Will this work as a step down transformer?

[Don Buck]

I am looking for the most affordable option to hook up a 3 phase 1.5 hp 5.8 amp 200v Delta RAS to my 230v 3 phase (via rotary converter) circuit. I contacted a merchant recommended on this forum about a step down transformer (230v to 200v) and he recommended bypassing my rotary altogether and go with a TECO Micro AC Inverter for $144. The specification are here http://www.tecowestinghouse.com/PDF/FM50(08.04).pdf

Anyone have experience with this or similar device? It is cheaper than any step down device I've found so far but don't quite see how I would select 200 v output. The chart shows output for 230v which is where I am right now. I need to drop the voltage closer to 200v.

All help & advice from the brain trust is greatly appreciated.

Don

[David G Baker]

You haven't let us know what you are trying to power, this may make a difference.

[Don Buck]

Sorry if it wasn't clear - I'm trying to power a Delta 12" Radial Arm Saw, 1.5 hp, 5.8 amp, 200v motor.

Don

[John Baranowski]

Check the nameplate of the motor, and find the manual if you can. The motor may be rated for 230V already.

In addition, this manual shows the settings for changing the output voltage.

http://www.tecowestinghouse.com/Manu...ing_manual.pdf

[Don Buck]

Most 3ph motors on Delta equipment are multi-volt. However, this motor is not and is is a 200 - 208v motor. Delta said I will need to step down the voltage or replace the motor ($900+ for a new motor!).

[Dan Friedrichs]

Don, that VFD you linked to will NOT work for this application - the output voltage is simply proportional to the input voltage, so if you put 240V (single phase) in, you get 240V (3 phase) out.

If you want to use a transformer, you need what's called a "buck boost transformer". Find one that is 3 phase, rated for 240V in and 208V out. These are quite common, and can probably be had for ~$200.

But....I think I would see if I could find a VFD, first. I'm not sure if they make one that will do 240V (1ph) and 208V (3ph) out, but I don't see any reason why they wouldn't, and that seems like a less complicated solution.

[Chip Lindley]

A slim chance there is someone out there who would JUMP at the chance to swap their 230V motor for your 208V RAS motor. Advertise in SMC Classifieds, and also over at OWWM's BOYD (if your RAS is at least 20 years old). Ya' just never know!

[Rod Sheridan]

Don, that VFD you linked to will NOT work for this application - the output voltage is simply proportional to the input voltage, so if you put 240V (single phase) in, you get 240V (3 phase) out.

If you want to use a transformer, you need what's called a "buck boost transformer". Find one that is 3 phase, rated for 240V in and 208V out. These are quite common, and can probably be had for ~$200.

But....I think I would see if I could find a VFD, first. I'm not sure if they make one that will do 240V (1ph) and 208V (3ph) out, but I don't see any reason why they wouldn't, and that seems like a less complicated solution.

Dan, if you set parameter C16 to 200 doesn't the inverter set the maximum voltage to 200 volts?

Regards, Rod.

[Dan Friedrichs]

Dan, if you set parameter C16 to 200 doesn't the inverter set the maximum voltage to 200 volts?

Hummm... you must have found a different manual that I did, Rod. The manual I found has a line that says "Output Voltage Max: Three Phase 200-240V (Proportional to input voltage)", but no mention of setting the output voltage. And parameter #16 relates to braking.

The manual I found is here: http://www.tecowestinghouse.com/Manu...anual_0405.pdf

Did you find a different one?

[Rod Sheridan]

Hi Dan, I used the manual in the original post. page 47. Maybe I didn't understand it correctly however I thought I could set the volts/Hz to a level to produce 60 Hz at 200 volts.......Rod.

[Dan Friedrichs]

Hi Dan, I used the manual in the original post. page 47. Maybe I didn't understand it correctly however I thought I could set the volts/Hz to a level to produce 60 Hz at 200 volts.......Rod.

The link in the OP only shows me a 2-pg PDF?

Maybe I should stop talking before I further reveal my ignorance of AC drives, but I'm not sure there is any technical challenge (beyond just including the parameter in the configuration) that would prevent a VFD from operating below its input voltage. Perhaps its just a matter of confirming whether or not a particular model will do it.

He could turn down the V/Hz until he had 200V, but then his motor would be running at 55Hz. I'm guessing it's meant to run at 3600rpm, so running at 55Hz would take it down to 3300rpm. Probably not a big deal...

That said, 208+10% is 223V, which is pretty close to 230V. I might consider just running it at the higher voltage.

[David Castor]

You should be able to get a VFD that can limit the voltage. I'm not an expert on that particular TECO drive, but in general, it's possible. Most VFDs have a parameter setting for motor voltage. This will be reducing the "horsepower" rating of the VFD a little, but as long as it can output the motor's rated current, you should be OK. The VFD is a current output device and the current output rating is much more meaningful than the hp rating of the VFD.

[Rollie Meyers]

I bought a GE/Fuji 2 HP drive that does offer the option of changing the output voltage, motor was a 200V 3Ø motor & the drive was cheaper then a new motor,if it was not possible to change the factory parameters for the output voltage, option #2 would have been to install a buck/boost transformer to buck the 240V + line voltage to 208V.IMG_0080.jpg

The machine is a 1974 Rockwell HD shaper from a HS in the San Diego area.