New address, no 3 phase supply and may be very expensive to have one

I am a one man band. I now have a rural base and there is 3 phase nearby but bringing it 100 yards to my property will be mid four figures. The standing tariff is twice the existing and kWh rate 20% higher. The existing 1 phase 230 supply is rated 18kW.
There are 20 motors between all of the machines, 2 of them are dual speed, 1 is an Arboga Dahlander, the other as yet unconfirmed in a Kearns baby HBM.
With only 2 hands there will only be one machine in operation, productivity is unimportant.
The mill is the most powerful at about 5HP including table drive. The mill and a J&S 540 have 4 motors each. Everything else 2 or 1 each.
I have access to Siemens drives for extremely cheap but the thought of fitting a score of drives seems a waste and I would rather have the full fat as I enjoy seeing smoke.
I have been reading on this subject for days and got nowhere fast. I am hoping a single phase transformer upstream of a 15HP 3 phase VFD fitted to a cart to be wheeled to the machines might be a solution.
I see no consensus anywhere on powering coolant pumps or actuating table drives with spindle motor in operation fed by VFD. I have no use for speed control other than a soft start for the spindles (trying to avoid tripping breakers.
The English guy who sells modified Teco drives insists his wares will tolerate in use switching of auxiliary motors. The largest capacity he offers is claimed to be 5HP, no overhead there. My job in digital electronics did not prepare me for this and my knowledge is found wanting.
There will be no rotary phase convertor, I will take up woodworking before that happens.
Your suggestions, proven solutions are very much appreciated!

My situation is sort-of similar. I have 2 cnc machines that are 3ph with no options. Of the smaller machines I have put some vfd's on them and run them off 1ph but it is a pain. I bought an American Rotary phase converter (30hp in my case) and used it to feed a small 3ph panel. Then I did a few 20a circuits out of that for the small machines (multiple machines off same breaker). The CNC machines got their own breaker. I think this is a good way to go. Buying a Phase Perfect to feed the panel would be better but more expensive. I got a small 3ph panel on ebay cheap, breakers on ebay cheap.

IanX

I guess Drives Direct are the folk you refer to as offering the Teco VFD units converted to give 415 volts output from 220 input. If you look on their E-Bay shop they offers them up to 20 HP.

I have one of their 10 HP units running my workshop. Its about 12 years old now and still works fine. Largest motor on my machines is a wartime built 3 HP two speed device, not the most inverter friendly of machines but the box copes fine. I have a sine wave filter unit on the inverter output and the neutral wire is connected. Which may or may not help but my, limited, electronics experience implies that this could be a better way to go rather than simply connecting the three hot wires to the machine control. Other motors are more modern 3, 2 and 1 hp on various machines. Nearest one to giving trouble is the 3 HP one on my Smart & Brown 1024 lathe which prefers a definite push - count one two - release technique on the start button. Quick touch sometimes sets the contactors chattering. Probably due to the lathe being direct drive with no clutch so motor has to start-up under load drawing bit more current. Never happens if something else is running, usually the Hydrovane compressor, at start up tho'. Not having a clutch on my main lathe means my box sees a lot of hard switching start - stop cycles.

Drives Direct data claims that VFD box should be around three times the size of the largest motor if used as a three phase substitute in Plug & Play mode. Seems about right to me. Critical issue seems to be start up draw of the first, or only, motor switched on. Often wondered if something clever and electronic could be arranged to let the VFD run up from zero as normal for the first motor whilst permitting hard switching of any subsequent motors.

Even when using conventional single VFD per motor/machine running smaller motors, for coolant pumps et al, hard switched off the same VFD as the main spindle motor is said not to be a worry so long as the main motor is running and the overload capacity is sufficient to start the smaller motors. If you can tolerate spool down rather than hard off I'd be inclined to look at a one VFD per machine solution for the larger loads backed up by a whole shop VFD for doing the smaller stuff. Should be able to use the one VFD per machine one(s) in the normal start slow and run up to speed fashion avoiding need for an oversize unit.

Clive

Some makers claim horrible things happen with post VFD switching, others do not. Having designed a number of VFDs, I can say that there is no inherent reason why switching off or on SHOULD cause a problem, so long as the inrush is within the capability of the VFD. The inrush is the main problem.

A secondary problem is "spike voltages". The VFD HAS TO have the capability to handle high frequency spike voltages just to run at all. A VFD makes thousands of pulses per second, and each pulse turns "off" in fractional microseconds, producing a large "spike" of voltage. The VFD must handle that.

In some cases, especially with long wiring runs from the VFD to the load, there may be enough of a problem that an added filter on the VFD may be good. You may need that just to stay within legal limits for radio interference, so it may already be present.

Sizing for inrush depends a little on the VFD. Some are rated 50% current for a short time, between 30 sec and a couple minutes, perhaps. Others have that PLUS a 10 second or so rating at 200% current. They also vary in their response to an overload. Some quit and throw an error code, while others can be set up to cut back current and keep running.

Motors vary, "usually" having an inrush of up to 6x the normal full load current. Odd ones may be up to 8 or even 10 times full load current, although that is relatively rare. In the US, there is a code letter to allow you to determine the inrush, I have no idea what is or has been required in Europe.

Given a motor with 6X current as inrush, and a 150% overload capability, one could rate the VFD for 4x ful load and it theoretically would be OK. I would put in an extra as a cushion, and rate the VFD for at least 6x the full load, using the 150% to cover unknowns, other loads that might be on, etc.

With a VFD having a 200% short term rating, I would be OK rating for 4x full load, uprating for any added motors that might be on at the same time (coolant, feed, etc).

To do your sizing, you need to add up the currents of all the motors in the shop that could be "on" at once. Then verify you have enough margin of current to stat the largest motor while runningas many other motors as may be "on" at the same time.

If you pass that, you an run the whole shop off one large VFD.

VFDs are not immortal.... so if you do not want to keep a spare large VFD (and there are technical reasons not to), then one VFD per machine makes sense. That way everything will not be "down" at once due to a VFD failure.

JST said:

Having designed a number of VFDs,

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Hardware, software, and circuit board layout?

JST said:

VFDs are not immortal.... so if you do not want to keep a spare large VFD (and there are technical reasons not to), then one VFD per machine makes sense. That way everything will not be "down" at once due to a VFD failure.

Click to expand...

Indeed! I found a long stored (very long stored) socket 486 motherboard and powered it up, several of the caps popped.

Clive603 said:

IanX
I guess Drives Direct are the folk you refer to as offering the Teco VFD units converted to give 415 volts output from 220 input.Clive

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Clive, yes it is they I refer to. I presume there is a voltage doubler circuit added by them at the input side.

IanX said:

snip
There will be no rotary phase convertor, I will take up woodworking before that happens.
snip

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Just curious why your aversion to RPCs?

IMHO, an RPC would be a reasonable option in the circumstances you described (one man, multiple/range of loads, VS not required).

IanX

I think they just re-configure the input rectifier and DC storage capacitor bank into voltage doubling form. Which sounds easy enough although I'm sure there are a few little tweaks and gotchas along the way if you want a reliable result. Few years back there were several folk offering similar VFD units on E-Bay converted from used ex-industrial. Supplies seem to have dried up now. Not sure why.

Drifting off topic a bit. More the sort of thing JST understands really.

Actually I don't really understand why 220 in 415 out isn't offered as a standard configuration by the manufacturer. The output side doesn't care. Still 220 volts phase to phase whether delta (low voltage) or star connection. Input side is just selection of suitably rated components. In fact my first exposure to the mysteries of VFD design, a project article by B.Yahya in Elektor magazine issues for December 1994 and January 1995, was of voltage doubling configuration. Only immediately obvious limitation is that it reduces the headroom for voltage boost limiting the manipulations available to maintain torque as you vary motor speed from its design value.

As JST says there are no intrinsic reasons why a VFD cannot be made hard switching tolerant so long as its sufficiently over-rated and given appropriate overload capacity. However its an awfully uncontrolled thing as you don't know what folk will hang on the output or what sort of loads the motor will see. Which is why with a conventional VFD as a base you end up with 3 or 4 times oversize and a correspondingly uncompetitive price tag. Conventional way is far easier because the VFD controls pretty much everything at start up. So if the motor is overloaded and stalls out rather than run up to speed on what the VFD is prepared to deliver its easy to make things alarm out. Fact is if you could be sure that the VFD would only see loads safe for normal run up hard switching tolerance doesn't need stupid amounts of overcapacity or massively greater prices. But out in the real world enough folk would hang them onto unsuitable loads, popping them in short order, to generate a reputation for massive unreliability. No sane firm will risk that.

With modern embedded processor capability it probably is possible to make an intrinsically overload safe hard switching VFD device with only modest over-rating. An extension of self setting vector drive methods should do it. Much more complex calculations tho'. Start up torque will suffer and safe variable frequency range will be limited but it could be done.

I imagine Tesla et al have taken a good look at the problem in so far as it affects their plans for widely deployed battery back up systems. Again no established maker would dare introduce such a thing as too many folk would assume that all VFD's are like that. Cue much magic smoke escape. Tesla could probably just drop the VFD side entirely and sell a range of X hp magic bricks 220 single phase in, whether mains or battery back up, and 440 three phase out ready to plug in. Doubt if the established folk could, or would. Actually I guess Tesla would probably prefer to sell you a single phase input - three phase output back-up battery system! And a roof full of solar tiles.

Clive.

RPCs are an appropriate solution if the machines are not allergic to them (some CNC is). At larger powers, slower motors are easier to find, so the noise aspect with a screaming high speed unit is less of an issue.

rons said:

Hardware, software, and circuit board layout?

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All hardware, packaging, thermal, EMI, a little circuit board, and some software. We had a software engineer, so he did a good bit of the software while I was working on other things.

Ah! It's the sound. A friend has one in his woodworking shop and I prefer the sounds from his spindle moulder and saws to the converter. I don't know what it is considering it is just another motor. So if I was to abandon machine tools I would probably have to stick to hand brace, mallets and bow saw!

JST said:

At larger powers, slower motors are easier to find, so the noise aspect with a screaming high speed unit is less of an issue.

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I just managed to delete my reply while trying to edit with a possible candidate for a slower motor, never post on forums with a phone!
I think I probably mentioned my reply to extropic regarding my disdain for RPC, the sound. My friends woodshop RPC, it does whine. I admit to never having looked at the motor plate. Its fairly small, perhaps 7kW, perhaps it is a 2800 rpm motor? I need to ask him.
I dare not say how much time I have put into this without a decision and must be thankful for small mercies that I am conducting my enquiry in my native language.
I'm hoping to have found a solution before I return home to the sticks in August, possibly with said solution or the components for it in the back of my car.
Anyhow, this motor is the first thing I fished out as a low speed candidate.
TECA2-132M2-6-B3
TEC Electric - 5.5kW 3ph 6 Pole High Efficiency Foot Mounting (B3) 132M Frame AC Motor for 400V 3 phase supply. Inverter Rated for use with a Variable Frequency Inverter Drive or a fixed frequency mains supply at 50Hz. Fixed mains supply output: 5.5kW (7.5HP) x 960RPM at 400V x 50Hz 3ph.

just throwing my words out there,
American Rotary RPC, I have two up in the rafters on isolation pads
and rubber pads, ONLY time I can hear it is everthing,including radio,
is turned off, the coolest thing is its simple as ,well I don't know,
apple pie? anyway simple.
Matsuura CNC(31X19X24?)
16" S bend
Bport
Lagun CNC kneemil
4 headed Walker Turner drill press
Big ass 12"X2" (double end) drill/ toolbit grinder
Kalamazoo belt/disc sander.
I would buy a RPC again in a heart beat.

Just casual conversation here,my thoughts.
Best of luck ,what ever you do!!!
Gw

We first mounted the 5 hp vfd to the top of the post of the car lift it powered and the large tube shape made a great speaker and very loud...

Went to grainger and found do.e isolators on clearance so for less than 6 bucks using same mounting g holes the sound is near gone.

Proper mounting and isolation should solve most RPC noises.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

"There will be no rotary phase convertor, I will take up woodworking before that happens.
Your suggestions, proven solutions are very much appreciated! "

No rotary converter allowed, complicated setup for various machines.

Are you adverse to the turn-key solution of a Phase Perfect converter?

IanX said:

Ah! It's the sound. A friend has one in his woodworking shop and I prefer the sounds from his spindle moulder and saws to the converter. I don't know what it is considering it is just another motor. So if I was to abandon machine tools I would probably have to stick to hand brace, mallets and bow saw!

Click to expand...

RPCs are not intrinsically noisy. I suggest there's something wrong with your friends RPC or the way it's mounted.

Look for other RPC installations to expand your database beyond a sample of one.

Jim, I am not. The cost is prohibitive in Europe, it is an extra 500 on average to bring it across the Atlantic and I have not looked at the warranty support for mainland Europe. In the UK most of the farmers and garage owners who don't have 3 phase buy a Transwave which tops out at a similar Dollar/Euro/Pound per kilowatt price.

His converter runs smoothly enough but it has a pitch that I find irritating, even he does and he spends five days a week in his shop.

It is reasonably simple to build a very workable RPC. That also has the advantage that you know how to fix it if you ever DO have a problem with it.

At the simplest end of the spectrum, it is just a large motor, of 1.5 to 2 times the power of the biggest set of motors you need to run at once. You get it started with a "pony motor" or even a rope, if it is small enough, It "just works".

Past that are more complicated systems with start circuits, balance capacitors, etc. If the motor is 4 or 5x larger than the load, you do not ned any balancing, really. Look up Jim Rozen's RPC... it is about as simple as it gets.

JST said:

It is reasonably simple to build a very workable RPC. That also has the advantage that you know how to fix it if you ever DO have a problem with it.

At the simplest end of the spectrum, it is just a large motor, of 1.5 to 2 times the power of the biggest set of motors you need to run at once. You get it started with a "pony motor" or even a rope, if it is small enough, It "just works".

Past that are more complicated systems with start circuits, balance capacitors, etc. If the motor is 4 or 5x larger than the load, you do not ned any balancing, really. Look up Jim Rozen's RPC... it is about as simple as it gets.

Click to expand...

I know I'm begging to be struck by lightning but a phase perfect is probably what you need. If your honestly averse to a rotary
the PP would be turn key - just add money and you're on the air. However if your largest motor you'll need to run is
5 hp you could probably get a roughly 10 hp idler motor and set it up like my converter, which uses a 5 hp idler. You want to
get as large an idler in relation to your load motor as this irons out a lot of the wrinkles in the end.

Biggest problem with this converter is I can forget it's running and leave it on by mistake when I'm done with it: