converting to 3 phase

[Random Orbital Bob]

for arguments sake....suppose I wanted to get 3 phase in my workshop. Whats the fast and cheapest route please?

 

[wizard]

What is it you want two run

 

[dickm]

for arguments sake....suppose I wanted to get 3 phase in my workshop. Whats the fast and cheapest route please?

From what I've heard, there isn't one . Especially if you live anywhere inaccessible.....
Problem is that even if there are 3 phases available in your road (which is not always the case) they belong to the transmission company and the barstewards can charge what they want to connect you.

Unless, of course, you are the fairground operators who used to bring a fair to park on the green opposite our then house. They just shinned up the nearest pole with big crocodile clips.....

 

[wallace]

Do you mean proper 3 phase or some thing to change single to 3 phase. If its for one machine and you don't intend to get more 3 phase stuff then I would say a VFD if you want more 3 phase machine then you could go down the static/rotary converter route. With a static you loose some of the driven motor's power, about a third. Rotary are better.
HTH

 

[Random Orbital Bob]

I'm upgrading my bandsaw and the older startrites are part of my scope. Many are 3 phase so this is more about a specific machine than converting the entire workshop.

 

[deema]

For a bandsaw I would use an inverter. For the size of motor you will have in a Startrite they are relatively cheap compared to the other options. The bid advantage you will the have with this method is that you get breaking to make it regs compliant and variable speed. For a simple motor application such as this you can use them straight out of the box, nor special programming required.

 

[beech1948]

I had 3phase installed in a v.large double garage. Purpose was to run 3phase woodwork machines.

I installed a 3ph mains connection box externally, an internal distribution box and temporarily a single 3 ph socket. Cost was £580.

I dug a trench from my garage to the 3ph supply cables under the pavement outside my gate about 20ft. Cost Free
I obtained permission from the electrikery board Cost £35 for the application
I called the electricity board who came and connected my cables upto a splice in the 3ph supply. Cost £2150
Testing of supply and certificate Cost £290

I back filled the trench. Cost free

I added 5 new 3ph sockets £341
Test and certificate from local sparks (with 3ph cert for himself) Cost: £150 for 21 minutes.

So it was not cheap

However, 3ph machines were very cheap then and I bought very cheaply and restored most of them. I think I saved at least the cost of the 3ph so it sort of broke even for very superior kit.

Worked in my garage for 14yrs then moved house.

Now I have sold off some machines and use 3 VFD's and a home built RPC rated at 10hp.

Hope this helps.

Alan

 

[Random Orbital Bob]

Very useful Alan......many thanks (I live in Eversley down the road from you by the way). I suspected the cost would be high...you've clarified that for me in detail.

 

[Random Orbital Bob]

For a bandsaw I would use an inverter. For the size of motor you will have in a Startrite they are relatively cheap compared to the other options. The bid advantage you will the have with this method is that you get breaking to make it regs compliant and variable speed. For a simple motor application such as this you can use them straight out of the box, nor special programming required.

It looks like this would be the simplest and cheapest option though I know inverters aren't inexpensive in their own right. Hey ho. Thanks Deema.

 

[beech1948]

Bob,

I use VFD's up to about 2hp above this I use my RPC. I built this some 3yrs ago from plans off the internet. Barriers to this were:-

a) Despite my uncertainties, and with some electronics experience, I was uncertain about how to lay this out..that is the physical positioning of the bits....so much internet research was needed.

b) The design is simple compared to complex electronics and that threw me a bit also...what just switches and relays...ha!!

My RPC serves usually a max of 2 machines at a time. You need to add up the horsepower of the machines it will run at any one time and add at least 50%. Mine are 2x3hp so need 9hp and the extra 1hp in the RPC was just a safety margin. Works well.

I have 3 machines to use the RPC with so plug/unplug can become a bit of a bother in a pro shop but I'm now a hobbyist and you could have 2xRPC of course. They are costly to buy but cheap to make.

Alan

 

[deema]

I am rather a fan in inverters compared to Rotary phase Converters for small shops / hobby for the following reasons.
1. They provide breaking to make the machine regs compliant / safer
2. You don't always know how many machines you will buy, and you always upgrade when pennies allow once you have the bug! Specifying the correct size RPC is difficult, and you tend to over specify paying a major premium.
3. The start up of a motor is where the major current is drawn. (And the lights dim!) An inverter regulates the initial surge and this allows far cheaper wiring (it's not the continuous current rating it's the initial voltage drop with high currents that forces larger diameter wires).
4. You can get very nice inverters that can be located inside the machine, and don't spoil the looks.
5. A well done converted machine is readily sellable and a single phase machine is always worth more than a 3 phase machine.
6. The power consumption is lower than using a RPC, and you don't have the constant noise of the slave motor running all of the time.

But, I'm biased!

 

[Random Orbital Bob]

wow...deema and Beech...thanks both.

 

[tool-me-up]

I use a very similar model to these http://www.inverterdrive.com/group/...r-SSD-650-015-230-F-00-DISP-UK-0-0-Eurotherm/ it is same brand etc just a slightly smaller version.
If you have a 24v dc convertor you can add jog modes, reverse direction, emergency brake and stop start and pause function to the motor. Also you can dd in potentiometer to have adjustable speed from the machine rather than the unit.

If you mount the units very close to each machine most of these functions will be useless as it just as easy to lean over and press up or down on the control panel.

 

[MMUK]

From experience I can safely say that you won't go far wrong with an ABB inverter. Maybe a little more than the Eurotherm Invensys or Siemens equivalents but much more reliable.