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Building RPC for 3 HP Lathe

SkyHarborCowboy

Plastic
Joined
Jun 3, 2011
Location
SW USA
Here is what I have can you tell me what you recommend I do.

I have a Phas-A-Matic PAM-600HD and Baldor 5HP 3Ph Motor that turns 3450RPM on the data tag.

Can you tell me if I should add Run Capacitors? If so, how many, what size and how to wire into circuitry?

Thanks,

Joe
 
Your box has one capacitor already. It is used as a start and run cap. I suspect you want
to tune it better than that. You will need 40-50uf for one cap and 90-100uf for the other cap.
They get by with such a small start cap because the rotor is built light in weight.
 
Most P-A-Ms are a starting means, only.

I suspect, but do not know for sure, that the so-called "heavy duty" P-A-Ms incorporate both a starting means and a running means.

If true, the starting means would be as before (an electrolytic type capacitor), but the running means would be a run-type capacitor.

(OTOH, I have heard, but have not verified, that a "heavy duty" P-A-M is, quite simply, a regular duty P-A-M, but with a properly rated start-type capacitor, IOW, 250 volts for a 240 system, rather than 125 volts for a 240 volt system, and with no run-type capacitor at all).

In any case, the BEST converter is almost certainly a combination start and run means converter, usually incorporating a potential relay and a start-type capacitor for starting, and a pair of run-type capacitors for running.

Usually, a 60/40 percentage imbalance gives the best results, with the starting means being placed across the 60 percent side.
 
Most P-A-Ms are a starting means, only.

...

(OTOH, I have heard, but have not verified, that a "heavy duty" P-A-M is, quite simply, a regular duty P-A-M, but with a properly rated start-type capacitor, IOW, 250 volts for a 240 system, rather than 125 volts for a 240 volt system, and with no run-type capacitor at all).

...

I will verify that the "Heavy Duty" Phase-A-Matic is nothing more than the regular "Medium duty," but with a capacitor that has higher voltage rating. Because I burned out the Medium Duty model, I ordered the Heavy Duty model and then opened and compared the components. Here is the thread on this forum that tells my story:

http://www.practicalmachinist.com/v...vfd/static-phase-converter-burned-out-100791/


Joe:
As it turns out, I did the same thing as you are trying to do - make a rotary phase converter with a 5hp idler, for a 3hp lathe. I have considered adding run capacitors, but have not done so yet. If you do, please let me know if you notice any difference from the run caps.

-Jon
 








 
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