Rewire a 230v motor to run on 120v

by Greg
(SC)

Hello. I just purchased a Hansa HTC 20A from the Netherlands and totally forgot that they use 230v/50hz over there. So before I buy a step up voltage transformer I'd like to see if it's possible to rewire it to run on 120 volts. Do you happen to know if this is possible?

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Mar 11, 2016
kill-a-watt
by: Doug in s.d.ca

Super-duper!

Most amp/power meters are only good for steady state readings. Which is to say you won't usually see a high current spike.

If a spike is big enough, it can blow even a slo-blo almost instantly.

With that in mind, be aware that this fuse may be weakened over many starts, and eventually blow.

No worries so long as everything stays cool and odor-free.

Mar 10, 2016
It's Working!
by: Anonymous

I went to Radio Shack and picked up a few 6.3 amp slow-blow fuses and that seemed to do the trick.

I ran the compressor for about 5 minutes and the transformer (the 450 watt one) didn't even get warm or have any odor at all.

I then plugged in a Kill-A-Watt meter to the outlet and plugged the voltage transformer into it. It reads only around 175 watts and 2 amps when the compressor kicks in. Doesn't seem to make any sense unless the Kill-A-Watt meter needs to be in between the compressor and transformer to see how many amps/watts are being drawn through the transformer?

Anyways, thanks for all the help guys, I really appreciate it.

Mar 10, 2016
watts up
by: Doug in s.d.ca

I think that's the section, Gregg.

Which works out to around 500watts in your case. so the 450 probably should work, except that the design of the transformer is probably minimal (cost) so it may be clipping the output, which motors hate.

Hopefully this third try will be big enough.

BTW, is the pump making any noticeable effort to start while it's blowing the fuse?

Mar 10, 2016
Question
by: Greg

Hey Bill, where's the page about in rush voltage you're talking about?

(A good start here and it's referenced on other pages as well: http://www.about-air-compressors.com/compressor-power-supply.html)

Mar 10, 2016
Transformer
by: Greg

I think they are slow blow fuses. Labled 52T and 5 amps. I'll try an 8 amp slow blow fuse and monitor it like you said.


Mar 10, 2016
fuse
by: Doug in s.d.ca

What type fuse is in those transformers?

I suspect standard quick-blow.

If so, try a slow-blow, same amperage.

You can play with fuses so long as you don't go overboard (10X amps, for e.g.) and you monitor it closely while experimenting. Monitoring means for bad smells/smoke and too warm to touch comfortably.

Mar 09, 2016
Transformer for Compressor
by: Bill

See the page on this site that talks about "inrush power" versus "running power.

While your compressor may run on 135 Watts, the inrush power required to start the motor is hugely more than that.

Mar 09, 2016
Transformer for Compressor
by: Anonymous

Oh... it's been rough. I went ahead and bought a 350 watt transfomer and as soon as i turned the compressor on, the fuse blew in the transformer.

So I decided to go ahead and try the 450 watt model and the exact same thing happened.

So now I'm contemplating giving the 850 watt model a try but wanted to see what you guys had to say about this.

Seems kinda weird that the compressor is only rated at 135 watts and it caused a fuse to blow in a 450 watt transformer but I know virtually nothing about electricity.

I'm starting to wonder if the compressor really does run on 135 watts. What do you guys think, does it seem hopeless to give the 850 watt transformer a shot?

Feb 22, 2016
Motor
by: Doug in s.d.ca

What Buster said.

Also, while I do not have any personal experience with this particular situation, I can say this:

The rating of the transformer (if you go that route) obviously should be at least equal to the load. That's where it gets tricky. As you likely understand, the startup current/power is often MUCH higher than the running power. A well designed transformer should be able to handle a brief (some, even an indefinite) overload without damaging itself. That doesn't necessarily mean the output will be useful and able to start your pump motor.

Ideally, if you can find a shop that sells those, they can advise or at least let you try a couple to see what works. If it can start the motor and the voltage is correct once it is running, it's big enough.

Feb 22, 2016
50hz vs 60hz
by: Buster

Hey Greg, the rating on the pressure switch is what it was designed to operate at. All the pressure switch does is open the electrical circuit and stop the motor at the preset pressure setting restart the motor when the pressure drops below the setpoint. Just like a light switch on the wall controls the light, on or off.

I agree with Doug, it would be a lot more economical to just run a 240 volt circuit and change the plug on the compressor. The motor will still run 20% faster on 60hz power, even with a transformer setup!!

I don't know how tight they designed the unit with regards to loads, but it may overload the motor with the increase in speed!!

Check the FLA on the data tag, this is the maximum amps the motor can pull with out damaging the windings. Maybe their engineering department can help you out.

Buster

Feb 21, 2016
230 to 120v
by: Greg

Thanks for the replies. I already sent an inquiry about this through harder-airbrush's website, but who knows if I'll ever hear back from them or how long it will take.

I don't know if it's of any help but on the pressure switch it says 50-60hz. Which makes me wonder if the motor is also setup to run at different frequencies. http://www.artisantg.com/PLC/80531-2/Condor_MDR_2_EA_11_Eleven_Bar_Pressure_Switch

In case I do go with a transformer, is Krieger considered a good quality brand? And a unit rated for 350 watts should be sufficient? I've read different things from different people about this. Some say to get a transformer that's rated just a few watts more than the compressor uses and others say to get one with double, or even triple the wattage. My compressor is 135 watts.

Feb 21, 2016
120 v 220
by: Doug in s.d.ca

First off, might be easier to just run a 240 outlet if you plan on using it in one place. Rewire may be possible but not likely.

You may be able to replace all or part of the motor for a 120v unit. We've seen that with at least one other unit (diff mfr).

Otherwise, yeah, looks like the transformer would be the way to go.

E-mail: hansa@on-line.de
Internet: http://www.hansa-airbrush.de

(in case you don't have the manual yet)

Good luck and please post back what you decide.

Feb 21, 2016
50 hz vs. 60 hz.
by: Buster

Hey Greg, to determine if the 240 volt motor will run on 120 volts should be on the data plate label. Coming from a country that doesn't use 120 volt, I doubt it is a dual voltage motor. A trip to the motor shop and they could look at it and tell you pretty quick if it could be done. Keep in mind, a motor runs at the speed it's designed to run at directly related to frequency. Increasing the supply frequency from 50 to 60 will effectively increase the speed of the motor by 20%.
Buster

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