Digital or Rotary phase converter

[Echo-Star]

Good evening all


With my options still open regarding workshop Electrics, or rather more to do with motor feed electricals, and I came accross this one on the bay at £695 "labled JFK Electrical NI" 5.5kw 7.5hp, input 240 volt 1 phase output 415 3 phase and I though I'd ask those good knowlegeable folk on the forum if they have came across or even used this one, and if it's upto what it claims to be, as in producing a constant 5.5kw if that is possible.

It wouldn't be the firdt time that I've bought a pig in a poke, and at the price advertised, comparable to others seems reasonable. I've also been looking on the bay at used rotary phase converter, again at 5.5kw
As I believe either one off the above would suit my needs better at this time. decision time is looming and getting ever closer, and will need to be taken soon.

My reasoning for being drawn to the above mentioned as the TS motor is 3.3kw and the threads that I've read regarding dust/chip extraction, then I'd require a further 2.2 kw to be started after the saw. which would power a reasonable CFM extraction system.


Any thoughts/input on this would be most welcome folks

Rob

​

 

[TFrench]

If I'd known where my workshop would end up when I started out I'd have bought a good big rotary. Only machine I'd want to keep a vfd on is the lathe, everything else is fine running on its designed speed. Being able to just plug in and run without having to mess with rewiring or bypassing switches is very nice!

 

[Spectric]

Rotary phase converters are old technology, these days digital phase convertors have replaced them and are the better option for getting a 400V three phase supply from a 230V single phase supply and the output power is only limited by your supply. Having used various devices on motors, some very large I would only ever use branded units and from reputable outlets, this way you know they meet all standards of safety and have not be made cheap for a quick sell. A 3.3Kw load is about 14 amps with a Pf of 1, rising to about 17 amps with a Pf of 0.85. Remember with a motor you have to supply power to the resistance as well as the reactive component. You need to provide more details as to what you wish to supply.

 

[Spectric]

If I'd known where my workshop would end up when I started out I'd have bought a good big rotary.

If your workshop is out of the way then a big genny would be the better option, no longer restricted by the supply. A timber yard up here uses a 40Kva genny because there three phase supply is not enough to run the big saw, they are out of the way.

 

[Fergie 307]

I would agree with Specric, if you go the converter route then definitely digital. Rotary converters tend to be very noisy apart from anything else.

 

[TFrench]

If your workshop is out of the way then a big genny would be the better option, no longer restricted by the supply. A timber yard up here uses a 40Kva genny because there three phase supply is not enough to run the big saw, they are out of the way.

I meant end up as in how much big 3 phase kit I'd end up with. I started out putting vfds on everything, but that gets very expensive if you use decent brand ones. Its also a lot harder to keep original switchgear, as a machinery anorak thats fairly important to me. I also have quite a few smaller 3-phase things like grinders - putting a VFD on each would be impractical. I use a static for these currently but I do have a rotary that will eventually be mounted in the roof space of my workshop which should hopefully keep the noise down.

 

[Echo-Star]

Thak you all very much for your reply's lads, So I've got to go Digital on good advice. I've been looking around for a while and "Drives Direct and JFK" seems to be the one's that predominantly keeps showing up, with DD being way more expensive. I'd require it to run #2 machines as stated, and I was thinking the 5.5kw range would run from 32A mcb type C, I've read other threads regarding DPC's and some info, though rather vague in that they have to be over sized by as much as 3x from what you intend to run, Due to start up surge, this would take that option way out my price range at this time, as I'd then require maybe 10kw from 60Amp mcb if my math is correct.

I'll keep looking and reading up oon this topic, and i'll post a couple pic's off motor plate's.


Rob

 

[Spectric]

By the sounds of it your best option long term would be to get a three phase supply to your workshop, thats what I did when down south. Ran the three phase supply into the house to the meter, then to a junction box. From here one phase and Neutral to the house distribution board, all three phases and Neutral to an isolator and then down to the distribution board in the workshop. This gave me technically 100 amps per phase which you cannot achieve from a digital or rotary phase convertor supplied by a single phase supply.

 

[noddy67]

Good evening all


With my options still open regarding workshop Electrics, or rather more to do with motor feed electricals, and I came accross this one on the bay at £695 "labled JFK Electrical NI" 5.5kw 7.5hp, input 240 volt 1 phase output 415 3 phase and I though I'd ask those good knowlegeable folk on the forum if they have came across or even used this one, and if it's upto what it claims to be, as in producing a constant 5.5kw if that is possible.

It wouldn't be the firdt time that I've bought a pig in a poke, and at the price advertised, comparable to others seems reasonable. I've also been looking on the bay at used rotary phase converter, again at 5.5kw
As I believe either one off the above would suit my needs better at this time. decision time is looming and getting ever closer, and will need to be taken soon.

My reasoning for being drawn to the above mentioned as the TS motor is 3.3kw and the threads that I've read regarding dust/chip extraction, then I'd require a further 2.2 kw to be started after the saw. which would power a reasonable CFM extraction system.


Any thoughts/input on this would be most welcome folks

Rob

​

Hi Rob. Did you ever end up putting in a phase converter? In a similar situation and looking at JFK too. Thanks

 

[Spectric]

When going down this route remember that it is a single to three phase conversion , the input supply is the limiting factor and also

 

[Sideways]

I've only wired up one JFK dpc but it seemed quite decent and has been running reliably with no complaints.
The instructions are comprehensive.
IMO, you definitely need to size up. Whatever the size of the largest motor you intend to run, buy a drive with a headline power rating two sizes larger.
All my own kit has individual UK manufactured VFD's. If I was starting from scratch it would be cheaper to invest in a big digital converter.

 

[noddy67]

Thanks for the replies chaps. Looking at possibly buying some reasonably high end (from bc a complexity standpoint) bits of three phase woodworking machinery that contain various electronics. Been told that the quality of the phase converter output needs to be very stable for these to work. Anyone had any experience of this kind of issue? The digital phase converters appropriate seem to be v expensive too.

 

[deema]

A friend installed a few months back the largest digital phase converter JFK sell (22kw) and added a sine wave filter to smooth the output for any electronics.
I’m in the process of building a new workshop and although I haven’t yet received the quote 3 phase power doesn’t seem to be as expensive as it used to be. From the 1 April you no longer pay for transformer or line upgrades. An initial quote for 3 phase to our house was £2.5K which I’m looking at for air source heat pumps which I need two 17K units

 

[Spectric]

Been told that the quality of the phase converter output needs to be very stable for these to work. Anyone had any experience of this kind of issue?

This is a much bigger problem with with phase invertors where the output waveform is not always a true sinewave and this causes issues with some electronic equipment. The phase convertor also does not stress motor windings because your motors will run at the designed frequency and you have no EMC issues.

@deema is going down the best route and that is to have a three phase supply in the first place, now you get 100 amps per phase and can run anything that you might want to run in a domestic enviroment.

 

[noddy67]

Thanks bc again chaps. Sadly my bc quite to get three phase power connected here was in excess of £500,000 which is clearly a non starter. They needed to bring it 600m underground down a couple of lanes, revamp the transformer and add another substation supposedly.

@deema if there is anyway your friend would be happy to talk on the phone to me please could you dm me and I’ll send you contact details etc.