How to connect a DC speed control to 230 volts

[redgreener]

Hello all,
I need a little help in figuring out how to connect my Leeson Speedmaster 174308 DC motor speed control to 230 volts. Connecting to 120 is simple; just hook up the leads to the two indicated posts. However, for 230 volt operation, the manual simply shows using the SAME two posts, and flipping the required jumpers. So what happens to the Neutral? Where does neutral connect? I need a third terminal,and there doesn't seem to be one. What's the deal here? A few suggestions Please...for the sake of my sanity!
Thanks,
redgreener

[TOTALLYRC]

Originally Posted by redgreener Hello all, I need a little help in figuring out how to connect my Leeson Speedmaster 174308 DC motor speed control to 230 volts. Connecting to 120 is simple; just hook up the leads to the two indicated posts. However, for 230 volt operation, the manual simply shows using the SAME two posts, and flipping the required jumpers. So what happens to the Neutral? Where does neutral connect? I need a third terminal,and there doesn't seem to be one. What's the deal here? A few suggestions Please...for the sake of my sanity! Thanks, redgreener

I am sure someone will jump in, but if I remember correctly, the neutral doesn't get used.
You just use the 2 hot wires and cap the neutral so it doesn't go anywhere.

Mike

[Al_The_Man]

No, you do not need a neutral, the jumpers are usually to set the control transformer from 120 to 240, the SCR circuit stays the same.
Al.

[redgreener]

Cap the neutral? Hmmm, that's very interesting....a good ground will be essential in this setup. Okay, I tried the controller this way, and on the 180volt setting I am only getting around 160 volts out, feeding my Baldor 180 volt motor. Is this typical output for these controllers, or should I be getting more voltage? Other than that, it does seem to be working as it should...
redgreener

[TOTALLYRC]

Originally Posted by redgreener Cap the neutral? Hmmm, that's very interesting....a good ground will be essential in this setup. Okay, I tried the controller this way, and on the 180volt setting I am only getting around 160 volts out, feeding my Baldor 180 volt motor. Is this typical output for these controllers, or should I be getting more voltage? Other than that, it does seem to be working as it should... redgreener

On the controls that I have at work, there is a pot to control maximum speed, which will limit the max voltage out of the drive.

Mike

[redgreener]

Yes, the speed trimpot is maxed. I notice when set to 120 volts this controller will output around 110 vdc; I was just kinda wondering if 160 dcv out or so max was typical output of these types of controllers when set on 240 volts.
Chris

[Al_The_Man]

The reading you are getting may be due to the nature of the DC, 100% ripple at 120hz.
Ideally you should be getting complete full wave rectification at max speed.
Measure the rpm for a given voltage and see how it matches up with the motor plate info.
Al.

[redgreener]

Thanks for the responses guys, I appreciate it. Al, you are right on there, I only wish I had a way of checking motor RPM at max speed--then I'd know exactly where I'm at. It's hard to tell what you've got when fiddlng a motor/controller combo without actually having it on the machine, so I decided to go ahead and put the setup on the lathe. It does seem to work fine; loads of torque and adequate speed.
Actually I think I made a slight miscalculation. I converted a small lathe a while back to a similar setup, a 1/2 HP DC motor in this case as it is a small lathe. The original motor was rated 1750 RPM, and this is what I stayed with. For some reason this speed stuck in my mind and that is what I got for my larger lathe. After some reflection, I now believe its original motor is in the 2500 RPM range--as is typical of a lot of imported machinery, the motor isn't marked, and the manual is NO help. Since this gear-head lathe had a max speed of 1550 RPM, my top speed is now more like 900 RPM. For the work I do, however, this is acceptable, so I'm not going to worry about it. OTOH, the lathe has plenty of power, and it's a trade-off I am satisfied with.
Chris

[Al_The_Man]

If you fit a DC spindle again it pays to look out for one with a tach as most of these SCR drives take tach feedback for tighter speed control, also if you know the dcV/rpm you can quite accurately measure the rpm this way.
Al.

[vger]

Chris,
Take a look at this site...
http://www.sillanumsoft.org/prod01.htm
You should be able to use either the spectrum display or the frequency meter for a temporary tachometer. A sine wave pickoff for the shaft can be done with a small magnet oriented so that the poles are perpendicular to the shaft. Then just a small coil brought near the magnet (while the motor is running) will produce a reasonable sine wave for input to the sound card.
Steve

[dan_barber]

LEESON Speedmaster Drives & Motors Distributors

[Al_The_Man]

What has a AC VFD got to do with hooking up a DC motor? and controller?
Al.