singal or 3 phase motor question

[chester dylan]

A frind has asked me about being able to slow down his belt grinder. My first thoughts were to put a 3 phase motor and a vfd on it but the motor is flange mounted so it could be fairly pricey to find a motor for it.Been round to have a look at it tonight and opend the motor conection lid and it looks like a 3 phase motor with 2 caps on it 35uf and 300uf. It looks like a crude way of off seting the phases and im wondering if i can just remove these and wire the motor in star configeration a put a vfd on it
Motor in question

wireing is excuse the dots when i post it removes blocks of spaces
N-------u1-----w2

35uf----v1------u2-----L
l
l______w1.........v2
............l............l
............l__300uf_l

 

[Pete.]

From the connection plate it seems to be a single phase motor, but the motor tag clearly says 3 phase.

 

[chester dylan]

To me if you ignor the 2 caps and just look at U V W windings id say its 3 phase and the 2 caps are there to get it to run of singal phase
any singal phase induction motor iv seen has 2 windings and one cap to ofset the frequency for the outher winding and by changing whitch winding the cap is on changes the direction

 

[Seadog]

its a 3 phase 230V motor
seemingly the 2 caps are there as start caps (C st )

Motor is greek made by the looks of the makers name, so might explain the non UK standard wiring...

@fixerupper - any thoughts?

A 3-phase motor does not need start or run capacitors.

 

[chester dylan]

as far as im aware (some one corect me if im wrong) a 3 phase motor windings have a 230v suply when wiered in star and 415 in delta

 

[chester dylan]

i think these caps have been added to of set the phase theres no littel box in there to ingage a start cap
by the way thanks for the replys guys if i can get a vfd running on this grinder i will make a knife smith very happy

 

[chester dylan]

id say it looks like "L Single Phase with High Starting Torque"
im thinking that i might check the caps with my meter see if one has got some sort of cut out to act as a start cap.
Only difrence is V2 has no conection on it where as the motor on this grinder has V2 conected to W1 viar a 300uf cap

 

[rtbcomp]

From the wiring diagram in the lid I would say it's a single phase motor with the plate mis-stamped.

The capacitors will be start & run.

You can get single phase VFDs, changing the frequency will change the speed of the motor regardless of phases

 

[Rudi McAnichal]

I am no linguist, but I think ELLAS ELEKTRIK POWER just translates as Greek Electric Power, and is quite likely to be this company, which does have an English language web page:
http://www.hellaselectric.gr/index.php/en/

"cooperates with selected foreign firms" presumably means importer of Chinese products. Maybe their "qualified stuff" could tell you more

Quote: HELLAS ELECTRIC POWER is being active in the Greek market and in the Balkans in electric motors,Water pumps, generators and Alternators commerce. The company cooperates with selected foreign firms and has extensive experience as also qualified stuff for supporting its product.

 

[WorkshopChris]

I think the only way to be 100% will be to note down all the connections and remove all the wires then test the windings with a multi meter.
If 3 phase 220v you should have 3 windings of equal resistance.
If 1 phase you should a start winding and a run winding with different resistances. you may also have a switch pair that will be closed and change to open once the motor is up to speed.
Chris.

 

[Seadog]

as far as im aware (some one corect me if im wrong) a 3 phase motor windings have a 230v suply when wiered in star and 415 in delta

It's the other way round.

 

[rtbcomp]

It's the other way round.

On a dual voltage motor, yes.

Some single voltage 415v motors are connected in star to start them and then switched to delta to run. This is to reduce the starting current.

 

[Pete.]

Yes we have a couple of small concrete saws that do this. There's a dual -position star-delta switch that you have to operate twice, once to start then again once the motor is up to speed. Some guys don't understand why they have to do anything else once the motor is running and then don't understand why the blade stalls so easily.

 

[AndyStobbs]

Can you not just change some pulleys?