Transwave rotary converter + variable frequency??

[flatlineParticipant @flatline]

Good Afternoon,

I am buying a 3-phase Holbrook C-10, and shall be running it from a 240v 50Hz domestic supply.

The current plan is a Transwave MT-3-DD, to create the 3-phase to run the machine.

My question is can I introduce a variable frequency in to ‘the loop’??

The Holbrook, particularly in the higher speed ranges has quite a large jump; 1492 to 3000rpm, which I would like to be able to add some additional speed flexibility in to – if it’s possible??

I can re-wire a 13amp plug, but my electronic expertise beyond that is non-existent… although I am picking up a little..

Many thanks in advance for any advice/help… 😊🇬🇧👍

[Dave HalfordParticipant @davehalford22513]

3ph to 3ph inverters exist in industry. Price up the difference of going direct to a single phase – high v 3ph inverter.

[John HaineParticipant @johnhaine32865]

Just use a vfd rather than the Transwave.

[John Haine]

On John Haine Said:

Just use a vfd rather than the Transwave.

Only if  there are no contactors involved?

[Robert Atkinson 2Participant @robertatkinson2]

No, you cannot use a Transwave rotary converter and a VFD together. To do so is a bit pointless even if you could.
The transwave is designed to drive inductive (motor loads). The VFD input is a rectifier or solid state power factor correction circuit.
You should get a single to 3 phase VFD. If the motor can’t b connected for 240V (Delta) you will need a step up version to get full power.
Note the Transwave MT-3-DD needs 25 amps input current so you would probably have to get a dedicated 32 circuit run into your workshop if you decide to use one.

Robert.

[Clive FosterParticipant @clivefoster55965]

flatline

Best to join the Holbrook group on Groups io for experienced advice on powering the C10 from a 240 volt supply.

The excellent 2 hp (nominal) 3 speed motor fitted as standard is a notorious current hog during start up and run up. It’s suggested that considerable oversizing of a Transwave unit is needed for good results, apparently the MT4 4 kw / 5.5 hp Transwave rotary converter can struggle to bring things up to speed so a MT5 5.5 kw / 7.5 hp is the safer option.

If you do go for a Transwave unit make sure that you have a good “stiff” utility supply and decent size cabling with well made connectors. I’ve encountered set-ups where Transwave units have struggled due to limitations on the utility side. Mostly out in the county where supply is via overhead from pole mounted transformers but my own, somewhat urban area, supply was on the iffy side. The guys inspecting it were not impressed with what had been done to make my house connection. A redundant apparently still connected, open ended, lead sheathed cable ending in the vicinity of my soak away was considered somewhat dubious.

I seriously doubt that an affordable VFD would be able to cope with that motor. Whether as native variable speed drive or modified for plug and play 440 v nominal three phase as done by Drives Direct. The high part speed current demands would likely collapse the internal DC bus.

Changing the motor for something more supply friendly is generally considered impractical due to the tight integration with the three speed gearbox. I believe it has been done by replacing the whole unit with a conventional VFD driven motor to get the appropriate speed ranges and single speed countershaft to get the dive lines in the right place. Besides the mechanical changes the wiring and control surfaced had to be gutted and re-made.

Clive

[Clive FosterParticipant @clivefoster55965]

One completely off the wall solution to getting 3 phase power that cropped up on an American forum was to use a three phase output hybrid solar power inverter powered via a battery bank continuously charged from a single phase charger.

Probably makes no financial sense for domestic installation, despite a smaller inverter et al being rather less costly, unless you already have, or intend to fit, solar power with battery storage but the guy advocating it runs a commercial machine shop via a 50 Kw inverter. Probably give the UK power people conniptions tho’.

https://www.practicalmachinist.com/forum/threads/anyone-running-bigger-cncs-on-a-phase-perfect.448310/page-2 

his screen name is empower.

Quotes:-

—–

Post #29

why arent people using inverters more? you can buy a 50kw inverter for 5k. even if you dont do solar like i did, buy a 3 phase inverter and a small (~50kwh would be enough) battery with some battery chargers. the chargers will be single phase and can charge the battery bank from the grid, while the inverter pulls DC power from the battery and outputs perfect 3 phase power for you. you could EASILY do a setup like this for under 10k and not have to deal with all this nonsense i’m reading about.
then you could add solar a little bit at a time after that and slowly lower your dependence on the grid/lower your bills.

Post #31

literally just bought a second 50kw inverter to replace my 30kw.

Solar Hybrid Inverter   Model: SUN-50K-SG01HP3-EU-BM4  Power: 50KW 480V Three-Phase  $4700

20/30/50/100KWH High Voltage Cabinet Energy Storage Battery    powmr.com

^^^ battery, this is with US middle man markup, can get the same thing from the source directly and save half your money.

this is the charger i use.
https://www.powerdilong.com/collections/dilong-6-6kw-onboard-charger-obc

i’m LITERALLY doing this, not some pie in the sky shit. this actually works.

——–

Clive

 

[Robert Atkinson 2Participant @robertatkinson2]

I was not aware that the existing motor is multi-speed. From Clive’s comments it looks like it has issues.
Given the cost of a large rotary converter and the required supply I strongly suggest you consider a new modern 2HP motor and a VFD.

Robert.

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