Matching Rotary Phase Converter to Schwabe Clicker

[thrawnny]

Hello all,

There are a few good threads on here discussing the best way in which to run three phase machines on 220 single phase power. While there does seem to be some difference in opinion regarding RPC vs VFD's, I cant find a consensus on how to actually match the motors.

I just picked up a 25 ton Herman Schwabe clicker running a 3 HP motor. Some folks seem to think it's best to match it with a RPC with a larger motor, like a 5hp, while others say a 3HP RPC is adequate.

There's a pretty significant price difference between a 3HP and 5HP converter so I just wanted to see if any of you had a reason why one would be preferable to the other.

Will I have significant power loss on a 3HP converter? Any risk of burning out the motor?

I plan on using a Phase-a-Matic RPC if that helps.

Many thanks for all of your advice.

[480volt]

Phase-a-Matic does offer some guidelines on matching RPC size to motor type on their website. This may be of use to you only in a general way, as you cannot possibly power up the machine and measure the current at full hydraulic load. Their recommendation for most motor loads, including those driving hydraulic pumps, is that the RPC be sized larger than the driven motor. This follows industry practice as I have seen it, where the minimum you would size the source for a motor is 125%, to account for starting and overload. It’s always better to have some margin in the system, things will run cooler and last longer. 

[thrawnny]

Many thanks for the info. So I think I'll go for the 5HP RPC. Sound good to you?

[Sonydaze]

You may want to look at this company: Tempco Power Wave.    5hp. $389

I bought one of their three horse power ones several years ago and it has been problem free.

[480volt]

8 hours ago, thrawnny said:

Many thanks for the info. So I think I'll go for the 5HP RPC. Sound good to you?

That should work fine. I’m currently using a 5 HP RPC to run the 3-horse motor on my milling machine. 

[Mark842]

I have an American Rotary brand phase converter running two 25 Ton clickers at the same time for 4+ years. They are still available on eBay for under $400 with free shipping for the 5HP model.

[thrawnny]

Many thanks to you all for your replies. Huge help.

I spoke with Phase-a-matic. They were incredibly helpful and offered some great advice.

They recommended that I at least double the motor size just to be safe (ie use a 7hp on a 3hp motor) but admitted that a 5HP would do the trick just fine.

 

[chipadd]

Hey Guys,

Im in the process of installing a 5ph rotary phase converter from American Rotary for my USM Model b clicker. Did you install a disconnect switch between the converter and the machine?  and did you install a breaker on your 3phase line?

Thanks