Rotary Phase Converter

[addjunkie]

Thanks for all the input chaps. I have done a deal with this TOS lathe and will be collecting it on Wednesday. So it looks like a new RPC is needed. Question is what can I get for the 4KW one?

Sadly the chinese vfd has brought down the price of three phase machinery ownership, so your rotary my be a harder sell than a few years ago, but id suggest about 450 ish, think it will be a really hard sell much higher.

 

[bwservices]

3-400 but you could easily build a 7.5kw for the same price

 

[Mr-Mike]

Thanks for all the input chaps. I have done a deal with this TOS lathe and will be collecting it on Wednesday. So it looks like a new RPC is needed. Question is what can I get for the 4KW one?

Congratulations on the new lathe!

Can't really help on a price, being across the pond and such. Factors such as age and condition will play a role. Over a here decent new RPCs start around 500 - 600 USD in that size range.

Enjoy the lathe

 

[printcom]

Well new toy has arrived, now I need to sort out powering it. The way I see it I have two main choices (£40K 3 phase installation is not one of them) A rotary phase converter cira £1500 + vat or a 20hp Digital phase converter cira £2800 + vat. I have no experience with the digital phase converters but the thought of a quite workshop is very appealing. In case you are wondering the bandsaw is going, no I am not that thin

 

[maz0]

Well new toy has arrived, now I need to sort out powering it. The way I see it I have two main choices (£40K 3 phase installation is not one of them) A rotary phase converter cira £1500 + vat or a 20hp Digital phase converter cira £2800 + vat. I have no experience with the digital phase converters but the thought of a quite workshop is very appealing. In case you are wondering the bandsaw is going, no I am not that thin
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Your £1620 inc VAT for a 7.5kw RPC from http://www.hucol.co.uk/rt-rotary-converter-7-5kw

The the digital phase converter is double the money for half the functionality, I'm sure you could build an enclosure for the RPC to limit the noise.

 

[bwservices]

you could build a little house outside even,for the motor.along the lines for a compressor
tbh a rpc isn't loud enough for me to take much notice.you could stand next to mine and be on the phone

 

[Bill Edwards]

Nice sized lathe

My understanding of the ‘digital’ - ie static - converters is that they are quite limited and often best avoided if not completely unsuitable for a lot of machines.

My research into powering 3ph equipment brought the conclusion that you either use inverters which are great for some situations or a RPC for being able to plug and play anything into it. And it seems that they’re not hard to make which is what I will be doing.

As to the noise there’s plenty that could be done to reduce it.
Rubber feet for vibration, enclosing it, maybe even outside or in another area.

 

[Hopefuldave]

You could build the convertor for a lot less, I think mine (7.5 HP) came in at around £250 and some head-scratching time, possibly a fair bit less (I didn't keep track!), using a secondhand motor and a transformer converted from an old oil-cooled welder to get up to 415v. Practical Machinist has a whole sub-forum on building 'em, with an incredibly long thread on designs and calculations, might be worth a look?

Dave H. (the other one)

 

[Mr-Mike]

Wow that's a very nice little beast! A good quality RPC is pretty quiet - idler motor should produce only soft whir (below speaking volume) with properly lubed bearings and tight screws. Plus you won't need a very large one and you can place the motor remote from the panel, as eluded to by the other gents.

What I am more interested in is the floor of your shop. It's wood right? Over here we have blokes worrying about cement slabs. Do you take any precautionary measures aside from the steel plates, or is it a trivial matter in practice and not a concern?

 

[printcom]

Wow that's a very nice little beast! A good quality RPC is pretty quiet - idler motor should produce only soft whir (below speaking volume) with properly lubed bearings and tight screws. Plus you won't need a very large one and you can place the motor remote from the panel, as eluded to by the other gents.

What I am more interested in is the floor of your shop. It's wood right? Over here we have blokes worrying about cement slabs. Do you take any precautionary measures aside from the steel plates, or is it a trivial matter in practice and not a concern?

Looks like I am back to photo taking school Nope it's not wood, 8" thick concrete slab. But I will admit the finish could have been better......

I will probably go down the RPC route mainly due to price and the fact I understand just what I am getting and I have noticed that transwave does a remote control for remote siteing. As for the Digital Phase converters this was the one I referred to https://www.ebay.co.uk/itm/20HP-220...HE-MILL-SAW-/382789361693?hash=item592006201d

 

[Mr-Mike]

You know I pondered a long time deciding whether I should embarrass myself and ask if it is wood. Experience suggested it wasn't what it looked like but I need to be sure I wasn't missing something. Anyway, that is one damn thick slab!

You will be glad you went with the remote. I was able to mount the panel right above my machines. The idler is in a separate storage area on the other side of a wall.

I don't know much about the digital stuff either. Static phase converters are a sacrifice, cheap being the only benefit. I might try to educate myself a bit on the digital stuff. VFDs also hold no appeal for me.

Good luck to you!

 

[printcom]

Why is it that every time you settle on a plan of action, sod rears its head up. I have just got the quote from western power to put an additional 100amp single phase supply in. I was expecting £2K - turns out £7K+ will be nearer the mark. I am beginning to think plan "C" might be called for. Does any one know what size generator will be needed to start a 5.5KW lathe motor? I was thinking 20KVA but my 3 phase knowledge is a bit sketchy at best.

 

[knighty]

how big is the supply you already have?

 

[printcom]

how big is the supply you already have?

100amp

 

[daleyd]

Couldn’t you just run the lathe off a vfd? Probably more work in the short term than a rotary converter (you’d have to sort out the switchgear out) but you’d get the benefit of speed control once done and your 100amp suppply should be more than adequate.

 

[Munkul]

if you're looking at spending £7k on a new wiring installation then surely it's more cost effective to buy a generator? A super silent 20-30kva one installed permenantly either outside, or inside with the exhaust piped outside... you then can look at other 3 phase tools like decent size welders etc...

 

[Mr-Mike]

Can you not wire in a sub-panel, if you are a maxed out? Or are you drawing the full 100 amps? How far away is your nearest neighbor

 

[printcom]

The problem is the plasma cutter wants 40amp, the compressor 20amp, the welders on a 63amp, and a RPC of 40amp. Now I usually work by myself so only one thing get used at the same time, but ............... and thats before her indoors has a bit for the hair dryer.

if you're looking at spending £7k on a new wiring installation then surely it's more cost effective to buy a generator? .

That's the rub, I wasn't. But your right it is looking like a generator would be the most cost effective way.

 

[Mr-Mike]

I think you will be OK with your service. Just a little mindfulness. Give it a try at least.

 

[Anguz]

Finally got to go see the motor s that I have... 18.5 KW. I have 2 available if you decide to go rotary