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3 Phase in US

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teal95

Solar Enthusiast
Joined
Jul 26, 2022
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Location
Jackson, MI
Working on feeding a couple of plastic injection molding machines in my barn. I'm currently setting up a solar system in the barn (20 kW of panels, 30kWh of batteries, Solark 15k) but need to feed the 8 hp 3 phase motors on the machines. I don't have 3 phase available from the grid. I do have a 100 amp 220 v feed off the grid to support my power draw. The machines also have heaters I need to feed so I'm going to need roughly 20kW to feed them.

I can't use a split phase feed VFD as there seems to be a rather hard limit of 5 hp for using a 220 single/split phase input, and it would exceed what I can get off the inverter I have. The solar installer I'm working with has no knowledge of 3 phase so I'm doing the research on this.

What's available in the US that will support 3 phase off grid? For right now I'm planning on running it off the batteries with the Solark handling the PV, but as it's already at capacity I will use the MPPT inputs if I expand the PV.
 
Using multiple sol-arks you can get 3 phase output, see the diagram in the manual, if you don't have the proper 3 phase tgrid feed you won't be able to use grid power with the sol-arks. Your setup would need to be fully off-grid, with inverters and batteries to handle the full load, and peak demand. You could add a separate battery charger that will charge the batteries from the grid to get some grid power in to this system.
 
There are many options.
Vfd motor controllers, as mentioned, you can get 2 more solarks, or you can install any brand of 3 phase inverters...
 
teal95 said:
I can't use a split phase feed VFD as there seems to be a rather hard limit of 5 hp for using a 220 single/split phase input, and it would exceed what I can get off the inverter I have. The solar installer I'm working with has no knowledge of 3 phase so I'm doing the research on this.
Click to expand...

You CAN get variable frequency drives that will power motors bigger than 5 hp.

Typically you have to dig into the data sheet to see what they are capable of since they might not specify it in short description. Attached is a link to a drive that will do 10 hp from single phase input.

 
What voltage are those motors? 480Vac? You can rewire the heaters to run from 240Vac grid power directly.
 
SolArk is outside the budget for this. The main inverter will feed the house so it's also emergency backup. And the SolArk is 30kW so it's bigger than I really need. I'm a bit more concerned about budget and less about reliability for the 3 phase.
 
VFD is much cheaper than general purpose inverter.
Larger wattage would work best with 3-phase input, might work off single phase.

Consider a step-up transformer (use one designed for that, not a step-down operating in reverse), and turn your single phase grid input into 480V single phase. Maybe a 240/480 to 120/240V step-down wired as autotransformer would serve the purpose.

If using 3-phase inverter not VFD, there is starting surge as mentioned. It is just as high for 3-phase motors as for single phase, but they do have better torque. If they can be wired for multiple voltages, or if you have multiple voltages available, starting at reduced voltage would help.

Several of the inverters can be wired for 3-phase. SolArk, Schneider, Outback, Sunny Island.
I suspect the ones that also do 120/240V split phase in a single inverter could give you both 120/208Y and 240/415Y.
You can also step up, but you need a bettery transformer than typical utility line models. The 240/480 primary windings of a single (split) phase transformer should work well to boost 120V to 240V.

But surge current will be a limiting factor of these smaller inverters. 3x Sunny Island will give 17kW continuous, 33kW 3 second surge. That should handle a 3-phase motor with 6 kVA operating current (check nameplate for LRA)
 
The machines are fairly old. A Boy 12 ton from the mid 80's (built in West Germany) and a Boy 15 ton from the early 90's.

From prior experience with farm drainage pumps the price of single phase motors over 5 hp is also excessive, so replacing the motors probably isn't reasonable either.
 
OK, how about 240/416Y?

You might want 277/480Y, but I've had a hard time cheaply sourcing transformers to do that.

What you can do easily is double voltage from an inverter using the windings of 3x 240/480V to 120/240V transformers.
Put in 120/208Y and you would get 240/416Y.

If you have 3x inverters 120 degrees apart, and they have 2x 120V windings (LF) or switcher outputs (HF) that can be either in series or in parallel, you could use those to make both 120/208Y and 240/416Y

A bit under what a 480V 3-phase motor was looking for, but should work fine.
Here in the US we use 60 Hz. In Europe and some other places, 230/400Y at 50 Hz is common.
 
Both motors appear to be the originals from Germany. Smaller one is 5.5 kW and larger is 6.6 kW. Larger one is labeled 220/380v, 19.7/11.4 A and 60 Hz (picture I took of smaller one was too blurry to read).
 
The SRNE HYP might suit your needs with up to 6 in parallel. If you're interested I can find the baba link I ordered my ASF series from.

Inverter off-grid da 5kw Serie HYP

La serie HYP è un nuovo tipo di inverter solare integrato che combina l'accumulo di energia solare, l'accumulo di energia di carica e l'uscita a onda sinusoidale CA.
www.srnesolar.com www.srnesolar.com
 
teal95 said:
Both motors appear to be the originals from Germany. Smaller one is 5.5 kW and larger is 6.6 kW. Larger one is labeled 220/380v, 19.7/11.4 A and 60 Hz (picture I took of smaller one was too blurry to read).
Click to expand...

Do you think that is 220/380Y? In which case, why two different currents?
Or is that 220 delta at 19.7A, alternately wire as 380 delta at 11.4A?

3x Sunny Island can deliver 120/208Y at 50A per leg, 92A starting surge.
That may be close to LRA for the motor (is that quoted?)

If you can rig a switch to start the motor wired for 380 delta (while feeding it 208 delta), that would knock current down to a bit over half.
Then switch to wired for 220 delta to run.

Since you have SolArk, you could consider two more to make a 3-phase system. It can probably do what I've done with Sunny Island - master inverter gets power from grid, the two slaves make the missing phases. An issue is that grid is 125V while the slaves make 120V.

I think you'll be much better off if you can drive it with VFD. Cost to buy one and try it would be a fraction as much.
Use a step-up transformer if needed on input. Maybe adding more electrolytic capacitors would help, reduce ripple.

Something like this, $750

www.ebay.com

1PC Yaskawa CIMR-VU4A0011FAA, V1000 7.5HP 3-Phase 380-480V 11A VFD | eBay

(Yaskawa, CIMR-VU4A0011FAA, A1000 Drive, AC Drive, VFD, Nema 1 enclosure. excluded.). Output Normal Duty: AC 3Phase, 0-480VAC, 7.5HP, 11.1Amp, 0-400Hz. Input: AC 3Phase, 380-480VAC, 50-60Hz.
www.ebay.com
 
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