Mark,

Only if the switch gear has overload cutouts and they operate correctly with the waveforms from the VFD neither of which is a given.
The machine switchgear does not protect the drive.
The REO filters you linked to are quite nice but they are not low cost. Did you buy a new one for a hobby installation?
Additionally the VFD may not like having a resonant filter on it's output loaded or otherwise. The smaller REO filters likely to be used in a home workshop are resonant at about 2.5 kHz so the PWM frequency needs to be a fair bit higher than this e.g. >4 kHz. Newer drives are probably OK but be sure to check that your drive is suitable for use with a filter.
I'm not that out of date. Part of my day job today involved similar issues with a multi kilowatt 3 phase converter…..

Robert .

Edited By Robert Atkinson 2 on 14/01/2022 21:17:09

The drive self protection only works for the conditions the drive is designed for. For most VFDs this does not include connecting or disconnecting the load with the VFD output energised.
It might work but that does not mean it's right.

I'm against assumptions.

Best not to generalise: if the output of a VFD has to be switched, Read The Flipping Manual! All will be well if the maker says it's allowed, otherwise…

Within my limited experience, which is only of low-end VFDs, the Manuals all forbid switching the output. I'm fully aware better units are available but so far as I've researched, they're all pricey.

Dave

Seems better to keep them all three phase, as they were built. Once you've sorted out the 3ph supply, it's done for all the machines you've got or might get,

I know in my case changing the motors would involve 11 motors, sime of which have got rather specific mounting arrangements and are of sizes no-longer manufactured. The amount of cost and work involved would be far greater than that involved in getting a 'digital phase converter' or even getting Western Power Distriibution* to put in three phase from the street.

*Other distribution network operators are available.

You need to know WHY it has neutral and what it is being used for – control circuits ? Then you need to know at what voltage. I take it you have not operated this ramp yet ? Tell us more . Noel.

VFDs and DFCs are similar technology, so overlap.  Broadly though, here’s the main differences:

Both are more efficient than static and rotary converters.  The electronics are smart, which isn’t always an advantage.

VFDs are usually aimed at motors, so in addition to speed control, they provide start/stop management (ramp up and braking), max/minima settings,  pendant control, and terminals for the machine’s emergency stop etc.  NVR is built in. The host of options available make VFD manuals intimidating.  As usual with electronics, VFDs very expensive when they first appeared, now delightfully cheap!  Main restriction is they are for one motor only – wire in permanently; do not share.

DFCs are general purpose, providing 3-phase from single-phase without motor control options, but hardened to deal with mixewd loads.   They’re a good alternative to a rotary converter.  Until recently DFCs were significantly more expensive than a rotary, but I see prices have dropped.  If the market is big enough, they will drop further.   Good for powering machines that break the one VFD per motor rule – such as one fitted with a two speed motor with a single-phase coolant pump and lamp hung off the phases.  These should ‘just work’ plugged into a DFC, and two or more awkward beasts of that type can share one.

So:

• Upgrading a Myford with a 3-phase motor, best done with a VFD.  It provides NVR, emergency stop, and speed controlled forward/reverse from a pendant.  The VFD is cheaper than a DFC.  (Unless it’s a TriLeva, where speed control is provided mechanically!  Designed before VFDs existed.  )
• DFC is a better option for powering a Bridgeport with a pancake dual speed motor and mixed accessories, especially if the workshop has other 3-phase kit that don’t need speed control, such as a compressor.   They can share the DFC

Choosing between a DFC vs rotary is about cost, space and noise.   Rotary used to be cheaper than DFC, not sure that’s still true!  My workshop has no space for a rotary and the noise would be unwelcome.   Rotaries waste lots of electricity, so, if much used, an expensive to buy DFC may pay for itself.

Static converters are cheap and cheerful.  Inefficient and basic, they can be shared.  But the 3-phase is poorly balanced, so motors cannot produce full power, and some may refuse to start.   If they work, hurrah, but static converters are far from ideal.

As an aside, Clive said it was necessary to buy a VFD rated much higher than the motor.  I think this is untrue, and least in this century.  VFD’s are smart.  They work by measuring the output voltage and current and adjusting the drive such that they don’t blow themselves up.  Their electronics are sophisticated,  intrinsically “soft-start”, not like a mechanical ON/OFF switch, where a motor draws all the power it can with a wallop!    I’ve never seen a VFD manual that said ‘buy n-times bigger than the motor’.   Anyone have a reference that contradicts me?

Dave

On 13 August 2025 at 09:21 glynboy12 Said:.

[…] Is there a way I can add a neutral to my converter

It sounds a jolly-good idea from a safety point of view !

I can’t help with an answer … but I would direct you here:

https://www.boost-energy.com/about-us/

MichaelG.

On 13 August 2025 at 15:15 Michael Gilligan Said:

On 13 August 2025 at 09:21 glynboy12 Said:.

[…] Is there a way I can add a neutral to my converter

It sounds a jolly-good idea from a safety point of view !

I can’t help with an answer … but I would direct you here:

https://www.boost-energy.com/about-us/

MichaelG.

I have a secondhand 10hp Boost Energy rotary converter – the company has closed down, but for some reason haven’t taken the website down. The phone number just goes to some, slightly surprised, ordinary bloke.