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Thread: Non induction motors and VFD
03-03-2011, 07:44 AM #1
Non inverter dutymotors and VFD
First post and I come a beggin'.
So I am trying to get my teco ev vfd to power the ancient motor on my shaper. I am fairly certain everything is wired up right and the settings are tuned to the motor but all I can get is a suspicious growl from the beast. The tech says no way, no how on any non inverter motor but my research turned up plenty of folks using vfd's as phase converters on old gear. Any hints on how to proceed?
03-03-2011, 08:01 AM #2
What is a non-induction motor? Without even seeing it, and unless it is powered by gasoline, compressed air, or hydraulic oil, I am pretty sure the motor on your shaper is an induction motor. Either the motor is bad, it's not wired up right, or the VFD is not tuned. As a sanity check, you should be able to start the motor with no load on single phase by using a pull rope, leaving the VFD out of the equation. That will at least indicate whether the motor is basically OK.
03-03-2011, 08:36 AM #3
I meant non inverter duty motor, not induction. Edited my post, thanks for the reply!! It looks like pulling the motor and getting it tested may be necessary.
03-03-2011, 08:53 AM #4
If it's not a 3 phase motor it won't work. Do you know anything about it? Pictures? Description of what you see?
If it looks anything like this, keep it as a museum piece. It's called a Repulsion-Induction motor and because they are physically big, people assume they are 3 phase, but they are single phase. They were very common in old farms and machine shops dating back to the turn of the century, but are essentially useless today unless you want to keep making your own wear parts.
Scale on that picture is a bit misleading, this is a 1HP 230V motor.
03-03-2011, 12:04 PM #5
The motor is origional to a vernon shaper. Three phase, 3/4 h.p., 220/440 v., 50 -60 htz. I have a 1 h.p. rated teco vfd. Dialed in the amps, took it out of vector mode, played with the acceleration... The motor is wired for 220 and i have it into to a breaker that is a bit oversized for the machine. As far as the motor condition, I have to say the machine doesn't look like its been used too much so I don't really suspect that it's bad, but ya never know. I am hoping for a quick tweak on the vfd to get it running so I don't have to wrestle that thing from underneath the cabinet!! Wishful thinking?
03-03-2011, 05:15 PM #6
So it doesn't turn at all, just growls? Bad sign. If the VFD were not set up perfectly, or even if the motor was accidentally wired for 440V it would still turn, just not optimally. Growling sounds like it's single phasing, i.e. an open winding (or connection). If it were a ground fault or phase-to-phase short, the VFD would trip out, but it doesn't know what yo do with an open circuit inside the motor or connections. Check your own connections again first, then check the motor connection box. If all the connections are good, put an ohmmeter on the motor windings. That doesn't tell you much, but it will find an open winding. Don't run the VFD again until you identify the problem, you don't want to kill that too.
And by the way, there is nothing about a "non-inverter duty" motor that would not make it run from a VFD, the issue is that an inverter will shorten the remaining life of an old motor. Not too much of an issue at 240V though, it's more worrisome at 480V. The "tech" is a noob, or someone who has been trained to try to frighten you into buying a new motor.
03-03-2011, 08:37 PM #7
I wonder if the motor has been connected for 230 V correctly or if there is an open coil. Mis-connect a lead or if one coil is open the motor will growl no matter what you hook it to.
I suggest you ring out that motor coil by coil in separate pairs of leads for continuity. Then make double sure the leads are connected correctly. Be very careful. Those old motor leads harden up and the insulation gets crumbly. It's all too easy to move a lead and the insulation simply falls off the copper.
03-11-2011, 01:22 AM #8
Got it rollin! Bad contact in the housing. I knew it would work!
The vfd works great. Anyone have a source for switches and dials? Thanks to all for the help.