sure how much they know or if that was where the machine was powered when actually in use. History is a bit murky.

Their video shows a small diameter cutter on the spindle and belt connected / spindle rotating and the machine running at ~ 7 amps via amp meter on the front of shaper.

My testing with removing belt and getting it to run is obviously no cutter / belt to spindle (just motor running) and machine showing ~10 amps on amp meter.

Voltages coming into RPC are ~250v with wild leg around ~280, which is consistent with what my supply has been for years.

What has changed
- metered 3 phase vs RPC in my shop
- new plug - though old plug was also a 30 amp / 250v plug - just wrong prong config for my receptacles

I do know a local electrician that may be able to help me troubleshoot, but always try and sort this out by myself first (for some reason...) Might be worth a call as I obviously have gaps in my knowledge and understanding of motors and electrical in general.

Thanks again.

[Ron Selzer]

based on information provided the motor is wired for low voltage, 208-240 vac, 3 phase
starter is too small based on manufactures info 0f 5 hp and max of 16 amps

[Malcolm McLeod]

... it’s rated for a max of 5 HP @ 230v, which makes no sense on a 12 hp machine. What am I missing? Should it not be rated for the full HP of the motor?

https://www.klocknermoeller.com/pkz/pkz2-zm-16-s.htm - it’s this one.

...

Long shot, but I did not see mention of what the unit's O/L is set for .... 16A? If not, you can crank them up and see if you can run it lightly loaded. (I'd not hold my breath.)

More likely, IF the unit ran with the installed (and linked) starter-O/L combo, it was on 480VAC feed. And likely the 'running video' at 7A was done on 480VAC as well, and to top it off, the previous owner probably could not run it at close to FLA - even on 480VAC. (Or, someone may have pulled the 12Hp starter, installed the existing 5Hp, and re-wired motor to 240VAC just to sell it....???)

As you mention the O/L trips, not your RPC, so I think you have isolated your problem - and as per Mr. Selzer, you need a new starter-O/L rated for 12hp at 240VAC.

********
https://configurator.rockwellautomat...B386B7/summary - This would get you close in A-B's IEC format (closer in size to the Moeller vs NEMA-format); check what coil voltage you want/need.
or
https://www.klocknermoeller.com/pkz/pkz2-zm-40-s-sp.htm - If you want to stick with Moeller.

[Phillip Mitchell]

Thank you Ron and Malcolm!

The overload was set to max / 16 amps. I tried it at different settings and a lower setting resulted in a quicker overload trip, as expected. It is in the photos somewhere, but I think 16 amps is max setting on the dial from what I can see.

This is all helpful and I think getting closer to the solution. I agree Malcolm about it likely being run to testing on 480v, hence the lower amp readings (loaded) compared to my higher unloaded readings.

The question becomes can my RPC handle the load with the correctly sized O/L?

I will do some googling later, but is there a preferred online source/vendor for best pricing on these O/L units?

[andrew whicker]

Scary if they did run it on HV. The motor wiring is clearly for low voltage.

From what I understood, running a LV motor on HV is a great way to hurt the motor. Oth, from what I understand about 12 wires on a 3 ph motor is that you remove the "overload" point that exists on a 9,6 and 3 wire 3 ph motor. So I guess everything is bueno? Although I also think that "overload" point fails when you have coils that no longer have the same resistance. Idk.
Been drinking out of the proverbial fire hose lately.

Lower amperage than expected for the same HP seems like it wouldn't hurt anything?

Curious what the experts think.

[andrew whicker]

Also, how did he and you read amps?

You need to read amps Per Leg to match the amperage to the motor nameplate. To do this you need to separate the lines / wires and measure each phase / line / wire separately.

Each leg amperage should match (about 80 percent of nameplate i think) the nameplate amperage AND drawing the same amperage.

I just did this last night with a much smaller motor. Each leg draws the amperage that is stamped onto the nameplate.

[Bill Dufour]

His machine has an amp meter onboard.
I agree his starter/overload is too small.
You need 30 amps or higher.
Bill D.

Looks like you need one contactor and one overload set. Not sure if your box has enough room for the bigger sizes needed?
https://www.klocknermoeller.com/pkz/zmr-16-pkz2.htm

[Bill Dufour]

Search terms for the needed switch gear, motor starter, contactor, overload.
Some wood working companies recently invented the term "Magnetic switch" so you may see that but only from hobby type sellers.
Problem with ebay is few sellers list amps. Many do not state coil volts either.
You need a NEMA size 2 or larger starter. I would guess you have a size zero in there. You may have to add a bigger enclosure to hold the new switch gear.
Your starter is probably a IEC size anyway not NEMA.
Bill D