I Re-Commissioned My Static Phase Converter

[MrWhoopee]

I've had enough of the incessant whine of my 7.5 hp RPC, which constantly reminds me that it's using much more power than either my lathe or mill (or both combined, for that matter) whether they are running or not. I reconnected my WNY SPC, which is dead quiet and draws no power. I will keep the RPC on standby, just in case I find a situation where the reduced power actually becomes an issue. It's nice to be able to drill a quick hole on the mill without having to wake the beast first.

 

[projectnut]

I have a 10 hp North American Rotary PRC that's been setting on the shelf since 2016. I even went so far as to have a sub panel installed to power it. The initial thought was to replace the static converters on 4 machines and use the RPC to power them all. However that's where the project got stalled. Somehow running all the circuits to power the existing machines, and a couple extras for future machines not only hasn't materialized, I'm not so sure I'm still interested in doing it.

The static converters seem more than up to the job, and none of the machines have been run hard enough in the last 20 years to say there has been diminished power when running on single phase. I have run the mill hard for 8 and 10 hour stretches with no signs of overheating or lack of power. The same is true of the mill. As for the saw and drill grinder, they never run long enough continuously to even bring the motors up to temp. I used the saw earlier this week to cut some 1" x 6" cold rolled. After a dozen or so cuts I laid my hand on the motor and it was still ice cold.

I'm beginning to think the RPC may be destined to be a dust collector unless I stumble across a machine that can't be run any other way.

 

[middle.road]

pheeeew. Around New Year's I was regretting selling the 10 HP RPC I had. I've been wondering if it was a mistake.
I sold it to get the VFD for the Bridgeport and had some change leftover for some other tooling.
The mill is the only 3PH I have in the shop - so far...

 

[Ulma Doctor]

@MrWhoopee ,
it's always very nice to have the capability of either or !

i would suggest inserting a normally open switch or relay into the generated leg circuit, here is why...
upon start up, the potential relay encased inside the SPC , is set to dump a capacitors charge into the generated leg whenever the voltage drops below a pre-determined value.
during heavy cuts, the potential relay could be called into action many times during a project and the start capacitor will charge and discharge many times per hour, that's bad for a start capacitor that usually likes (or designed) to operate only a few times a day.
i burned up my first static converter that way, and i'd hate to see someone else find out the hard way.
you will need to wire the N.O. switch/relay in downstream of the SPC, and open the switch/relay only after the intended motor has started
a rotary action switch could easily be utilized for this function

i designed a converter and removed the necessity for a potential relay, as a go around- i haven't looked back since.