That suds pump.

[awemawson]

Too late now if you've ordered your Transwave but others may like to know it is perfectly feasible to run a "415v in 415v out" inverter off domestic 240v mains by using a 240 volt to 415 volt transformer feeding two of the three 3 phase inputs. Internally these things take in their power source, rectify it to DC then chop it about to make 3 phase AC. Usually there is a 3 phase bridge rectifier at the input - well if only two phases are supplied you still get the DC out The only caviats are a/ derate it to 2/3rds power and b/ a small number of inverters monitor the phases and will report the loss of one phase but they are in the minority.

[John Rudd]

And on the back of what you say, a 240 3 phase in will work on household mains,in the same way.....

[hopefuldave]

Too late now if you've ordered your Transwave but others may like to know it is perfectly feasible to run a "415v in 415v out" inverter off domestic 240v mains by using a 240 volt to 415 volt transformer feeding two of the three 3 phase inputs. Internally these things take in their power source, rectify it to DC then chop it about to make 3 phase AC. Usually there is a 3 phase bridge rectifier at the input - well if only two phases are supplied you still get the DC out The only caviats are a/ derate it to 2/3rds power and b/ a small number of inverters monitor the phases and will report the loss of one phase but they are in the minority.

Even easier, older inverters (ABB ACS300 series, for example) have two banks of reservoir capacitors, a little rewiring to put the neutral between the banks and live to two of the rectifier's three phase inputs and it thinks it has 480v in when you feed it 240... Again, derating by about a third is in order!

[John Rudd]

Sounds like a good idea but remember the switchers are rated for a standard 240 ac in.......so they're likely to have a Vce of around 600V.....so sticking more than 340v up them may not be liked.......

[philf]

Even easier, older inverters (ABB ACS300 series, for example) have two banks of reservoir capacitors, a little rewiring to put the neutral between the banks and live to two of the rectifier's three phase inputs and it thinks it has 480v in when you feed it 240... Again, derating by about a third is in order!

Hopefuldave,

I just happen to have two ACS300 inverters sat doing nothing for the very reason that they wouldn't run from 240V! I tried them with a transformer and they worked OK but I didn't have a big enough transformer to be able to use them on anything useful.

Do you have any pictures of the necessary mods?

 

A Hopeful Phil.

[hopefuldave]

Funnily enough Phil, I think I do... I'll try to dig 'em out, but it's not that hard to work out - when you take the cover off check for a set of 4 big reservoir capacitors (if your VFD is the same as or similar to mine, they're under the main (not the upper logic) board on the lower left, it's fairly obvious which are their leads coming through to the solder side), they're arranged as two parallel pairs in series with a PCB trace where the pairs are seriesed (is that a word?), there are two fairly hefty bleed resistors which also join on the trace you're looking for, you should be able to spot where the capacitor leads come through the board - this is where you want to put the neutral lead, I put a small brass bolt and nut through the PCB (had to drill a hole!) and soldered both sides, then soldered a 1/4" blade (Lucar) connector to the sticking-up bolt to take a crimp connector. The live i brought into L1 (I think) and then jumpered to L2 to give the rectifier an easier time.

If you're not 110% with electronics, find a radio ham / hobbyist to at least advise, you'll be creating some serious voltages in there! This is a simple voltage doubler - the full mains voltage is applied to the two banks alternately so the pair of banks charge to double the RMS voltage (about 480v under full load) or maximum to double the peak voltage (getting on for 700v) under no-load conditions. Fortunately the ACS300 series (those I've seen) have a delay circuit that puts a limiting resistor in series with the supply until the caps are charged to close to their running voltage, so there shouldn't be a big surge on switch-on.

The ripple current on the caps is increased quite a bit so the reservoir caps may not last as long as intended - if you start seeing undervoltage trips at full load it may be time to replace 'em! Also, if the VFD hasn't been in service/powered for Quite Some Time it's worth wiring a 100W bulb in series with the live and allowing the caps to re-form, or even better to slowly (stages over 1/2 hour or so) raise the applied volltage, using a Variac or similar starting at e.g. 90 volts without the motor load attached.

The one I'm using at the moment is the ACS301-4P9, which is rated as a 5HP VFD so plenty for my 3HP motor, which ABBs do you have?

[awemawson]

Dave any chance of a simple before and after sketch of that bit of the circuit diagram?

I assume it's forming a single stage Cockroft Walton doubler ?

[philf]

Hi Dave,

This is a photo of the main board in one of mine:



I have an ACS 301-4PI-3 and an ACS 311-4PI-3.

I'm reasonable with electronics (I wouldn't rate myself at 110%) but can follow circuit diagrams.

Neither have been powered up for years. I have a big variac so will power them up slowly as you suggest but I'll wait until after I've drilled any holes and done any soldering. (I've been "stung" by a capacitor before and don't want to do it again. It was in a compact camera I was looking at for a colleague and I managed to short out the flash cap with my finger. I flung the camera across the workshop and ended up with two deep holes burnt into my finger.)

Cheers.

Phil.

[John Stevenson]

Been asked to pass this message on from Ian Holdsworth AKA 'Circlip@

Sorry it's a bit convoluted but can you get a message to David D on MM forum posting of "That suds pump" to make sure that he actually has got a three phase motor on his EMCO milling head! Trouble is, although the lathe may be three phase the Head may not be, Emco drawing is a bit obscure, I often wondered if they used the same motor for both variants but just added a start Cap. for the single phase. Problem is, for both types the wiring digriam shows a STAR connection motor. Other problem is, if he puts 415 across it and it is single , the bang means a rewind as gen motors are like hens teeth and the motor is part of the construction.

[DavidA]

John,

I think he means me , David A.

Pass on my thanks to Ian in case he doesn't see this.

I agree the wiring details for the Emco attachment are a bit obscure in the Denford manual.

I'll re check everything but I'm fairly sure the plate says 415 volt.

It is connected to the lathe via a dedicated socket on the cabinet. And as the lathe is 415 Volt  3 phase I suspect that the attachment would be the same.

Dave.

[DavidA]

..I'll re check everything but I'm fairly sure the plate says 415 volt...

On checking I find that there is no plate on the unit.  So I must have been thinking about a different machine.

There appears to have been a variety of different motors fitted to the various versions.

So I'll settle for using the original connection to the Lathe..

I can confirm that it does indeed weight around 43 Kilo (as stated in the handbook). Hence the need for a block and tackle to remove it.

Dave.

[hopefuldave]

Phil, that looks very similar to what's in mine! At the top of the pic the four large ceramic resistors are the bleeds across the reservoir caps, you should just about see those below that board. You can probably buzz out to find the track which all four bleed resistors connect to and verify that it connects dead-short to all four reservoir capacitors - this is where your neutral wants to go (I managed to do it, just, without unsoldering the caps), I think I used a 6BA x 1/2" cheesehead through the board and brass nut, cleaned and polished before I started, proper tin-lead solder, of course! Onto the spare 1/4" or so of thread sticking up (on the side visible in your pic) I crimped then soldered  a male blade/Lucas (tinned brass) to take the roving Neutral. That's about all it needs to fool it into thinking it's being fed 415+ volts :-)
It does, of course, invalidate all warranties,  approvals and certifications, probably responsible for climate change, economic collapse and the English cricket team's appalling performance in the Test series too!

[philf]

Thanks Dave,

I'll have a go when I get a spare hour or so. I'll let you know how I get on.

Cheers

Phil.

[philf]

It does, of course, invalidate all warranties,  approvals and certifications, probably responsible for climate change, economic collapse and the English cricket team's appalling performance in the Test series too!

Dave,

So far so good. There were 4 pads with through holes on the top of the board available so I used them and ran 4 silicone insulated wires to the neutral.

Much to my surprise the display switched on and the fan started running at only 120v input but at 190v a relay pulled in so I guess it may have worked at that.

I smelt something like a capacitor frying so switched off. It was actually my variac which hasn't been powered up for years - must need a clean.

I'll try to connect a motor up tomorrow night. If it works OK it will go on my Fobco 7/8 bench drill.

I can't get my head round how connecting the live to 2 of the inputs helps.

You misjudged the England cricket team - thankfully!

Cheers

Phil.

[hopefuldave]

So far so good indeed! And the fastest Century on record, I sorely underestimated them :S

Using two of the Live inputs is just to give the rectifier an easier time - the current will (approximately, assuming good matching of the diodes in it) share the mains current.

Glad it seems to work, have you got the programming manual for the ACS300? I have a .pdf copy I can email if you need it...

Cheers,
Dave H. (the other one)

[philf]

So far so good indeed! And the fastest Century on record, I sorely underestimated them :S

Using two of the Live inputs is just to give the rectifier an easier time - the current will (approximately, assuming good matching of the diodes in it) share the mains current.

Glad it seems to work, have you got the programming manual for the ACS300? I have a .pdf copy I can email if you need it...

Cheers,
Dave H. (the other one)

Hi again Dave,

I've just tried the inverter (without Variac) on a 1/2 hp motor wired star. It worked perfectly!

Next job is to rewire the drill motor to star and try it on that. It's currently driven by a 3 phase input 220v Panasonic inverter (which came out of a Japanese piece of equipment) but I couldn't find a manual for it and I can't suss the parameters. I can only run it on one pair of pulleys.

I do have a PDF of the ACS300 manual thanks.

The minimum current setting on the ACS300 is 3.1a which is higher than I need but the motor will only take as much current as it needs.

Many thanks.

Cheers

Phil.