1. ## Motor Generator

I am about to move my entire hobby shop from the USA to Poland. That would include Bridgeport, Logan Lathe, Harig surface grinder, Sunnen hone, assorted band saws, assorted pedestal grinders and numerous 115V hand tools. No I really do not want to dispose of them all and start over, as I have rebuilt most of these machines.

Given that Poland has either 230V 1Ph or 400V 3phase (all 50 Hz), and all of my machines are either 115v 1Ph, 230v 1Ph or 230 3Ph (all 60 Hz), I have been investigating the possibilities. I see that there are two problems:

1) Voltage and how it is derived (in the case of 230V single phase and 115V single phase).
2) Frequency conversion.

I am quite prepared to wire my new shop in Poland using a US based breaker panel and US based electrical sockets for 115V and 230V 4-wire.

One consideration was to get a large supply side transformer to take 400V 3Ph-50Hz to 230V 3Ph-50Hz (with the 230V being of the "high leg" configuration). However all of this would still be at 50 Hz. I had thought about then using a large VFD (230V 3Ph-50Hz in to 230V 3Ph-60 Hz out, and connecting this to the electrical distribution panel. From this I could derive 115V circuits which would also be 60Hz.

The second alternative would be to use a Motor Generator. I have a 15HP unit in mind that has a 1750 RPM 460V 3Ph-60Hz motor driving a 1600 RPM 230V 3Ph-60Hz (high leg) generator, via a multiple belt pulley arrangement. I found one of these at a reasonable price (900 USD). What would be the effect if I ran the 460V 3Ph-60Hz motor at 400V 3Ph-50Hz? If it changes the speed of the motor, then I would have to change pulley diameters to make sure that the generator gets back up to the speed required to generate 60 Hz?

The third alternative would be to buy a 15KW natural gas powered generator that put out 230V 60Hz power and run that into the distribution panel.

I would appreciate any insight from those who may have more experience with such a dilemma.

Regards,

Paul

2. Running the 460V 60Hz motor on 400V 50Hz is questionable. It will run at 5/6 the speed, i.e. about 1450 rpm which could be corrected by the belt drive, but it is not going to develop 15hp on the lower voltage.

Running a VFD into a panel is a No, No; VFDs have to be wired directly to the load and any switching has to be on the input side. Switching the output side of a VFD is probably going to destroy it.

The natural gas powered genset would work, I use a diesel 15kVA unit to run two CNC machines and it works just fine.

But why not consider getting a 15kVA generator then when you are in Poland get a 20hp 400V motor to drive the generator. The reason I suggest overpowering the motor is to take into account starting surges from your machines.

3. I would look at changing all of your 230v 3phase equipment to VFD. Using individual VFDs that is.

Also, as backwards as this sounds, change all of your 1ph 230v equipment to 3 ph 230 equipment. Then install individual VFDs.

Polyspede has a "phase converter" line of single phase input VFDs called Spedestar. They are for 5hp + motors. I think that they can be found on ebay.

I dont know about the 120v 1 phase equipment.

good luck with the move.

4. Although the UK is not Poland, I suspect practice here is closer than US methods. In the UK, most electrical equipment used on building sites is 110/115V 1 phase, even though the supply voltage is 230/240V. I think this is a safety thing. So there is a ready supply of step-down transformers, which would seem a good route to go for some of your equipment.

All of my workshop equipment has control gear and motors that will handle 50 or 60Hz. The speed charts are doubled up to give both sets of speeds. I suspect all of your single phase stuff will run just fine, but a bit slower. Most of my three phase stuff has motors that can be wired in star or delta format, so can handle either 230/240V from a single-to-three phase VFD, or 400/415V from a direct supply. You might like to check if your motors can take an alternative wiring to run from the higher voltage.