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View Full Version : ALTIVAR VFD fault - is it terminal?



Timleech
10-13-2011, 03:27 PM
I was halfway through a long facing cut last night on my big lathe when the motor died, quietly & without warning. Nice easy cut, nothing stressed. It was planned to be the last cut of the day anyway.

Got time to have a proper look this afternoon, the Altivar 58 drive is showing 'Scf - short circuit fault'. Looked it up, it usually means an insulation failure on the motor. Tried disconnecting the motor & powering up the drive again. Still same fault indication, so I'm assuming it's a problem internal to the drive.
Can anyone with proper knowledge of such things advise me - is it likely to be scrap?
It's a 10hp drive running from a 3-phase rotary converter (415V 3-phase in & out), been working fine for a couple of years.
Resistance between phases of the motor is pretty much consistent at 1.3 ohms, resistance to earth is several megohms though I haven't yet tried a Megger on it.
I got this drive secondhand a number of years ago, it owes me very little, but I can't afford a new 10hp drive this week, & have to get on with the work!
Anyone in the UK know a good drive repairer, or have a 10hp drive for sale cheap?

Tim

macona
10-13-2011, 04:30 PM
Sounds like the main igbt block shorted out. You can find replacements, you will need tools to desolder and install the new one.

Hopefuldave
10-13-2011, 07:37 PM
Could be worth checking if you can clear fault codes (most VFDs keep an internal log) and try again - I'd think it might (if I had designed a VFD it would...) scan the last fault code and refuse to start up if it's a "service/safety affecting" fault like insulation breakdown - bear in mind that the peak voltage from a VFD can run to 1200V in some cases (cable impedance mismatches etc.) so a megger will show insulation faults a regular multimeter won't :(

If all else fails, where in the UK are you, I have a hefty (10 HP?) 3-phase motor suitable for a phase convertor (located Surrey/Hampshire border) that I'd part with if the price was right?

Dave H. (the other one)

macona
10-13-2011, 07:59 PM
Never seen a VFD that wont reset after a power cycle. If it is tripping with no motor connected its bad news.

MrSleepy
10-13-2011, 08:09 PM
Sounds like the main igbt block shorted out. You can find replacements, you will need tools to desolder and install the new one.

I wouldn't be suprised if Tims Altivar uses a Semikron Skiip package with integrated rectifier and bridges....All my Altivars do.

the skiip packages clamps pads on the pcb to connectors without soldering.

If it needs a new skiip module..its scrap...the cost here will be as much as a new unit.

Rob

Timleech
10-14-2011, 04:08 AM
Could be worth checking if you can clear fault codes (most VFDs keep an internal log) and try again - I'd think it might (if I had designed a VFD it would...) scan the last fault code and refuse to start up if it's a "service/safety affecting" fault like insulation breakdown - bear in mind that the peak voltage from a VFD can run to 1200V in some cases (cable impedance mismatches etc.) so a megger will show insulation faults a regular multimeter won't :(

If all else fails, where in the UK are you, I have a hefty (10 HP?) 3-phase motor suitable for a phase convertor (located Surrey/Hampshire border) that I'd part with if the price was right?

Dave H. (the other one)


Thanks for the offer. I'm already running from a phase converter (with 10hp motor), the inverter drive is there mainly to give a soft start as the lathe motor really struggles to start direct from the converter. The lathe (DSG 1910) has a lot of kit in the headstock to get into motion on startup. The variable speed is a major bonus, also the better balanced 3-phase output gives a significantly quieter headstock ;)

Tim

Timleech
10-14-2011, 08:41 AM
I've dug out an old but unused ABB 600 drive I had buried at the back of the loft, it's only 7.5 hp but it might get me out of trouble in the short term.
I also have an SSD 11kW drive, which ought to be great but the earth leakage current on that is so high that as far as I can see it's going to be unuseable on any supply derived from domestic mains. I've tried it in the past & it just trips the (not very sensitive) earth leakage breaker.

Tim

Hopefuldave
10-14-2011, 03:27 PM
Agree re soft starts, variable speed etc. - although my Holbrook's not too bad, there's a clutch (high/neutral/low speed) straight after the motor. I've hacked an older ABB 300 VFD to fool it into thinking it has 415v in so it can power the Holbrook's 3-speed 415v-only motor (with some jiggery pokery to coast the motor during speed/winding changes). The hack took all of 5 minutes with the soldering iron after 15 minutes of head-scratching - gluing the casing back together took considerably longer (thanks courier now known as "Don't Handle, Lob"...)

Thinking of variable speed, anyone else trying to hook a linear pot to the cross-slide to give "constant" surface speed? I suspect it'll need some sort of max/min function too :confused:

RE the earth leakage breaker, there are 100mA time-delay versions available - the Shed Of Danger is fed with one, though mostly to protect the SWA feed cable, as there's a 30mA RCD in the local fusebox. I had thought about feeding it all via an isolating transformer, but unless it was centre tapped (and a bit safer with only 120v to earth) I'd still want an RCD downstream of it? All null and void if I find a big enough transformer to get from 240 to 415 though!

Dave H. (the other one)

Timleech
10-14-2011, 04:13 PM
I've got the lathe rigged up now with the 7.5hp ABB drive running the 10hp motor. It all seems to work, though while I'm at it I'm trying to sort out a problem with the electric brake not working, which has bugged me for a while, so not given the lathe a proper workout yet.

The drive can be programmed for motors up to twice its rated size, I haven't yet found reference in the manual to how the drive protects itself against overload other than a thermal cutout. I'm interested to know how much chance I have of wrecking the drive this way? In reality I'm not likely to run at much above 7.5 hp for extended periods, the single phase domestic supply will be starting to groan, but it would be good to know the answer.

I've emailed Schneider to see what they say about the failed Altivar, there's reference somewhere to asking them if the SCF fault is displayed with no motor connected, I'm not holding my breath for a reply.


The supply comes from a domestic box with an 80mA earth leakage breaker, I'd really need to fit a split consumer unit to get round that which wouldn't be a five minute job (and no doubt would have to employ a qualified electrician to do it and be within the law these days!)

Thanks to all for suggestions

Tim