Electrical Question - 3 Phase Motor starter

[munkypuzel]

Hi All,

I am looking for some electrical advice. I have a Planer thicknesser with the 'guts' of the starter missing. It has been wired 'straight through' as was being used on a phase converter and was switched from else where (sounds dangerous!)

I would like to fit a new DOL but am struggling to work out which rating to buy. The Planer has two motors, a 3kw main motor, that is wired in parallel with a 0.375kw motor for the drive.

Does anybody know how to specify the correct starter?

Many thanks
Mark

 

[NetBlindPaul]

Yes I do know how to spec up the correct starter!
Fiorst though please give us some more info on the machine, make/model?
I have seen this before it is common on the Wadkin BT series, & I don't like it, and, it does not comply with current legislation for machinery used in business undertakings.
I can sort you out with this either way, DIY or for business use.

 

[munkypuzel]

Hi and thanks,

The machine is a Sedgwick MB Planer Thicknesser, it looks identical to the current model apart from the controls!

Thanks
Mark

 

[munkypuzel]

Hi, Does anybody have a Sedgwick MB and if so could you tell me the rating of the starter? I cannot seem to find out what the overload current rating should be..

Thanks

 

[NetBlindPaul]

Hi Mark,
Sorry for the delay, I have been working a few long hours 48" band resaw Tuesday in North Wales, I live in South Wales, local prison all day yesterday to do their machines then back to the workshop to get the parts modified for today, Gloucester on a Wadking BEL spindle moulder this am, then local school on a startrite table saw, bandsaw, and a lathe this eve, I do them after the kids go home!

Right, is the machine for business use or for home/hobby use outside a business please.

 

[munkypuzel]

Hi Paul,

This is not for business use, It is a restoration project. I have the baby version of this planer for my own hobby use. I really dont want to convert this machine to 240v as it is has two great motors on it already, I just want to put it back how it should have been. I cannot vouch for where it will end up one day though, I just really enjoy taking them to bits cleaning them up and puting back in to use.

I understand if you feel that you cannot give advice on this though,

Thanks
MP

 

[NetBlindPaul]

MP,
Not a problem giving you advice.
You can't worry about where it may end up Caveat Emptor and all that.
As you are not a dealer, you would not have the responsibility of ensuring it meets legislation if you were to sell it into a business, it would be the buyers responsibility to ensure it complies bfore use.

So, to the details, you can't protect both motors from one starter overload.
You would need 2 overloads with 2 contactors.
These can be bought, or built.
Do you have a 3 phase supply available for testing?
If you size the o/l for the big motor the small one will have little or no protection, if you size for the little motor it is doubtful the large will run., sizing for both will reduce the possibility of proteciton on the large motor and almost certainly eliminate it on the small.

The next bit depends on whether you want a single button or 2 for the start.
This has more to consider than may first be obvious, even for a DIY user.
If you have a planer / thicknesser and you do a lot of sufacing then you generate a lot of shavings & dust. Unless you can stop your feed system on the big machiines you can't put an undertable extraction hood in place.
So if you went for 2 start buttons then you could run the cutter block alone and thus use an under table extraction hood.

Are you looking to buy or make a starter, if you are looking to make how are your wiring skills?
Would you be looking to make one to meet the required standards or just to work?

Let me know on these points and I'll get back to you later.

 

[munkypuzel]

Hi Paul,

Thanks, yes, the two contactor and overload protection makes complete sense, I will have a seperate starter for both now. What I find strange is that it appears that originally it only had one of each which as you say would have left the smaller feed motor without protection..

My wiring skills I would say are above average (HNC electronic engineering, 20 years ago though!), although I will probably buy a couple of starters for this, I will take a look at the price.. I could comfortably wire these sytems from scratch but guess that by the time I have purchased the enclosure, switches, contactors etc it would prob work out more expensive?

Thanks Mark

PS. I can get access to 3 phase for testing, my neighbour has it in his workshop.

 

[NetBlindPaul]

Don't use 2 separate starters as they must be interlocked, this is not my suggestion, you need one starter with the two contactors & overloads in as you will need 2 start buttons and 1 emergency stop button at least, preferably one emergency stop button each end of the machine.
2 e-stops should be fitted to comply with legislation if you have an eye on selling this into a business undertaking.
The feed motor must not run unless the cutters are running.
Please also remember NOT to use wiring materials that would normally be used to wire buildings, such as twin & earth, or the singles known as 6491x as they are unsuitable for machinery, you should use what we call tri-rated for singles, sy or yy for cable really with suitable glands, remembering that the electrical system on the machine needs to be dust tight to IP65 at least.
Also in this case you cannot use 400V control if you wish to comply with legislation.
Come back to me for some more info if you wish.

Paul

 

[munkypuzel]

Thanks Paul,

Lets see if I have this right:
One unit, two contactors and overloads, with a mechanical interlock, that only allows the second motor to be started (feed) once the Main (cutter) motor is running. - (I hadnt thought of this, but i guess feeding into a stationary cutter block would be a very bad idea!)

Ok, if I had one starter for Main cutter motor, with a second smaller starter for the feed that was wired from the 'output' of the first starter so it only operated when the first contactor was closed, would this be a valid solution also?

I understand the emergency stop requirements as I do cable/IP requirements, ive got plenty of SY knocking about..

Thanks
Mark

 

[NetBlindPaul]

Mark,
Electrical interlock is fine, just use an NO Aux on the main motor contactor.

Just remember to wire the O/L Aux contacts in series with the E-Stop and BOTH contactor coils.

Thing is with 2 seperate starters the e-stop chain would be more difficult to implement, and also you would have a stop button on the cutter and on the feed, so you could stop the feed independently of the cutter, OK, and when you stop the cutter the feed would stop due to the electrical interlock, so you could achieve the required function, it just does not meet "requirements" when I do such machines I always do 2 starts & one single e-stop at each operator location, i.e. infeed & outfeed. That is one stop "chain".

HTH,
Paul