# Paralleling Roto phase.



## 460 Delta (May 9, 2018)

As long as the phase rotation is the same, they should parallel just fine. Well, as long as the idlers are the same make and model and have like capacitance. I briefly paralleled two 60hp Arcos at a former job to see what happens, no drama at all.


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## Forge Boyz (Nov 7, 2014)

So its a matter of checking rotation and turning them on?

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## tmessner (Apr 1, 2013)

Find a 1st year apprentice to turn it on.


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## 460 Delta (May 9, 2018)

Forge Boyz said:


> So its a matter of checking rotation and turning them on?
> 
> Sent from my SM-G970U using Tapatalk


I suppose so, as long as the phase rotation is ABC or CBA with both of them and the single phase lines aren’t crossed, start one and bring the other on in a few seconds.


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## micromind (Aug 11, 2007)

460 Delta said:


> As long as the phase rotation is the same, they should parallel just fine. Well, as long as the idlers are the same make and model and have like capacitance. I briefly paralleled two 60hp Arcos at a former job to see what happens, no drama at all.


Did you synchronize the or just blast them together?


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## emtnut (Mar 1, 2015)

micromind said:


> Did you synchronize the or just blast them together?


That was my thoughts as well.
I've never parallelled them, but would think it's the same as parallel gens.


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## 460 Delta (May 9, 2018)

Synchronized blast maybe? Maybe I was just lucky but I see it as induction generators and not synchronous. I figured the inductive “slip” will take care of it.


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## Forge Boyz (Nov 7, 2014)

Two of the phases are straight through so that shouldn't be an issue. I know where a setup like this is, but I don't know exactly how it works. It does have a "start this one first sign on it, so I am wondering if there is something different in the second one.

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## CMP (Oct 30, 2019)

Paralleling rotary phase converters can be done with mismatched sizes as well as matched ones. Best started with the smallest unit first to reduce the starting strain on the supply line. The first running unit will help start additional units by providing the generated phase. Unloaded idling 3Φ machine motors running on the system can also help support the generated leg.

The 1Φ phase supply legs need to be fed straight through on all idlers, and the manufacured (generated) legs need to be paralleled as well. Rotation needs to be matched on the converters, and is determined by the internal start capacitor and run capacitor connections to which line they are conected, not by swapping phase line connections externally. Factory built units of the same brand will likely have the same start rotation connections. Mismatched units or homebuilt units will likely require checking and possibility reconnecting the start capacitor circuit connection to the opposite phase to change rotation.


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## micromind (Aug 11, 2007)

After some thought, I believe the following but it's only my opinion, no actual tests, nondestructive or otherwise.......lol.

Since there's no slip in a generator, closing in out of phase would result in slamming them to synchronization but since motors do have slip, closing in out of phase would be softer. 

Also, since the single phase lines to each unit are in phase with each other, the manufactured phase would also be in synch provided the rotation is the same on both units. 

Further, there could be circulating currents between the two units, worse at no load than with load. 

Again, just my opinion, not actual fact.


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