Single phase or 3 phase or both?

[Some bloak]

I'm currently converting and building a new workshop in an old outbuilding. I'm buying machines as and when the right ones present themselves. I've already got a Sedgwick morticer, a DeWalt RAS both single phase plus a Wadkin Planer/ thicknesser which is 3 phase. I'll probably buy a new bandsaw which is available in single phase too. A table saw, preferably Wadkin AGS 10 will probably also be 3 phase when I find one.

So in the end I'll probably end up with the P/T and a table saw when found running of a phase converter- digital rather than rotary? With All other kit being single phase. I have to run new power supply anyway so all's to be had at this stage.

Does anyone see any problems with the 'mix and match' approach with power supply or will I encounter problems. I have a limited knowledge of 3 phase but I gather that the start up demand is less than single phase. Apart from that, if items of equipment are available in single phase then why not have a predominantly single phase approach with just a phase converter for the couple of items mentioned.

I must add, that my workshop will be a hobby/part time trade initially. I also live in a rural area so no three phase is available locally (if that's what or how you hook up to it if you want total 3 phase).

Any thoughts, potential problems or opinions greatly valued as always, many thanks.

 

[wallace]

There may be issues with the 3 phase machines you wish to use depending if the motors are dual voltage or not. Some are 220/440v which is what you want idealy. Then digital changers are not too expensive. The problem comes when you have a machine that is just 440v and you want to run it using a digital drive. Then they become very pricey because they are changing from single to 3 phase and from 240v to 440v.
I have lots of 3 phase machines all being ran from a 3 phase distribution panel fed from a static converter. This is perfectly fine for most machines. I do have issues with starting my 30" bandsaw and an 18" PT, for these I have to have another motor idling to improve the 3 phase generated by the static. Obviously these two have a massive bits to get spinning.
Because I am using a static I do notice a reduction in power when doing big stuff. Statics loose about a 1/3rd of the rated hp.

 

[deema]

Three phase is simply 3 single phase supplies. So, the 400v is generated by each single phase being 120 degrees out of phase with each other. Each of the three cables is not 400v which a lot of people think is the case rather than 240v.

To answer your question, it's very easy and completely normal to have a distribution board (3ph consumer unit that holds the MCBs) that supplies both single phase and 3 phase machines. So don't worry about that.

The cost of 3ph compared to single phase is significant. You need to contrast this against either changing the motors and starters of the machines or adding inverters (my choice, very inexpensive these days and you can add speed control as well as braking to make machines regs compliant and you don't loose any power. They have to be dual voltage motors however [you can get single voltage, 400v motors either rewound or the windings modified to make them dual Voltage 400 / 240 fairly easily]). In most cases depending on what machines your going to install it will work out more cost effective to remain on 1ph.

 

[Fitzroy]

I bought a three phase old Wadkin planer and then an in-verter off of ebay. I had the issue that deema and wallace mention the motor was not a dual voltage unit so I had to open the motor up and mess about with the windings (find the star point, open it up and solder new tails on that i could take outiside the motor). It was a few hours research and reading on the internet, and pretty nervy at the time, but overall i didn't find it too much trouble.

The lovely thing about using an inverter is that it gives you great start-up control on the motor for a super soft start. If i start my dewalt PT it'll often trip the shed fuses, especially on a cold day or if I leave the thickness rollers engaged on start-up, but the Wadkin on the inverter doesn't so much as flicker the shed lights.

F.

 

[HappyHacker]

Being in a rural location does not preclude 3 phase. It all depends on how many houses are near you and where they are supplied from. It costs nothing to get a quote, I was recently quoted £500.00 for a new supply to a new house but it may be more or less depending on where the three phase is available and if it has to come overhead or underground and if you can do some of the work e.g. digging trenches, yourself.

 

[heimlaga]

Three phase wery much superrior compared to single phase when it comes to powering stationary machines. Totally beyond comparition. Easier starts. A lot more torque. Less strain on the power supply. Your neighbours lamps don't go dim when you start your planer/thicknesser.
Three phase power is 400 volt between phases and 230volt (either 240 or 220 in the old days) between phase and neutral. Hence you don't need a separate supply for single phase you just run single phase machines between phase and neutral instead of between three phases.

-A 400/680 volt motor has the adwantage that you can start it on star configuration and swith to delta configuration once stated. This is usually done using a two step drum switch. By doing this you significantly decrease the peak current during start so yo can make do with a much smaller mains supply and smaller fuses. However such a motor cannot be run on single phase.
-A 230/400 motor must be started directly with a switch which causes a jerk and a current peak. Hence such a motor of the same size requires a much bigger power supply. Peak current during start is way higher that the current at maximum load ans supply and fuses must be dimensioned according to the peak. However such a motor can be run ising a phase converter using single phase.

A three phase supply may or may not be very expensive where you live. In Finland we have three phase supplied to the mains board in every house so we have no reason to use single phase for any stationary machines but in Britain there in an extra cost involved in getting a three phase supply. The only way to know the exact cost is to ask your power supplier for a quote.
After asking for a qote you can determine whether or not a three phase mains supply is worth the cost. For an average hobby workshop I doubt so but if you intend to make money you should weigh the cost against the improved performance you get on your motors. Only yo can decide for the best route to go.

As I am fortunate to have access to three phase without additional cost all my stationary machines are three phase except a small bench grinder used only to sharpen spindle moulder knives and profile plane irons. Yopu can use both systems as you please of cause.

 

[Bod]

I'm currently converting and building a new workshop in an old outbuilding. I'm buying machines as and when the right ones present themselves. I've already got a Sedgwick morticer, a DeWalt RAS both single phase plus a Wadkin Planer/ thicknesser which is 3 phase. I'll probably buy a new bandsaw which is available in single phase too. A table saw, preferably Wadkin AGS 10 will probably also be 3 phase when I find one.

So in the end I'll probably end up with the P/T and a table saw when found running of a phase converter- digital rather than rotary? With All other kit being single phase. I have to run new power supply anyway so all's to be had at this stage.

Does anyone see any problems with the 'mix and match' approach with power supply or will I encounter problems. I have a limited knowledge of 3 phase but I gather that the start up demand is less than single phase. Apart from that, if items of equipment are available in single phase then why not have a predominantly single phase approach with just a phase converter for the couple of items mentioned.

I must add, that my workshop will be a hobby/part time trade initially. I also live in a rural area so no three phase is available locally (if that's what or how you hook up to it if you want total 3 phase).

Any thoughts, potential problems or opinions greatly valued as always, many thanks.

Before you spend any more money, check with your electric supplier, whether or not you can have a 3 phase supply.
You can easily run 1 phase, from 3 phase + earth, but 3 phase from a 1 phase supply is not easy or cheap.

Bod