Sedgwick TA315 - 3 phase to single phase conversion - help

[TomMowlam]

Dear all,

I'm replacing my Elektra Beckum format/dimension saw. Been offered an old (ish) but very good Sedgwick TA315. Running on 3 phase. I only have single. Several questions - below, any help with them would be appreciated. It's also completely impractical to get 3-phase at my workshop.

My workshop runs off my domestic household supply, albeit through a beefy separate circuit. I can happily run multiple machines - union grad lathe, Sedgwick planer and EB dimension saw at once without the lights flickering.

Option 1) Running a 3-phase saw through a phase inverter
Is it economic?
Would I blow my house electrics every time?
Is there a noticeable power drop?


2) Replace old 3 phase motor with single phase motor

Is it just as simple as swapping the motor and rewiring?
If so - any recommendations on a good brand of motors for saws? I need something with some oomph as I mainly cut hardwood.
Anyone know whether Sedgwick would just sell me a single phase motor?

Any help greatly appreciated.

Cheers

Tom

 

[kinsella]

Tom
One of my biggest regrets is turning down a load of 3phase gear for that exact reason. In hingsight i would either change the motor to single phase or use a belt from a single phase to turn the motor. i have a 3phase Wadkin radial arm motor rewound and it went from 3hp to under 1hp. When cutting a big section of oak i have to take my time. My opinion if its a one off bit of kit is a new single phase motor.

Some one else can help with motor as i have no idea, i would just pick one from machine mart.

 

[RobinBHM]

If it is a motor with a standard frame size, replacing may be possible -ive no idea whether these saws are belt or direct drive.

I wouldnt think going back to sedgewick would be economical, if its a std frame try motors direct in Brighton or somewhere similar. You could then get some pricing and compare with an inverter. The wiring will be different of course with a single phase motor.

 

[CHJ]

I would suggest the best option for your power supply situation would be to use a suitable Inverter to generate a three phase supply.

• 1. The machine does not have to be touched and all agro re:- finding suitable motor and pulley combination goes away.
  2. The invertor should have a soft start function and overload protection built in.

This will mean that the start up current for the band saw will be softened and supply not be subject to harsh start up current spikes.
If the band saw should jam and stall the motor the invertor should shut down.

It will also give you a very much wider speed range capability.

That's how my 1 HP Lathe works and it's running on limited supplies put in to the building in the 1960's.

 

[timber]

I would suggest the best option for your power supply situation would be to use a suitable Inverter to generate a three phase supply.

• 1. The machine does not have to be touched and all agro re:- finding suitable motor and pulley combination goes away.
  2. The invertor should have a soft start function and overload protection built in.

This will mean that the start up current for the band saw will be softened and supply not be subject to harsh start up current spikes.
If the band saw should jam and stall the motor the invertor should shut down.

It will also give you a very much wider speed range capability.

That's how my 1 HP Lathe works and it's running on limited supplies put in to the building in the 1960's.

Is the 3 ph. motor wired for star or delta and are we talking circ or band saws??????

 

[CHJ]

Is the 3 ph. motor wired for star or delta and are we talking circ or band saws??????

Yes , I should have mentioned cost factor could be significant here if it is not a dual voltage motor and needs 440 volt input. (Star (440v) Only as opposed to Star/Delta (440/240v) capability)

 

[TomMowlam]

Thanks guys. I think I'll take a punt and go down the phase inverter route. Electrics. What's the worst that could happen eh?

Just to clarify - it's a circular saw.

Thanks again.

Tom

 

[graduate_owner]

The TA315 has a 4HP 3kW motor (according to a web site I viewed) so if your existing machinery load is similar then it sounds like you should be OK regarding the electricity supply, apart from the fact that the starting current will be high, typically 5 - 7 times full load current. That could cause your mcb to trip, and if that happens then you could change the mcb for a type C which gives similar protection but will be less prone to tripping under these start up conditions. Do not be tempted to change the mcb for a higher current rating.

Personally I would stay with 3ph rather than try to change the motor because getting a suitable replacement can be a hassle. You need to consider frame size, type of mounting, shaft size, plus getting a 4hp single phase motor will not be easy. You would probably have to go down to 3hp which may be undepowered (I don't know - depends on what depth of cut you need I suppose). Alternatively sourcing a brand new 4hp motor would, I expect, cost several hundred pounds.
If you stay with 3 phase then you have 3 choices. A static 3phase converter rated at about 5.5hp should do the job. A rotary converter is dearer but more flexible with an output which is closer to real 3phase. An inverter will give you variable speed and although that is no use on a table saw, it could be useful if you decide to change, say, your lathe to 3 phase.
I just bought a British made 3hp imverter for just under £200. I would avoid Chinese ones.
If you go for an inverter then you will not be able to use the table saw's switchgear. The inverter must connect directly to the motor (unless you are prepared to spend big money for a different inverter type).

I bought a 3hp static converter for my 3hp Colchester metal lathe because I needed to keep the existing switchgear. It starts the motor but not at top speed, I suppose because of drag in the gearbox. When it's cold it won't start in the next lower speed, again I suppose because of increased drag due to cold oil being thicker. On that basis, a 4hp static or rotary converter could work on your saw because it's driven directly via a belt rather than a gearbox.

There you go - that's my opinion anyway.

K

 

[navypaul]

hi
if you haven't sorted it out already there is a retailer on ebay who does British built motors of all output and frame sizes he is local to me and we have spoken in depth about many motor based topics he knows what he is on about

http://www.ebay.co.uk/itm/Electric-Moto ... xyRhBS9MIV

this could be what you need and its pretty cheap too plus you get a new motor

paul

 

[thomsj]

Hi to all
I've just joined UKW so please be gentle. I'm fairly new to woodworking and have recently purchased a Sedgwick TA315 and in the process of converting from three to single phase. Let me start by saying Sedgwick quoted nearly £1300 for the parts to do this.
After extensive motor research I found it impossible to find a 3kW single phase motor that would physically fit so had to drop down a size to 2.2kW. Modifications still had to be made: the capacitor containing terminal box was removed and a single module pattress box fitted in its place. An aluminium mounting plate was then fabricated and fitted to the bottom of the motor mounting plate and the capacitor box fitted. Flex conduit was then fitted between capacitor and pattress box. Due to the increased current demand of the single phase my next job will be to upgrade the starter(start/stop)
Hope someone finds this useful and please feel free to contact me for more info if required

J.

 

[Farmer Giles]

I bought a 10hp "whole workshop" 240v single phase to 415v 3 phase converter. I run several machines including a 5hp compressor and a 7.5hp metalwork lathe from it and soon some woodworking machinery too.

I bought it from Direct Drives and it includes soft start to minimise inrush current and is wired to a 50 amp C type MCB.

I only use one machine at a time, some have two motors including suds pump etc. but if the compressor started up when I was loading up the metal lathe that would probably be bad. It has fuses so the worst thing that would happen is to change a fuse.

It is all digital , not a noisy rotary converter. it cost about 1200 quid delivered from memory, I've had it 2 years without issue, I thoroughly recommend them. Great for old machines with star wired motors and no easy change to delta for 240v inverter use. It came all pre-wired on a pallet ready to fit to your distribution board and with a 3 phase socket on the side.

Probably too much for just one machine but if you have a shop full of old machinery then definitely worth it.

Cheers
Andy