Another 3 phase issue

transformer

rectifier

frequency

Depends on the sophistication of the vfd. I've got one working that I set up like that running my neighbours two post car lift, and for some time I had a compressor running that way (which has now been sold). If the vfd has the complex solution that you mention, it almost certainly capacitively couples the ripple to the detector, in which case disconnect the sensor !

AWEM

Reply to
Andrew Mawson
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Interesting. Whilst I had initially expected a problem running 3 phase input VFDs with single phase 415 volts, I've not experienced it with either Siemens Micromaster or KEB drives. I can't really see why a designer would monitor at the ripple on the internal DC rail. If perhaps the troughs in the ripple dropped below the minimum acceptable voltage, it would be reasonable for the drive to object.

Maybe I have just been lucky in my choice of VFDs

Bob

Reply to
Bob Minchin

You sold me a Sun 350; 360 and a HP 310 some years back, when you still had the McLaren and the PDP8 and had just got the turbine. Must be about 15 years back. Doesn't time fly when you're having fun :-)

Regards Mark Rand RTFM

Reply to
Mark Rand

The bloody great beast that I got from Brian Willis (30A, 380-650V), seems to have a switch mode power supply for the DC rail. This is probably much kinder to the mains than just slapping half a dozen rectifiers across it (assuming that there's a bit of filtration on the input). This one seems quite happy with single phase input.

Mark Rand RTFM

Reply to
Mark Rand

sold).

But all the switched mode psu I've worked on start by rectifying the mains input and producing a DC rail just like the vfd's input. No reason though that either couldn't incorporate a soft start circuit to limit the initial surge, after all it's only a Triac with a ramp input.

AWEM

Reply to
Andrew Mawson

Mark,

Must be Rugby area, yes ?. Stack of ieee hp kit running hp-ux v10 or similar iirc. The rover apu was built into a frame and was run at Popham and Bruntingthorpe for several years, but that went to a Lightning preservation group last year for (hot air) dehumidification and to drive the turbo alternator, so is still doing usefull work. The Lightning t/a set is interesting - A self contained unit, well over a hundred weight and consists of an air turbine driving a 400Hz alternator, with hydraulic / mechanical governor to the air turbine inlet guide vanes. Bloody huge, heavy bit of kit that they actually fitted into the a/c fuselage. One sometimes wonders how these a/c ever got off the ground, there was so much heavy kit inside.

So what model vax ?. Don't have much dec kit left, Have been selling my collection bit by bit for some time via Ebay, sort of passing the torch on etc.

Just to bring it back on topic: recently bought an early Boxford A on Ebay. Fairly worn but recoverable and currently in bits for cleaning, restoration and repainting. Needed for model shop type work, hence the interest in this group, which everyone says is good for machine tool type stuff...

Regards,

Chris

Reply to
ChrisQuayle

Maybe i'm doing it the hard way, but all the more recent inverters that I tried complained about phase drop and wanted a more universal solution without having to dig into the internals. Tend to pick up ind control stuff at scrapyards, so end up with a variety of inverters. Cheap, most work, a few don't, but all 3 phase input.

The only one that did work on 1 ph was an old Danfoss unit with discreet logic that I used to drive a pillar drill, but it was big - approx 18" x

12" x 9" for 2Kw o/p...

Chris

Reply to
ChrisQuayle

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