rotary phase converter: Q's about old unit: Do oil-capacitors get old/need replace?

[weekendBuilder]

I am at monkey-level when it comes to electrical. I got a rotary phase converter. I was told it was made ~ 10-13yrs old and the fellow used it just a bit in the first year or so. See 5 pics below - found papers inside the box. Motor looks like some Viet Nam era contraption to me - perhaps used to spray agent orange or such. No tag on it.

I guess a knowledgeable person would listen to it run, and also know if it needs to be greased or rebuilt/forfeited.

I have a double-breaker (30amp) 220 out to my garage. In my breaker-box, I noticed a double-40. So, I am not sure why I ran that double-30 and and not a 40amp. The 40 is not even in use. So, I could switch the breakers (verifying the Home Depot 220-wire is good for 40amp).

Q1: Is my 30 Amp 220 to garage sufficient for this converter?

Q2: Should I wire up the ends and try it?

Q3: Wondering if, for example, do the oil-capacitors dry out and need replacing?

Q4: Does the motor need grease? maybe its so old that there are no sealed bearings.

Q5: What is the red reset-type button on top? (sorry. It is just barely visible at shaft end, under my tape measure 17" point)

I have emailed a guy who builds rotary phase converters. I was going to just bring it to him and pay him to check it, give me orientation to it, etc.

But he is a couple hours away. If I had guts, and nothing ages within the box - perhaps I need to man up and try it. Maybe learn to listen for motor health.

Aim is to run, one at a time, a 7.5 Amp Dayton dust collector or 5HP 80-gal. compressor (unless I can just sell the compressor.


Thank you for your guidance. Mike

 

[Cruzan80]

If the phase converter can start a 10HP motor, it will draw more than 40A @ 240V 1ph. Does the motor have a plate on it showing it's information?

 

[jar944]

Should be a 20hp idler. The data plate would help.

Something between a 50 and 100a circuit

Typical 20hp rpc:

 

[wyliesdiesels]

no way that 30a or 40a circuit will be large enough.

 

[u3b3rg33k]

no way that 30a or 40a circuit will be large enough.

Agreed. it says it'll run up to 30HP of motors, so the feeder needs to support that. 30HP*750=22,500VA, PF 0.8, I'd think you'd need a 125A breaker and wire?

 

[weekendBuilder]

Firstly: thanks to the guys who replied to my post.
I did look at an online calculator after I posted my questions. But, i just fixated on the 10HP start.

To cruzan80: There is no visible plate on the motor. But, i will lift it up tomorrow (june 10th 2024). Perhaps, for some odd reason, it is on the underside of the motor.

I have 100Amp service but my home breaker box was re-done / staged for 200Amp service. Would it make sense to give up and just re-sell the dust collector and RPC. Or, press ahead with the 125 amp breaker and line as wyliesdiesels notes? I have never seen anything larger than 40Amp in a house.
Q: jar944 - what is 20HP idler? That is just some parameter of the motor, correct? Not any reference to some 2nd start-motor (which this does not have).

 

[u3b3rg33k]

I am at monkey-level when it comes to electrical. I got a rotary phase converter. I was told it was made ~ 10-13yrs old and the fellow used it just a bit in the first year or so. See 5 pics below - found papers inside the box. Motor looks like some Viet Nam era contraption to me - perhaps used to spray agent orange or such. No tag on it.
*SNIP*

Aim is to run, one at a time, a 7.5 Amp Dayton dust collector or 5HP 80-gal. compressor (unless I can just sell the compressor.


Thank you for your guidance. Mike

depending on your budget and level of patience/interest in learning, VFDs might do for you. fans are easy to soft start, compressors less so - they need good unloaders and proper control wiring, too.

7.5HP == 30A bare minimum w/soft start (35A or 40A likely appropriate). startup ramp time could be as long as you like.
5HP compressor == 25-30A minimum (harder starting = more inrush) startup ramp will have to be fast enough to overcome a stall/drive+motor needs enough torque/amps to get it past the first compression stroke/rev or some good torque boost on the drive (e.g. not a no nameium drive).

you may also want to consider single phase equipment.

 

[jar944]

.
Q: jar944 - what is 20HP idler? That is just some parameter of the motor, correct? Not any reference to some 2nd start-motor (which this does not have).

The motor that makes up the rpc is typically referred to as the idler. In your case it should be 20hp.

 

[weekendBuilder]

Well - indeed, the motor does not have a plate. u3b3rg33k: I did not realize VFD was viable, I thought people avoided them for larger loads. jar944 - Thank you for clarification. I guess i will try to calculate what Amperage circuit is needed, and figure out if thats feasible for a home. Likely, I am best off to cut the cord - go back to 1 phase. Thank you.

 

[tool_scrounge]

My take:

VFDs are great for providing easy variable speed and work great where the VFD is connected directly to the motor. Things like drill presses, vertical mills, etc. But if you have a lot of three phase machines it is expensive. VFDs do not like switches or relays between the motor and the VFD.

For shops with lots of 3 phase machines or machines with lots of relays and controls and/or multiple 3 phase motors (such as lathes with 2 speed motors and coolant pumps), RPCs are probably a better choice.

 

[weekendBuilder]

Thank you tool_scrounge. I am perfectly stuck. Not big money in scheme of life but:
Option 1: $800 for new 10HP RPC that I am told will start my 7.5HP wood dust collector. Sell my 5HP 3ph compressor.
Option 2: buy 1ph 7.5 HP and 1ph 5HP motors to retrofit my dust collector and compressor respectively.
Option 3: Try running the RPC I have. The local RPC-build guy said he'd just rebuild from scratch - did not want to simply try it.
So, instead, I would replace these oil-capacitors, run a 60-100Amp line to garage, and try starting the RPC.

Will check into your VFD. Thank you.

 

[Cruzan80]

I would start at the beginning. Right now, if you only have a 30A breaker in the shop, it probably could only run up to ONE 5HP machine. Even with a 40A breaker, it may run up to ONE 7.5HP machine. So even with getting the dust collector swapped to single phase, how are you going to power the machine making the dust? Do you need a 7.5HP collector, or could you downsize and get some capacity back for use with other tools?

Based off your information:
Option 1 won't run the the new RPC and dust collector as it currently sits. Possibly it would run the compressor. If you were able to swap it to a 40A breaker, it may be able to run the dust collector. You would need to verify wire size used, and voltage drop to ensure wire is up to carrying 40A.

Option 2: Retrofitting the compressor would work. After verifying the wire, and up sizing the breaker to 40A, dust collector should work. See above on how you will power the tool making the dust.

Option 3: Probably your best bet long term, if you want to be running multiple higher HP machines. I would suggest putting in a sub panel, so you can then run multiple smaller lines off the main garage feed, sized appropriately for each load. But it will cost much more than $800, especially if you are going to have an electrician run the new line.

Not an option: Trying to use the existing RPC and machinery with the current power levels (even if it is working perfectly). Best case scenario, all it will do is trip the breaker immediately.