THREE PHASE???

[rustmagnet]

Hello everyone,
I am acquiring a Harrison M300 and now that the search is over and the beast is on the way the question of power supply, which I had put to the back of my mind, has to be addressed. I have had a word with Transwave etc. but am wondering if anyone has had any experience with rotary or static converters / inverters and this machine (or similar), and which in your experience would prove suitable (noting that the all singing all dancing 4hp rotary converter they suggest costs about £650 + vat).
Another possibility might be the swapping of the three phase motor to a single phase one but as the existing motor is 3HP (2.2KW) would it be worth it and how big would I need (I am no electrician so would probably need someone to do it and have no idea how much they would charge?)


The lathe has suds pump and light but I suppose I could not use/ change the motor on the pump.

Any help would be appreciated so don't be afraid to air your views

Many thanks

Rustmagnet

[jackrae]

Don't even consider going for a single phase motor - unless it's free and a direct fit, you WILL be disappointed. Firstly they are more expensive than their 3ph equivalent, they are larger and they produce vibration.

You have two basic problems with respect to 3ph to 1ph conversion:

1) All your control gear will probably be run from a transformer that takes its supply from the original 415 volt supply (across 2 phases) In all probability the actual controls will be either 50v or 110v. This really isn't a difficult problem to solve since you simply get a replacement transformer to power them from your 230volt 1ph supply.

2) The motor is 415volts 3ph and the solution to this problem takes two separate lines of possibility. If the motor plate shows 415 star AND 230 delta connection then you could use either an electronic or a transformer or rotary convertor. If however it is ONLY capable of rigging for 415 then you are forced to go for a transformer or rotary type convertor. If it's wired as star and you can see 6 wire ends then you can rig it for 230v with an electronic invertor.

Given the options, if you can rig it for 230 then I'd recommend you go for an electronic inverter. This is because the electronic version gives you variable speed which you WILL find wonderful. Especially so in eliminating those anoying vibration marks you sometimes get on your turning - a slight tweak in motor speed often cures them.

However if you want a simple option then go for a transformer or rotary type convertor since this will produce the fixed 415v 3ph supply that you need to directly connect the lathe as it currently stands - You shouldn't have to do any modifications to the machine wiring at all.

Getting a 3HP rotary invertor started off your household system may mean running a direct supply from your supply board since it'll need something in the order of 4KW capability to get it up and running which is too much for the conventional 13A socket.

Good luck
Jack

[3405jimmy]

I run a 5.5 kw 3ph rotary of a 32A ring in the garage. You would not know your not running off the mains. Plus its a lot cheaper than the £1200 connection charge the leccy board wanted just to connect me, trench and cable extra!

jim

[Uzzy]

I had / have this problem with my Mill and I bought an inverter on ebay a word of warning though make sure you get the right size I did not and did not get my money back selling the one bought in error. I would watch a few to see what they go for?

[chris vine]

Hi,
Does the harrison have a clutch? If not, this may be interesting for you.

I run a 3 phase mill (harrison) from a static converter. One problem I always had was that the starting torque was very poor. My mill did not have the optional clutch fitted and starting in the higher gears would stall the motor unless the machine was well warmed up.

Recently I fitted a 3 phase pilot motor, always running when the converter is switched on. This has improved things greatly. The pilot motor was free and the starting torque on the mill is much improved as the supply is much more like real 3 phase.

I suppose this is really now a rotary converter but for the same price as a static.

The pilot motor needs to be quite large, similar or even a bit bigger than the largest motor running off the converter.

Chris.

[wayne]

Have you thought of giving Harrison’s a ring (they are now called lathes 600 and are located in Heckmondwike, west Yorkshire), they may be able to tell you the frame size ect for a single phase motor, which you will need to purchase a replacement motor.

Also if you go for the single phase motor go for a capacitor start and run, as to vibration, some of the new motors on the market are terrible in either three phase or single, also 2800 rpm motors are 2 pole and 1440 are 4 pole, 4 pole motors are always smother running.

Also you can not run a 230v 2.2kw motor properly of a 13 amp supply, due to the effects of inductance and motor starting, fuses are always greater for inductive loads than the equivalent resistive load (, if you start and stop the motor frequently you will probably need at least a 20a breaker, type C if mcb consult a qualified electrician who can see your lathe and your electrical supply.

Brook Cromptons Installation guide for motors
www.brookcrompton.com/pdf-files/103efd_iom_v4.pdf
harrisons link for ifo phone numbers ect
www.600lathes.co.uk/six04.html

[rustmagnet]

Thanks for the replies,
In August I figured that whatever I was going to get it would require a bit of figuring out and to give myself as many options as possible I got my main board renewed with a split board and new 2.5mm armoured cable to my 2 sheds with a 32amp fuse. I also have a small board in the workshop shed with 2 fuses and trip.
Its fantastic that there are those out there who are willing to share their knowledge. So far it would appear single phase is a non starter and the pilot motor sounds a bit too technical .. but thanks for the insight into how clever some people can be...But don't stop now.
Rustmagnet

[wayne]

The point i was tiring to make earlier was a good quality single phase motor can be better than a cheep three phase motor, also 2.5mm radial circuits should have a breaker of 20a and for 32a breaker it should be 4mm cable.

Only a ring circuit should done at 32a with 2.5 cable. As you are in a shed, the supply to the shed should be protected by a RCD, the RCD can save you life literly, i hope by trip you mean RCD

Ps i used to work up until 12 months ago with motors fitted to the same equipment in single and three phase, and often did conversions from one to the other

[rustmagnet]

Thanks Wayne for that, I wasn't dismissing single phase out of hand, but I inspected the lathe and was astonished by how quiet and smooth it ran. I'd been prepared for the proverbial washing machine full of ball bearings. Thanks for the heads up on fuse rating (now I remember the electrician said I should change it.. believe it or not it was a M.K. Board and one 20A wouldn't stay ON and the screw for holding the 5A fuse was broken ! obviously I got a returned item) and yes I did mean RCD at 30mA.

p.s. if your'e not carefull, you might be renewing your career in Selby. ;D
cheers

[chris vine]

Hi The pilot motor really is simplicity itself. You have got the lathe and will put a plug on it to go into a static 3 phase converter.

There is usually an issue with making sure that the two wires from the lathe which power the control gear go to the two phases which are properly powered by the converter. This is in the instructions for the converter anyway.

Now just put the 3 wires from the pilot motor, say a 2 kw size, also into the plug, IE in parallel with the lathe.

Now when you switch on the converter, the first thing it will power up is the pilot motor. The lathe is connected to both the converter and the pilot and the result is that you get a much better 3 phase supplied to the lathe than just from the converter.

If you have a clutch on the lathe you probably wont need to do this anyway!!!!

Chris.

[houstonceng]

Rustmagnet

Only just seen the topic having been busy on SWAMBO's garden project.

Personally, I'd always go for the Inverter (Variable Frequency Drive) solution if you've only got one 3-phase machine to power.
1. It gives you a "soft-start"
2. It'll allow you to select most speeds without belt/gear change
3. To run a 2.2kW motor you only need a 2.2kW inverter NOT - as recommended by Transwave et al - circa 4kW of Converter to handle the surge.
4. You'll get a better 3-phase than you will from a converter - even when fitted with a pilot motor.
5. They are usually cheaper than converters - more so if bought through E-bay
6. You don't need that pilot motor.

Contrary to popular mith.
a. Single phase motors are not always larger than 3-phase of the same rating - see Brook-Crompton cats. A 1.5kW motor is frame size 90 irrespective - although I'll admit that a single-phase 1.5kW Brook-Hansen motor of 1997 vintage is frame size 100.
b. Inverters are not all 240v 1-phase in and 240v 3-phase out. There are a few that give 415v out fore 240v in - see E-bay.

The downside of the Inverter route is that you may need a new suds motor. Not always, however, since they are sometimes connected to one phase - good advice already given to contact Harrison.

Couldn't agree more about the fusing (MCB), RCDs and wire sizes. Must, however, refer you to building regulations Part P since you are required to conform with this.

A downside is that you can find that the leakage current in an Inverter/ Converter will exceed 30mA and that'll give you no end of problems with standard RCDs.

As an RCD is there to reduce the risk of electric shock should you cut through the cable, sockets in Garages and Sheds which may have, say, a lawnmower connected to them must be protected by an RCD either on the consumer unit or as individual combined RCDs and Sockets. The former is becoming "standard". My advice is to use a 32A IP44 Splashproof industrial plug/socket for your lathe - not powered via the RCD. That way you satisfy three requirements.
i. You won't trip the RCD
ii. You wont be able to connect the lawnmower to it - so no Part P infringement.
iii. It will have no problems supplying your 2.2kW load without getting hot (at a pinch a 16A IP44 would do but I like to have a little more of a safety factor)

Bottom line. There are probably as many Inverterphiles as there are Converterphiles. You pays your money and - - - -

Read up on both solutions on the Transwave, IMO, SDD, Newton-Tesla, etc, web-sites and make your choice.

Best of luck

Andy