Huanyang VFD - How to get single phase outputs from VFD 3 Phase output points (U,V,W)

[AP-R*D]

I would like to get single phase outputs (at 400 Hz) from a Huanyang VFD I am about to buy (see item number 170773374641 in eBay). Problem is I cannot see a neutral wire connection. My input is normal 240V 50 Hz which I believe can be connected to any two input connection points (R,S,T)

Asoka

[RayG]

Hi Asoka,

If you want 240V ( approx) 400Hz just go between any two phases, with respect to neutral it will only be 135V ( since it's likely not a clean sine wave) more likely 115V AC ( if it's a clean sign wave) give or take....

Regards
Ray

Just a bit more information, the DC bus with 240VAC will be around 325V DC, which gives 115V RMS * 1.732 = 200V interphase voltage, IF it's a pure sine wave, some VFD's deliberately distort the sine wave to give a higher RMS.. depends....

On the other hand, I'm going to guess you are planning to power some 400Hz avionics?, those 400 Hz transformers often have 115V taps on the primary, you could connect two in series across each phase ... or why not hook up three 115V 400Hz transformers in a star configuration, you would have to set the fullscale a bit higher than 400Hz otherwise you'd be getting about 135V AC ( 235/1.732 ) across the transformer... the center star point would then be neutral... but then you wouldn't need it... :)

[eskimo]

Hi Asoka,

If you want 240V ( approx) 400Hz just go between any two phases, with respect to neutral it will only be 135V ( since it's likely not a clean sine wave) more likely 115V AC ( if it's a clean sign wave) give or take....

Regards
Ray

Just a bit more information, the DC bus with 240VAC will be around 325V DC, which gives 115V RMS * 1.732 = 200V interphase voltage, IF it's a pure sine wave, some VFD's deliberately distort the sine wave to give a higher RMS.. depends....

On the other hand, I'm going to guess you are planning to power some 400Hz avionics?, those 400 Hz transformers often have 115V taps on the primary, you could connect two in series across each phase ... or why not hook up three 115V 400Hz transformers in a star configuration, you would have to set the fullscale a bit higher than 400Hz otherwise you'd be getting about 135V AC ( 235/1.732 ) across the transformer... the center star point would then be neutral... but then you wouldn't need it... :)

smarty pants...
wish the rest of us knew what your talking about......

Seriously Ray...can one power up a 240V single phase motor by connecting it to two of the 3 phase outputs from the vsd...not that I need to or want to do it..just want to know

[AP-R*D]

Hi Asoka,

If you want 240V ( approx) 400Hz just go between any two phases, with respect to neutral it will only be 135V ( since it's likely not a clean sine wave) more likely 115V AC ( if it's a clean sign wave) give or take....

.. or why not hook up three 115V 400Hz transformers in a star configuration, you would have to set the fullscale a bit higher than 400Hz otherwise you'd be getting about 135V AC ( 235/1.732 ) across the transformer... the center star point would then be neutral... but then you wouldn't need it... :)

Two Questions Ray. On the first point can I connect one transformer across UV and another across VW, and drive both transformers at 240V ??

On the second point; I think the star configuration of three transformers would look like this. First I connect U to one transformer input connector and the other transformer input connector to (arbitarary) centre point. I repeat this procedure connecting two more transformers to V and W but with other transformer input connectors all going to my aribitarary centre point. So I have 3 wires connected to each other at this centre point, but hanging in the air (so to say) with zero net current at that point (theoretically speaking).

Do you think Huanyang VFD output will have good enough balanced voltage wave and phase patterns not to cause feed back loops through this centre point?

Asoka :U

[Crossfeed]

Use 3 isolation transformers of whatever voltage suits you then set the VFD to that voltage at 400 Hz, wire the VFD side delta. Wire the secondary whatever way suits. Delta primaries will load balance star will not without a neutral and there is a risk of saturating the core of one or two of the transformers in star if the loads on all transformers are not balanced.
Look for 208V US transformers.

Do not make any connection between supply neutral and the motor side of the VFD (don't ask me how I know this) Once you are on the other side of the isolation transformer(s) you can do whatever suits.

[RayG]

Hi Asoka,

Sounds like the avionics guess might have been right?
What's the voltage on the transformer primary?

As crossfeed said, delta would be better (if the transformer primaries are 240V) , or for that matter, what about a 3phase transformer? EDIT... sorry, that was a dumb idea, the hysteresis losses would probably overheat a 50Hz transformer if run at 400 Hz..

The Huanyang is a pretty basic drive, I'd need to check, but I don't think having unbalanced currents in the phases would trip it. Better (smarter drives) would see that as a motor fault and shut down...


Regards
Ray

PS.. This one might do the trick, http://www.ebay.com.au/itm/Ex-RAF-Aircraft-Transformer-200V-400-HZ-Three-Phase-Part-No-11AZ-8660-R3C-/130635591025?pt=UK_CPV_Aviation_SM&hash=item1e6a7ced71

[Crossfeed]

Ray there is no problem running a 50Hz 240 or 208V transformer from 400 Hz on the core side of things, the peak flux is only 1/8th of normal. The problem is that the low flux causes poor coupling between the primary and secondary making the output impedance high. Eddy current losses are related to the volts per turn which is unchanged, you could probably even use a 120V 60 Hz transformer on 240V 400Hz without sending the iron loss sky high.

Back in the days of large mainframe computers there was plenty of 400hz gear around, many of them used 400Hz 3 phase for internal power distribution, this was often supplied by a motor generator set which also had some UPS capability.
If you want a cheap source of 28V avionics 400 Hz run an automotive alternator at 2000 rpm and dial up the field until you get 28V, they produce 3 phase slightly distorted sine wave the only problem is their high output impedance which is designed in to enable them to charge 12V batteries when they may be making 120V open circuit at full field power.

[RayG]

Hi Crossfeed,

Yes that's a good point, the lower flux will make the secondary impedance higher, leading to a bigger secondary voltage drop under load.

I can remember we used to get overheating when running 50Hz transformers on 60Hz, but as you say going up to 400Hz might be ok.

The alternator idea is a good one, use the Huanyang VFD with a motor to drive an alternator... :D

I think we need a little bit more information on what Asoka has got and what he's trying to do?

Regards
Ray

[Dave J]

smarty pants...
wish the rest of us knew what your talking about......

Seriously Ray...can one power up a 240V single phase motor by connecting it to two of the 3 phase outputs from the vsd...not that I need to or want to do it..just want to know

LOL, me to. It went right over my head like a 747 plane.
Glad to see I am not the only one.

Dave

[RayG]

smarty pants...

Sheesh... tough crowd... :)

Don't know about running a single phase motor off interphase connections on a VFD? It would be interesting to try... a small shaded pole fan motor might be ok, not so sure about bigger capacitor start motors... permanent split cap motors might be worth a try too.... Give it a go and report back.... :) Might be an interesting way of getting variable speed single phase..

Regards
Ray

[neksmerj]

Asoka, I'll be the dummy and ask, why on earth would you want 240V at 400 Hz?

Ken

[Jekyll and Hyde]

Don't know about running a single phase motor off interphase connections on a VFD? It would be interesting to try... a small shaded pole fan motor might be ok, not so sure about bigger capacitor start motors...

The little cooling fan in the head of my varispeed Bridgeport clone is hooked up off two of the spindle motor feed wires, seems to be working fine still...

[AP-R*D]

Asoka, I'll be the dummy and ask, why on earth would you want 240V at 400 Hz?

Ken

Thanks all Gurus!! you have been very helpful. So I owe you all an explanation.

I am helping a friend with the validation of an invention (not allowed to talk until the Patent Office publishes the patent - may be in 18 months time; provided he decides to part with couple of thousand bucks and lodge a patent application).

Next question: why Huanyang? I approached some US manufacturers for 240V or 125V 400hz generators providing single phase. The solid state ones are the cheapest; but will cost around $2,000 (incl packaging and delivery) just for 500 watt power.

Why Woodwork Forum / Metalwork Forum: This forum seems to be the only place where I can find good advice on Huanyang.

I wish Huanyang sees the market opportunity and provide a neutral connection point on the output side for drawing single phase output at 400Hz.

Ray's idea of a star configuration of three transformers (giving around135V output each) does fit the testing/validation requirements. I should try to keep the load on the transformers all close to being equal (thanks Crossfeed).

Now, when I burn the Huanyang :doh:, who do I send the refund request to?? ha ha

Asoka

[RayG]

Hi Asoka,

Sounds like an interesting project, when you are setting it up, don't forget you can scale the output voltage by varying the frequency a bit.

Good luck with it, and let us know what it is when you get further down the track of securing the patent, of course we have all signed the non-disclosure agreement. :D

Regards
Ray

[eskimo]

Give it a go and report back.... :)

no way...i'm a chicken when it comes to volts with lots of grunt