VFD for a Transformer

[deetz]

Okay here we go again on this subject about sending machines to other frequency Countries. They want to send a couple of small band saws (120v-60hz) to a 240v 50hz country. If I set the VFD for a max of 120v output, will this work?

 

[waross]

You may be able to run the proposed saws from a modified UPS. Those small band saws are typically universal (brush type) motors and are not compatible with a VFD output.
Actually, for a universal motor it may work well on 120 Volts 50 Hz.
OR
How about one of these?

http://www.milwaukeetool.com/power-tools/cordless/0729-20

It may be easier to power the charger. You may be able to do it with a modified UPS.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

Gotta be easier to buy a European / Australian motor, and more reliable too.

 

[jraef]

120V 60Hz is single phase, you cannot use a VFD on the vast majority of single phase motors. Those that can be run from a VFD would not be suitable for a band saw.

You would have to SERIOUSLY over size a UPS to be able to deal with the starting current of an AC motor on something like a band saw. That would be very expensive.

By the time you get done with all the rigamarole it will take, it will be far far easier to just go out and get 230V 50Hz motors for them. If not, just get a transformer to step the 240V 50Hz down to 100V 50 Hz, which gives them the same V/Hz ratio as the motors were designed for. The motor will run 20% slower, but will produce full torque and not over heat or (shouldn't) over load.

Or buy new small band saws over there that are designed to work over there, saving the shipping cost as well. Sometimes people try too hard to insist on making electrical stuff work in foreign countries when it would be so much simpler to start fresh. They just don't understand what it means.

"Will work for (the memory of) salami"

 

[waross]

If these are hand-held band-saws, they are most likely universal motors similar to drill-motor motors. The hand held band-saws that I use all have brushes.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[deetz]

Yeah, I don't know why they keep buying stuff here to send over there. We do send a container every so often so shipping isn't much of an issue. Sorry I didn't elaborate on the saw. It's like a miniature meat saw. It is just used to cut that mesh type thread protecting material. I did just happen to have a couple of 1kva transformers lying around, but was curious if the VFD would also work for future reference and the motor is just 60 hz, not that maybe the motor would be alright on 50hz. Also wouldn't I want to bump up voltage for 50hz rather than down?

 

[waross]

You should maintain close to the same Volts per Hertz ratio. That means if the Hertz goes down the voltage should also go down in the same ratio.
Aside from the voltage and frequency issue you may also have approvals issues.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[deetz]

Oops, my math is rusty or my reverse dimentia kicked in. I went 120 times 60 divided by 50.