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By kinsella
#986232
3 Phase to Single Phase : Startrite 275 conversion from 3 phase using Single phase input.

Colleagues
The following is my take on how I converted a 3 phase machine and it is meant to help others on the forum as I note it’s a common question on here for all sorts of 3 phase motors. (The assumption is you are either competent to undertake the work or you will seek professional advice, I take no responsibility, as it is your responsibility to follow proper procedures for your equipment or wellbeing, so if in doubt seek professional advice) Luckily there are loads of very experienced colleagues on here who will probably highlight were I could have taken alternative route or also to correct me if I actually get my facts wrong . But in my defence the following solution is either because of time, cost or ability. I used this forum and professional colleagues in my day to day job in construction management and colleagues in maintenance and electrical design engineers to bounce my assertions passed. Which helped me understand where I was wrong? Also, to be fair I think the general domestic DIY’er situations will be very similar to mine and this may give some pointers. I will add links where appropriate for further references.

Image 1.JPG

I’ve recently received a Startrite 275 that was going to go in a skip. So as someone who has been on the lookout for a salvaged machine for a while. The timing was brilliant and the value was also good £0. The machine is 3 phase. As a weekend DIY’er, using direct 3 phases was not an option. So began the investigations on how to get the machine working. I found several treads on the forum which helped considerably.

These are linked below.
topic90119.html
topic20930.html
topic66355.html
topic77410.html

My options were as follows:
1. Sell the salvaged saw (I was not going to let a machine of this calibre go, as it was too good to even consider letting it go and the womble in me wanted to get it working

2. Buy a new single phase motor. This proved to be quite expensive as it meant replacing the motor, switching, pulley etc. So if it was just a motor replacement, it might have been cheap.

(Aug 2015 prices, quote extracts)
http://www.altsawsandspares.co.uk/spares.html
Part number Starcro 043 is the new replacement 240 volt 2HP foot mounted motor to suit, this has a 24mm diameter shaft, these are £236.00+vat.
If you need a 24mm bore pulley these are £61.20+vat
Part number KS0011 is the new 240 volt start/stop unit to suit the new motor, these are £85.00+vat
Carriage would be £15.00+vat, delivery 3-4 days from payment.

To be honest if money is not a problem, this is probably the easiest option. The company ALT Spares are excellent and this was where I was going to go until I realised I needed to buy a holiday for the family. So it was NO-Machine and a holiday. Or a slightly shorter holiday and a cheaper fix.

3. I also looked at using my existing Scheppach TKU table saw to see if I could salvage all the parts, i.e. the motor and switching. Unfortunately without doing a Heath Robinson this was a very awkward route as the motor mounting fixings were nowhere near the existing mounting points (didn’t match the Startrite), the arbour also looked like it wouldn't line up correctly. I gave up on this option very quickly as I figure I would butcher a perfectly working existing saw and a working solution wasn't guaranteed.

4. The next options are to keep the 3 Phase motor and use a converter or an inverter to run it.
A handy document on workshop motors can be found here, which explains the various motors in use. "Use of Induction Motors In The Home Workshop" by R C Minchin
http://homepage.ntlworld.com/bob.minchi ... Issue3.pdf

Having decided on keeping the 3 Phase Motor. The next options were as follows:
5. I got check prices for an inverter and a converter. A handy explanation is above in item 4 on the difference as I think these are commonly confused and intermixed assuming they are the same.

6. The first thing I had to do was take the cast iron top off the saw. I don’t have side access through the house, the workshop is at the back of the garden and the only option was to dismantle. Taking the top off is easy as it is held on with 8 bolts. The top is located onto the saw base with two locating pins. Once undone the top just lifts off. The top and bottom are both extremely heavy. But my wife (skivvy labourer) and I used moving skates and moved it through the house to the shed at the rear of the garden.
Image 2.JPG
Image 3.JPG


7. Once in the shed, I took the motor off to get easier access to it, to read the motor plate details. I opened up the wiring plate to see what alterations would be needed to the Delta/Star wirings. (it’s assumed by now you understand the difference between high/ low voltage ie Delta and Star, if not go back to item 4 and read the referenced document) Also when the inverter arrived it would be easier to test with it on a bench rather than in the body of the saw. See an example in the image below in a test state.
Image 4.JPG

A YouTube video of the motor wiring etc can be viewed here:
https://youtu.be/SVq6MGBIltw

8. The motor on my saw was dual voltage, ie Delta and Star. See image. So my options were to either use a converter but I could also use an inverter. The option of using an inverter was to wire the motor to low voltage (Delta) and use an inverter to maintain the 3 phase low voltage supply. Ie you cannot convert 240v domestic supply to 415v without others boxes of tricks (not part of my research). So the only option for me was to use three phase on low voltage (ie domestic 240v supply size). You will need to check your motor. If you read the document link above in item 4 it will help you decipher if your motor is high voltage or dual voltage. If high, it just means your route to get your existing motor working is slightly different. Ie you’re back to items 2 or 3 using a converter.
Image 5.JPG


9. Having watched a few videos on YouTube. Changing a motor from Star to Delta seemed to be quite easy, as all you have to do normally is move a few metal tabs and it normally tells you on the back of the wiring plate. Well, that was until I opened my motor wiring box. There were no connecting wiring links and it didn't look like any of the Star wirings on YouTube. But after a few internet searches I realised that it was OK, basically, the modern UVW outputs are also knows as ABC, XYZ and so on. Luckily I could see where ABC were on the high voltage wiring, the wiring details were clear on how to rewire the motor to low voltage.
Image 7.JPG
Image 8.JPG


10. I then focused on the inverter and I looked as several suppliers of inverters. The key item to note is that you will need a single phase input to a 3 phase output inverter. This is extremely important. If you salvage an inverter from somewhere you will need to check the input and outputs, otherwise you may need other bits of kit to get the inverter working. It should say on the unit detail plate.

11. My solutions were cost driven and were mainly to keep the pricing down to a minimum. Due to costs I opted for an inverter after having researched inverter manufactures and converters. The best pricing was an Invertek inverter. The ode 2 12150 1kb1x was the best option as it had an IP wall mount enclosure, it also had a dust proof and water proof rating. It’s a single to 3 phase unit. See link below. As of Aug 2015 it was circa £250 all in cost inc VAT and delivery. Some of the other costs for converters were in excess of this up to £600.
https://www.motorcontrolwarehouse.co.uk ... 1kb1x.html
Image 8a.JPG

A video of my investigations and connections can be viewed here: https://youtu.be/SVq6MGBIltw

12. A point to note is most of the existing switching on my Startrite was incompatible with the inverter. More importantly, the wiring of the inverter needs to go directly to the motor with no switching etc. between the inverter and the motor. i.e. no NVR switch, on/off or emergency off switches. These need to be done separately into the Control Terminal Panel (CTP) on the inverter. The manual explains this. You cannot just wire the old 3 phase wires into an inverter and all the old switching will work. If in doubt contact the inverter company and they tend to be very helpful. (Invertek were!!)

13. I managed to save the old emergency stop switch off the old saw and wire that into the CTP so I still kept the kick stop emergency brake on the existing saw configuration.

14. I bought 5m of 4-core cable from Screwfix. I also have a Startrite Mercury II drill press to tweak also, so I need more 4 core cable.

15. I then connected everything up roughly and tested the whole configuration before mounting it permanently into the saw, this was for ease as it was easier to do this at a bench and fine tune everything. A video of my investigations and connections can be viewed here: https://youtu.be/SVq6MGBIltw
Image 4.JPG


16. I found a few YouTube videos on my Inverteck inverter as follows. These were extremely helpful in terms of wiring them up and adjusting the settings.
https://youtu.be/ROu2kd_Z-bk
https://youtu.be/HAL97NTx2v0

17. I connected all the incoming supplies as per manufacturer’s instructions. See video.
https://youtu.be/STta919XOWk

My investigations can be viewed here: https://youtu.be/SVq6MGBIltw

18. What did catch me out was, after adjusting the settings to make the motor run from the main panel and not a separate control switch; I also adjusted the volt rating of the inverter to match the 3 phase motor to protect the motor, mine states 5.2 Volts. After setting all the settings. I then pressed the green start button to start the motor and…… #-o #-o ……nothing happened. I turned it off and rechecked all the wiring connections…………… restarted again and……… #-o #-o ………. nothing…………….. I did it a few time as we all know when it doesn't work first time, do it again and again until caveman brain works out it’s not working……………………….. I scratched my head, I scratched my bal………… nothing. I then checked the error log on the inverter and nothing………… :? :? ………… At this point I stood there thinking I've done everything right and it isn't working and was wondering if the motor had had it as I had not witnessed that it had ever worked. I was contemplating following a process of elimination to test circuits of the motor which was easily hours and hours of work that I'm not even competent to do. I thought no way, I then relooked at the settings and suddenly it dawned on me. The motor speed is set from the panel and the default is zero and I thought that doesn't look right. I think the default in the setting assumes a rotary connector to adjust the speed of the motor and thus its default out of the box is zero. I pressed the up arrow and nothing happened, or should I say nothing perceivable happened. As the speed ramps up in 0.0 increments. i.e. by 0.9% the motor is probably moving but you’d never pick it up visually. I ramped it up and by 10% I noticed it was moving. Then at 50% if was giving it welly!. I realised it was just a setting and everything was ok with the world. And saved me a tonne of abortive work. The great thing with this inverter is it remembers the last setting. So when I stopped and restarted it, it immediately went back to the 50% that I previously set. i.e. when I'm up and running and I set it to 100%, it will always be 100% when I restart unless I adjust it manually. As it’s a table saw and not a drill or lathe. I will never alter the variable speed that I can see at present. Mind you I have two sizes of blades to put in the machine and so it may need adjusting.

19. Having proved everything works, I moved to final install and permanent mounting.

20. I then mounted the inverter onto the table saw. The inverter is quite bulky but the overhand on the Startrite is considerable so I opted to mount directly to the base unit and use a single phase cable with a standard plug. I also connected the old emergency stop switch to ports 1 and 2 on the CTP. I wired the incoming single phase supply as per manufacturer’s instructions and then the 3 phase outputs. Connecting all earth cables as appropriate, used rubber grommets so there is no metal to cabling scenarios without rubber seals or grommets. Hey presto. I'm now operational.

21. Cost of Startrite £0 as its salvaged. Cost of inverter £250, plus 4 core cable £10 another few £’s for grommets. Due to its size and my limited space, i welded up a wheel base and bought some heavy duty castors from Screwfix for another £10. So from non-usable 3 phase saw to usable 3 phase saw equated to £280.
Image 11.JPG


Summary:
A point to note, while I don't mention the earthing of cables, the Inverter is earthed and the 4 core cable is earthed to the motor housing (you can see the green/yellow cable under the UVW wiring in the video) so the whole set up if fully earthed and tested before I moved from any of the wiring stages to ensure that there wasn't an existing fault with the motor.

Hopefully those of you who find yourself in a similar position may find this post useful. I am no electrician and only know basic knowledge but from research on this forum and the PDF guide on motors I managed to go from zero knowledge on motors to turning a 3 phase saw that was unusable to me to a working 3 phase saw. Feel free to post questions, i may not be able to answer them but the colleagues on here have been extremely good in jumping in and posting clarifications.
Image 11.JPG
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Last edited by kinsella on 15 Aug 2015, 13:14, edited 2 times in total.
User avatar
By kinsella
#986277
Myfordman
If you are R C Minchin, that was a very informative document and i personally wouldn't have moved from zero knowledge without it, so if it is you. I thank you on behalf of this forum for taking the time to write it.
By Myfordman
#986364
It was written as a distillation of the responses I'd made here to specific questions on induction motors and in a style that I hoped would enable people to have done exactly as you have, read, learn and put into practise. I was here as 9fingers for many years but then made unwelcome for a while before reappearing in my current guise where I seem to be tolerated once more.

I revise the paper from time to time so if you or other readers have suggestions for any expansion/clarification then feel free to PM me and I will look at the suggestions.
User avatar
By kinsella
#986392
=D> Yes, I remember you. You've replied on treads that i have done before. Yes, as a electrical moron I will take another look and offer some suggestions. I note i had one of your earlier versions and then came across the revised version which is even better. I'll get around to it soon and PM some suggestions.

Put it this way, i have a working Startrite because of your motor document and I'm extremely grateful if you haven't noticed. =D>
By dickm
#986455
...and the cheapskate solution, as used on my 352 bandsaw? Keep an eye on Gumtree, ScotAds or similsr for a suitable single phase motor - foot mounting ones are relatively common and mine was about £50 from memory. (There's a 2hp motor in ScotAds this week.....hmmm....should I upgrade??....)
Swap motor for the original, strip out redundant wires and parallel the overload trips in the existing switchgear. Switch on and use!
Did subsequently put in a proper NVR switch, but the bodge worked for some time. Total cost still under £100

(sorry about typos - only got one useable hand at the moment. NOT because of a saw incibent!)
User avatar
By kinsella
#986520
dickm wrote:...and the cheapskate solution, as used on my 352 bandsaw? Keep an eye on Gumtree, ScotAds or similsr for a suitable single phase motor - foot mounting ones are relatively common and mine was about £50 from memory. (There's a 2hp motor in ScotAds this week.....hmmm....should I upgrade??....)
Swap motor for the original, strip out redundant wires and parallel the overload trips in the existing switchgear. Switch on and use!
Did subsequently put in a proper NVR switch, but the bodge worked for some time. Total cost still under £100

(sorry about typos - only got one useable hand at the moment. NOT because of a saw incibent!)


Yes, a good solution. The point of my tread was its about capability (ie limited). Over the years I've had opportunity for loads of 3 Phase kit, i block it out now as its too painful to recall the stuff that I've turned down over the years (ALL FREE!!!!, a medical bandsaw - think about it..... not nice..... closures of University workshops and the kit in them is top notch and old. Wadkin, Startrite, and loads of other old brands) and i immediately turned down as its 3 phase. I finally decided to work out how to use them. I've now started collecting motors for exactly your solution. But as its a table saw i thought I'd go the extra mile and get it working properly and keep the original motor. The saw will still be running when i'm not!!!

But to take your point, my next project is a 3 phase Startrite drill press and there is no way i'm paying £250 to get it working. I'll either find a cheap single phase motor like you point out or use capacitors to get it running.
User avatar
By Andy RV
#986584
Good job, I've changed motors in the past however i'd prefer to go 3 phase through an inverter these days, much more controllable!

It's worth looking at ebay for inverters, I've just done a quick search and found a number for around £150 which would of worked for your saw.

For pulleys look at the taperlock type, they're fantastic and cheap if you shop around.
By Myfordman
#986668
kinsella wrote:
But to take your point, my next project is a 3 phase Startrite drill press and there is no way i'm paying £250 to get it working. I'll either find a cheap single phase motor like you point out or use capacitors to get it running.



A pillar drill will possibly be only 1/2hp and so a used inverter off the bay should be quite cheap. A variable speed pillar drill is a joy to use and no more drilling at the wrong speed because you can't be bothered to change a belt. Programme the inverter to give 10Hz to 100Hz and fit the belt in the middle pulley in the range and you will hardly ever have to move it.

If your motor is 415v only, then there are solutions for that too without paying silly money.
User avatar
By kinsella
#1028945
Myfordman wrote:
kinsella wrote:
But to take your point, my next project is a 3 phase Startrite drill press and there is no way i'm paying £250 to get it working. I'll either find a cheap single phase motor like you point out or use capacitors to get it running.



A pillar drill will possibly be only 1/2hp and so a used inverter off the bay should be quite cheap. A variable speed pillar drill is a joy to use and no more drilling at the wrong speed because you can't be bothered to change a belt. Programme the inverter to give 10Hz to 100Hz and fit the belt in the middle pulley in the range and you will hardly ever have to move it.

If your motor is 415v only, then there are solutions for that too without paying silly money.



Myford
I did exactly what this thread suggested and picked up a small 1/2ph inverter for £20 (inc delivery) off ebay and now have the drill press working as you all suggested.

Myfordman. As a man of mystery are you also myfordboy on youtube????
By Myfordman
#1028953
kinsella wrote:
Myford
I did exactly what this thread suggested and picked up a small 1/2ph inverter for £20 (inc delivery) off ebay and now have the drill press working as you all suggested.

Myfordman. As a man of mystery are you also myfordboy on youtube????



Glad to hear you got sorted ok.

No connection with myfordboy at all.
By tomasg
#1028970
Hey Kinsella
Have you made a zero clearance insert for your saw since making the video?
Im wondering if you noticed any blade deflection upon startup
Looks like your making use of the soft start already.......
Have you adjusted it more to accommodate for this or for your 13a plug ?

Since you are posting about your experiences after reading Bobs fantastic motor/VFD write up,
Ive got a question or two for yourself or anyone else in the same situation (hammer)
For those who have say a......... 3hp motor running from a 13a plug.
Trying to get more of a sense of the performance from a weak supply ,It can be difficult to get even a ball park figure
because some things can be so variable ....
But ..On the assumption that some folks have a weak supply and/or living out in the sthicks ie...

"For instance my lights dim when my kettle boils ,I must bring the kettle out to the shed to try and see if it dims the lights in the house ,the shed has its own 32a MCB
Although the washing machine and the cooker will work full blast with only very occasionally a slight dim of the lights

"Provided you or your sparkey friend checks that the CABLE running from that 13a socket to your Consumer Unit MCB is properly rated so it wont go on fire"
Now for another assumption ..All of us using 13amps are patient fellows and gals ....
How much do you blow that fuse ??? for example
could you crosscut the ends off reclaimed iroko or teak door stiles and strechers say 30 cuts worth without the fuse blowing or the cable /plug heating up too much ?
aaaahhhuglaugh,,,,,didanyonewirea15ampplug sorry I think i might have a wilex bad cold coming on that affects proper use of the keyboard
There was a post a while ago on this type a thing regarding 15a bodged plugs It would be a good read for entertainment purposes ...anyone have a link ?
Love to hear some folks opinions
Thanks for reading

Might look into that invertec drive as the huanyang hy02d223b i had worked up until i got around to actually using it
Does it have the hardware/software for a braking resistor or for a potentiometer ?






Can you run a 12" blade with that supply ,
Provided someone with a 13a supply is patient
User avatar
By kinsella
#1029051
Tomasg
Loads of questions there. I'll see if i can go through them.

i haven't made a zero clearance yet as oddly i haven't needed to. I had two or three for my old Scheppach saw. I eventually will but it hasn't been a need yet. The factory metal one is pretty good for most jobs.
Re domestic 13A supply. The only thing i've noticed is that the saw pulls more amps on say Oak and the Invertec then tripped as i have it set to match the max Amp on the motor plate, but when i resharpened my blades i haven't noticed the problem again. Its obvious that if you go from 3Phase to Single you get something less. But generally this saw is robust and reliable even working off an invertor.

Regarding wobble or anything. No i haven't noticed anything that causes me concern. Its an imperial bore, i think its 5/8 from memory so i have the inserts in the blades to get from 30mm bore to 5/8. I was thinking if they didn't go in straight that might induce wobble, but as i say. The saw is performing perfectly. Actually its a joy to use.

The only machines i have that make the lights dim or flicker are my Axminster compressor, for some stupid reason i worked out, it has a 13amp plus but pulls 20amp to start on a cold day and regularly blows a fuse, such that i have a full packet on hand just for this machine. Also when i press the stop button on my Perform P/T, this makes the lights flicker.

i have a armour cable from the main dis board 4mm cable. Probably should be bigger but i only use one machine at a time (dust extraction exception) and never for long periods that would actually warm up the cabling. I've checked it a few times over the years by just holding the cables to see if its warm and its never got hot. The MCB has never tripped, other than me testing it.

Answering you last question, i use 12" blades, Dado's etc on the Startrite and my Wadkin Radial arm. Never had any electrical issues.

The Invertec is a fantastic bit of kit, "Does it have the hardware/software for a braking resistor or for a potentiometer ?" the simple answer if probably yes, definitely for the Potentionmeter as you can see that working on the Youtube videos they post, if you email them, they will answer your questions, i found them exceptional in the customer service and as complete home DIY'er i had assumed they wouldn't answer my question as I'm not trade or industry but was very pleasantly surprised with the extend they went to help me.

Hope that helps.
By tomasg
#1029125
Thanks Kinsella
That gives me a better impression on how much juice a 12" tablesaw needs .
My blade wobble question was mainly to do with shop-made zero clearance table inserts
and the starting forces from the belts being on one side of the blade might nip the insert every
time you turn the saw on .
Obviously the soft start will counter this ,but I wasn't sure if you needed to further do some slight adjustment .
Having never started the/a tablesaw just trying to clear things up a bit ..

My 275 got a hefty knock on one of the levers that broke the handles off ,
just have to weld new handles back on the main part again
but since the base made out of flimsy sheet it might have deformed and prove to be problematic.
Wont know till its up and running though
So Its really good to know you dont notice any considerable starting kick of the blade
or other blade wobble scenarios with the 275
Thanks again
Tomas