Digital 3 phase converter

[robert-shetland]

Hi all
I am looking at three phase conversion options for my workshop I have looked at rotary converters
and I have also looked at static and digital conversion options what I'm wondering is does anyone have a digital converter from the only manufacturer that makes them. Drives Direct is the name.
If so how well does it work and what is your experience with it?
I'm looking at getting 3 phase from the grid (extremely expensive) and also looking at getting a rotary converter with digital phase balance. from the USA.
The only other option I can come up with is to design and build a digital phase converter on my own, i have a lot of experience in electrics and electronics but cant figure out exactly how the digital phase converter works. The basis of it must be a VSD with Harmonic filter in front, and Sine Wave filter on the output side. And a bank of capacitors on the output to take the start current. But apart from that im not sure what else. And those bits alone in no way could justify the cost they charge. Seeing one would help or any ideas any of you may have.

 

[m_c]

I run my workshop from a 'boost' aka 240->380V VFD, which replaced a home made rotary phase converter.

My setup is a 5KVA isolating transformer (had issues with the main feed RCD tripping, and the simpler fix was to isolate the VFD) -> 7KVA boost VFD -> Sine wave filter.
I also left the previous idler motor connected to provide a bit load for the VFD to help smooth things out, and to also provide some inertia in the system for starting bigger motors.

 

[robert-shetland]

I run my workshop from a 'boost' aka 240->380V VFD, which replaced a home made rotary phase converter.

My setup is a 5KVA isolating transformer (had issues with the main feed RCD tripping, and the simpler fix was to isolate the VFD) -> 7KVA boost VFD -> Sine wave filter.
I also left the previous idler motor connected to provide a bit load for the VFD to help smooth things out, and to also provide some inertia in the system for starting bigger motors.

So a transformer into 1 vfd then ankther? Then a sine wave filter. What do you run off that?

 

[robert-shetland]

I run my workshop from a 'boost' aka 240->380V VFD, which replaced a home made rotary phase converter.

My setup is a 5KVA isolating transformer (had issues with the main feed RCD tripping, and the simpler fix was to isolate the VFD) -> 7KVA boost VFD -> Sine wave filter.
I also left the previous idler motor connected to provide a bit load for the VFD to help smooth things out, and to also provide some inertia in the system for starting bigger motors.

I have a 480v split phase supply, so dont need the voltage doubling part, actually need to reduce the voltage, so in my case would an isolating transformer, into a 40kw vfd, then out from there to a delta to star transformer work? Reason for the delta to star transformer would be to grab a neutral from the star point?

 

[m_c]

So a transformer into 1 vfd then ankther? Then a sine wave filter. What do you run off that?

Just Tx->VFS->Sine wave filter.
I run a CNC lathe which under full load would need 7KW, but it never machines anything that stresses the spindle, and used to have an old 2HP milling machine.

I have a 480v split phase supply, so dont need the voltage doubling part, actually need to reduce the voltage, so in my case would an isolating transformer, into a 40kw vfd, then out from there to a delta to star transformer work? Reason for the delta to star transformer would be to grab a neutral from the star point?

480V supply complicates things, along with wanting 40KW.

A 40KW transformer isn't going to be cheap, and if you only have 2 phases, you're going to have to derate the VFD to allow for the increased load on the rectifier diodes used.

In terms of generating a neutral, drives direct just use a basic star point transformer setup (actually, I'm not sure you'd even call it a transformer, as it's just 3 single coils connected to provide a star point, so nothing actually gets transformed...).
One other benefit I get from leaving my idler motor connected, is it can generate a neutral, however I have never had a need to wire in the neutral (other than it got used for the up to speed control on the old rotary setup)

 

[robert-shetland]

Just Tx->VFS->Sine wave filter.
I run a CNC lathe which under full load would need 7KW, but it never machines anything that stresses the spindle, and used to have an old 2HP milling machine.

480V supply complicates things, along with wanting 40KW.

A 40KW transformer isn't going to be cheap, and if you only have 2 phases, you're going to have to derate the VFD to allow for the increased load on the rectifier diodes used.

In terms of generating a neutral, drives direct just use a basic star point transformer setup (actually, I'm not sure you'd even call it a transformer, as it's just 3 single coils connected to provide a star point, so nothing actually gets transformed...).
One other benefit I get from leaving my idler motor connected, is it can generate a neutral, however I have never had a need to wire in the neutral (other than it got used for the up to speed control on the old rotary setup)

Thanks for all that, actually a transformer i can get and a vfd for not too much though a friend. My goal is more making a 3 phase workshop supply, willing to spend a bit to make it work, just not the 35k Drives Direct are quoting.
So lets say i want 50hp max, and get a 100hp vfd, 50hp transformer and set it up like you have, would that then run what i want to, which is a 4m press brake, 105a cnc plasma and extraction, 5kw cnc router, etc etc?

 

[oilcooled :)]

Digital Phase Converter 5.5Kw/7.5Hp 240V in 400V Out - JFK Electrical

5.5 Kw / 7.5 Hp 240 Volt Digital Phase Converter Input Volts 240 Single Phase ( Supply 32Amp type C Mcb ) Output Volts 415 Volt 3 Phase ( No Neutral ) Dimensions L 280mm x W 145mm x d 180mm Weight 4.5 Kg Change your Garage/Workshop from single 240 volt to 3 phase 415 … Continue reading Digital...

www.jfkelectricalni.com

I was myself looking at one of these would it run an ironworker satisfactory or would a rotary be better?

 

[frank horton]

truly a black art.....

 

[sako243]

So lets say i want 50hp max, and get a 100hp vfd, 50hp transformer and set it up like you have, would that then run what i want to, which is a 4m press brake, 105a cnc plasma

Do you have a big enough incoming supply? 50hp is almost 40kW and at 220V is >150A.

 

[robert-shetland]

Do you have a big enough incoming supply? 50hp is almost 40kW and at 220V is >150A.

I have a 480v split phase supply at 100a, so have 48kw total. So yes 50hp should be do able.

 

[Tom O]

I have a phase perfect that works flawlessly

 

[oilcooled :)]

Digital Phase Converter 5.5Kw/7.5Hp 240V in 400V Out - JFK Electrical

5.5 Kw / 7.5 Hp 240 Volt Digital Phase Converter Input Volts 240 Single Phase ( Supply 32Amp type C Mcb ) Output Volts 415 Volt 3 Phase ( No Neutral ) Dimensions L 280mm x W 145mm x d 180mm Weight 4.5 Kg Change your Garage/Workshop from single 240 volt to 3 phase 415 … Continue reading Digital...

www.jfkelectricalni.com

See them converters say no neutral wire what kind of machinery needs a neutral ??