Ronk 15HP - Phase Convertor Help

Good Evening all, I picked up a 15HP Motor off a farmers Old Grain Blower with a Data Tag stating the phase is 1 or 3 phase .... the motor and control box was made by Ronk Electrical Dated 1973 and for the price i could not pass it up, Figured it would be a great replacement for my American Rotary 5HP (My cnc Lathe just hates the slow ramp up on the spindle)

So got it all wired up and powered it up everything runs fine so I figured I could just tap the 3rd leg and pull it into my 3 phase breaker box wrong when I check the generated leg L1-L3 and L2-L3 383 volts then check L3 - ground its the same 383 Vac. I knew something was up so I pulled the motors wiring housing cover off making sure the motors windings was wired correctly and its only a 8 lead motor the diagram in the cover only has wiring diagram for single phase, But the schematics in the control box states it can be wired single or 3 Phase,

Before I call RONK and ask if they know anything about this has anyone ever seen a 8 Lead wiring for windings on a motor Or even a motor that states on the data plate that if can be wired as a single or 3 Phase motor?

Also the run cap bank in the control Box are only between L1- L3 could this just be a unbalanced issue adding caps to L2-L3 correct it.





Sorry for all the run on questions just frustrated.
Thank You
Matt

FIRST: BE SURE THE VOLTAGE READING IS CORRECT.

What meter are you using?

What is it set to?

Where are you putting the meter leads, on what terminals?

What do you get when you read the incoming voltage?

This needs to be answered in full before we can have any idea what is going on.

That is like mine, which is an ARCO, also wired from one side, but in mine they are combined start-run, since it is smaller.

I do not think the issue is that. If you get reasonable voltage readings on the input voltage, you may have more oil type run capacitors than required, however. Up to a point, the more you connect, the higher the voltage unloaded. I have not seen that high, but I have not seen everything.....

Are the box and motor a matched set? They appear to be, but I don't know if they are, because they are separate. The number/size of capacitors depends on the motor.

You could disconnect some capacitors and see if you can get the voltage down to reasonable level.

incoming Lines
L1-L2 240 As should be in both Single Phase Panel and 3 Phase Panel

L3 is my Generated Leg when I refer to L3

I Also hooked my American Rotary Phase Converter back up Checks fine
American Rotary 5HP
L1 - L2 240
L2 - L3 251
L3 - L1 253

My Ronk 15hp
L1-L2 Incoming power 240
L1-L2 To 3 phase panel 240
L1-L3 from Motor Lead 383
L2-L3 From Motor Lead 385
L1-L3 In 3 Phase Panel 383
L2-L3 In 3 Phase Panel 385

its a Fluke Meter I know its not the meter But I verified it Using tektronix Bench top Power supply (I do circuit Board level repairs on a lot of my CNC boards) Just really Stumped my self on this one 383 VAC is Way out range from where it should be having 240 Incoming on L1-L2 Makes me think there is a Winding issue or possible capacitors.

383V tested from Motor Lead and 3 Phase Panel which is L3 in my panel From single phase Leg L1 and L2 to L3(wild Leg)

Yes they are a match set Motor and Control Box

I also have old 3 phase 5HP motor i could wire up to test out loaded just don't want to risk 383V on the wild leg on one of my CNC machines

Hope this clears up some of the missing data

If the voltage measurements are correct, and the motor connections and wiring is OK, then you might need to start pulling off capacitors.

The voltages to ground seem a bit odd . I can sort of see the L2-L3 and L1-L3 voltage, but the L3 to ground should not be the same. It is normally 86% of the phase voltages to L3, so in this case it should be less than the phase voltages.

If anything was grounded that should not be, you ought to be having other problems, though, so presumably that is not the issue. I'm inclined to think you measured from the wrong place and did not notice.

Just to be sure, you might measure from that ground to each of L1 and L2. You had better get 120V on each. Also be sure you do not have any capacitors to ground in some way.

If everything seems correct, disconnect a capacitor or two. If voltages come down, disconnect more until you get around 255 volts L2 or L1 to L3. The ones I am talking about are the oval metal case ones.

You do not actually NEED any capacitors, so there is no harm disconnecting some of them.

Was this being used by the farmer as a motor? Or as a phase converter to run the blower motors?

Thank You JST,
Problem Solve removed 5 capacitors to get it to 252V

To answer dalmatiangirl61 question yes he was using it a motor to drive the blower directly i was more interested in just the motor to build a new phase converter but he included the control box with it to run the motor on single phase which he was using the motor to drive the Blowers and also had a 3 Phase plug he installed to run a Auger he killed 2 birds with 1 stone i guess

Thanks all for the help

Good to hear.

There were only 6 capacitors total, so I am somewhat surprised you had to remove that many, but "It is what it am".

Do you know what the microfarad value is on those?

30 microfarad would of put me at 180 which should of been close or with in range if I am not mistaken 12-16 per hp get you close to balanced