Duke University Motorsports is a student group that designs and builds open wheel, single seat race cars to compete in the Formula SAE competition sponsored by the Society of Automotive Engineers. The team consists of Duke students from both Pratt and Trinity, in all classes. The purpose of the team is to provide students with a way to gain practical design and manufacturing experience in a fun and challenging setting.

Wednesday, February 1, 2012

Mill Fixed

So a few days ago our static phase converter stopped converting 1 phase power to 3 phase power and instead decided to convert 1 phase power to smoke.

Luckily, Dr. Simmons (our advisor and an overall great guy) had an extra VFD lying around, so I've spent the past couple days attaching it to the mill.  You'd think that something like this would be a simple wiring job, but of course it turned out to be more complicated than I would have liked.
Our new VFD, attached to the side of the DRO.  It works with the original mill controls, and provides a handy current readout for monitoring load

The VFD has to be wired directly to the motor, so a lot of rewiring was in order to make it work with the mill.  Before, the 220V supply could be wired directly to the mill 220V input, but now the wall 220V must split between the mill and the VFD, and the 3 phase VFD output goes back into the electrical box to go to the motor.  A few cut up extension cords later and a few more holes drilled into the electrical box and the wires were all set to go.  (Yes, everything is properly strain relieved and the wires are all the proper gauge)
The VFD: An Allen-Bradley PowerFlex4
In order to make the drum switch on the mill's front panel work with the VFD, the drum switch had to be repurposed for the VFD.  Me and Danny basically opened up the box holding the switch, did some probing, and figured out a wiring scheme that would work with the VFD.

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