Recent content by Guineafowl

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...

8 kHz Configured as per post #35, the caps are in delta and had to be replaced with 2.2 nF, as the 0.47 uF ones were tripping the VFD. Do you mean the LPF in the VFD? I haven’t been able to find that out.

As before, I can’t get triggering when zoomed in (or out). Is it better to zoom in, and keep taking single shots until a decent picture appears, or zoom out and force full memory depth of 50Mpts?

I borrowed a HV differential probe, but it’s telling the same story, ie that the filter is somehow making the waveform messier. 1. No filter, output overview: 2. Pulses (occurring at 8 kHz) have a rise time of 6.56 us: 3. + filter, output overview: 4. Pulses had an irregular appearance...

No, still glitching.

The mill motor in delta.