Recent content by Guineafowl

D777 lofted about 2.5m higher, and not much better. Discone?

Yes, I’ll get a pole to loft it higher. As I say, the broomstick (positioned lower down, as you can see) did receive the odd marine transmission from boats, and did well with the regular coastguard channel 64 weather broadcast. I’m wondering if the D777 is too narrow in range to receive the...

Would it be correct to call the D777 a vertical whip? It’s not working any better than the dipole, so do I take from both the above posts that it needs to be higher? I’m quite happy to buy a discone instead, but am surprised the D777 didn’t completely outperform my rubbish dipole. Thanks for...

I’m mainly interested in the 120 and 150 MHz ranges, for now. A Discone antenna will apparently cover more frequencies, but looks at risk of wind damage. Although the Bearcat will do 25-960 MHz, it misses out the 174-476 MHz range, for some reason.

I live about 3-4 miles from the Moray coast, elevation 24m, and within 20 miles of Inverness airport and an RAF base, so picked up a cheap secondhand Uniden Bearcat UBC360CLT scanner, capable of many frequencies between 25-960 MHz. The plan was, to see what I can pick up around 120 MHz for...

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...