Recent content by Guineafowl

If in V/f mode, as you state, the VFD will automatically lower the output voltage as you drop the frequency. As far as I can see, we’re back to gently bumping the overcurrent setting up until the motor/VFD combo performs as expected.

I agree, set the motor rated voltage to what it says on the plate. For the 600 rpm mode problem (and maybe the others), It might be worth trying simple V/f mode instead of sensorless vector control. During ramp-up to speed, it will keep the V/f ratio (flux) constant and not try to be too...

As you say, the motor plate doesn’t tell you much. Is it still limited to 30 Hz speed?

I can’t open this. I’ve had a look through the manual. I assume this drive was new, and not secondhand, and for the US market, therefore settings were factory default unless changed, and configured for the 60 Hz market: - P-08: Rated current. This is a guess, and could be tuned by trial and...

If you haven’t input the number of poles (12), then the drive shouldn’t be able to display an accurate speed, so I assume the output frequency has been limited to 30 Hz in response to the near overload. I’m at a loss to explain how this would help much. For one thing, half speed would reduce fan...

You had it right here: This means a VFD should tolerate running a much smaller motor, so higher-resistance windings, than it’s configured for, making the behaviour of yours seem odd. The idler also provides some inertia, to help start loaded motors. On the ones I have, yes, for the speed...

You’re right about the megger. I’d normally do a check as a general precaution on any old motor, especially if I’ve been fiddling with the wiring. It could be that the VFD is unhappy with the windings at working voltage, for a reason undetectable with a multimeter. So the VFD is 1ph 230V in...

Re: windings, I’d be checking the insulation resistance, if you have access to a megger. Sanity check - does the VFD output voltage match the motor? It’s normally one VFD per motor, and you technically have four. The Dahlander on my 1950s spindle moulder (wood shaper) acts as two motors, being...

The four-speed motor is quite an impressive feature, given the more common pulley arrangement for speed changes. There’s a short article on Oliver’s UK arm (and another on their US metal lathes in the main archives) on this excellent site: https://www.lathes.co.uk/oliveruk/ They’re always...

I’ve just re-read the thread. Sorry, Baluncore, I missed that you’d already mentioned the compass trick. I take your point about this not being useful when each of the 6 windings aren’t separate. Each set of 6 wires comes from a series delta, and each wire is from two winding ends either at a...

I’m not sure what you’re driving at there ^. Are you trying to equate the number of stator slots with pole number? For three phase motors, the number of poles is given per phase, so a 2-pole version will have 6 poles overall. For the synchronous speed, you use the per phase (P) figure in this...

Without a current-limited supply you’d risk overheating the windings, so perhaps careful experimentation with a 12V automotive bulb in series? Sorry, I can’t find the video. This chap was configuring a 415V Dahlander to accept 240V by changing the series delta to parallel. He used the compass...

If it’s any help, it looks like your two Dahlanders are: 1. 3600-1800 switching 2 to 4-pole 2. 1200-600 switching 6 to 12-pole. I’ve also seen someone using a DC power supply to inject controlled current into winding ends, watching the behaviour of a compass needle to check the phasing is correct.

Isn’t the full-load rms current of 3.12 A a consequence of the effective, or apparent, impedance under these conditions? As far as I can find out from motor control technical articles, this is the figure used to derive the 3% or 5% reactor impedance target. To add to that, the...

Looking at this another way, this link: https://vfds.com/blog/how-do-you-size-a-line-reactor/ suggests the standard for VFD load reactors is 3% of the motor’s impedance. This motor was originally plated for 400/440 V, 50 Hz, 1.8 A. Taking 415V as a common figure in that range, when I extracted...