Thread: Another VSD Question !

Is that a two speed motor? (The data has two rpm ranges)
If so, no. Even if not, it's unlikely that a 5 hp motor can be run on 240v three phase, it's probably wired 440v delta already.

How many terminals are there in the peckerhead?

(sorry, I don't know the local name for the box that contains the terminals on a motor)

Greg

Hi Greg ,
thanks for the reply the motor has six wires going into the top of the motor but i cant get in there to get a photo of how they are wired . I will take a photo of the main switch box of the lathe so you can see the wiring there if it helps .

cheers Plushy

p.s are you still interested in that transformer that i posted about in the Herbert lathe thread ?

here`s the wiring photos . sorry about the phone camera quality .





The six black wires that are in the middle in the last photo are the ones that connect too the motor . There is only a on/off swith at the front of the lathe as far as i can tell there is no speed switch for the motor .

Thanks for any help .

Hi Plushy. I can't recall the transformer right now, I'll have to search the topic to jog my memory. Was it a 415/240v by chance?

Your lathe's contactors and the six black wires kind of confirm to me that it's a two speed motor alright. Is there no "star" or "wye" symbol anywhere on the data plate for the motor?

I'm guessing that it is connected in delta already, and therefore cannot be run from a 240v VFD. Two speed motors pose another problem also in that usually only one winding can be run from the vfd.

Is your problem that you don't have three phase, or did you just want an easier speed control scheme?

Greg

Hello again. Yes I am interested in the transformer. I'm also curious if this was used with this motor?

Greg

Originally Posted by gregoryq

Is your problem that you don't have three phase, or did you just want an easier speed control scheme?

I Dont have three phase is the problem and cant really justify the big cost of a phase convertor to power the 5 hp motor and i am not comfortable enough with electrickery to build my own . I suppose i could buy a 5 hp single speed 240/480 3 phase motor and put that in if i wanted to run a VSD ? I will have another look to see if the motor has a delta or wye marking anywhere .

heres a photo of the motors data plate



The transformer was offered to me in the deal with the herbert lathe apparently the transformer was to power a magnet in a scrap yard but they scrapped the idea pardon the pun

I am also reluctant to fork out for aphase converter as i might be moving in the next year to a place that has three phase available .

Originally Posted by gregoryq

How many terminals are there in the peckerhead?

(sorry, I don't know the local name for the box that contains the terminals on a motor)

Greg

Terminal Box will do Greg.

The starter is a Star/Delta starter it is not a two speed machine. The two speeds and currents on the name plate coincide with the different voltages that the motor will happily accept.

The motor has six wires (two per winding) directly connected to the starter. The starter then takes care of the star or delta configuration.
The star/delta starter is a reduced current starter (so you don't blow the fuses every time you start) that initially starts in star and then switches to delta once the motor is up to speed.
I think the 380/440V 3 phase are different standards from Europe. The motors were manufactured to be suitable for a number of countries. Our 415V 3 phase slots into that range very nicely.

I wouldn't think that motor was suitable for the single to three phase VSD treatment.
I'd keep an eye out for a big 1 phase motor. You may get away with less than 5 HP if the lathe is heavily geared. Hang on to the 3 phase set up in case you make the move.

I was wondering why I missed the star/delta aspect of the motor...I guess that I was expecting that to be noted on the data plate.

The advice to look for a suitable single phase motor seems like the best given the possibility of a move to three phase soon. Ebay seems to be a good source for motors.

On 5 hp vfd pricing...I expect that you'd be paying over $1000 shipped for a vfd in that power range these days given the exchange rate. The last time I was considering a 5hp VFD the only single phase input model available was from Polyspede at $600 ish U.S. That was a few months back, I think that there are other brands now available in the 5 hp size. Motors that size are not commonly found here with a star winding however, but there are some around.

If you aren't going to be using the lathe for a production load, perhaps you could get by with a 3 hp motor in the interim, keeping your 5 hp motor nice for when you shift houses.

Greg

I'll send you a pm about the transformer...

The VSD i was looking at is this one from evil bay
http://cgi.ebay.com.au/3-7KW-5HP-Bra...1%7C240%3A1318

The other thing i noticed is there is a built in cutting fluid pump that is powered by the 3 phase if i swap to single phase motor i will have to disconnect this and rewire it in later ?

So what is the difference between star , delta and wye ?

If the starter has delta and star cant i disconnect the star part and use the VSD direct too the Delta wiring on the starter ?

Thanks for all your help guys i am slowly getting a understanding of this electrickery

Originally Posted by NCArcher

The starter is a Star/Delta starter it is not a two speed machine. The two speeds and currents on the name plate coincide with the different voltages that the motor will happily accept.

The starting arrangement may well be a star-delta starter, but the two speeds quoted on the name plate are nothing to do with the voltage. The speed of an induction motor is primarily controlled by the frequency of the supply and the poles in the motor (with some ~4% "slip" as well). The motor appears to be a 4/6 pole motor - i.e. it appears to be a two speed motor.

Originally Posted by Plushy

So what is the difference between star , delta and wye ?

If the starter has delta and star cant i disconnect the star part and use the VSD direct too the Delta wiring on the starter ?

Plushy,

"star" and "wye" are the same. The three-phase winding and be connected to form a triangle (delta) or a star/wye.

If the switch gear is indeed a star-delta starter, (initially starts in "star" with 240V across a 415 winding, and then switches to run in delta with 415V across each 415V winding), the winding in the motor will be 415V windings - no good for the VFD in your link. What you really want is a 415V motor that runs in star (240V windings) and has the ends of the windings brought out so that they can be changed. Have a look at this thread for an example https://www.woodworkforums.com.au/showthread.php?t=78070

Since the motor appears to be a 4/6 pole arrangement, it may have some very interesting winding arrangements inside, so all may not be lost. If the switch gear is actually speed changing gear (rather than a starter), the motor might be a star 415V.

I remember seeing that VFD recently and was wondering about it. Is the manual for it available online somewhere? It may be an OK unit, but I am unfamiliar with the term "IGBT Space Vector". As I understand it the better drives are described as "vectorless" constant torque, and they do not require any encoder (speed sensing) feedback from the motor to provide stable speed under load.

The drive in the link is obviously Chinese made (judging by the price and the choice of fonts for the labelling). That prompts the obvious questions about documentation, reliability, accessories like remote input pads, terminals for remote potentiometers, etc.. On the other hand, the seller has good feedback and offers help, so maybe its OK.

Originally Posted by chrisp

The starting arrangement may well be a star-delta starter, but the two speeds quoted on the name plate are nothing to do with the voltage. The speed of an induction motor is primarily controlled by the frequency of the supply and the poles in the motor (with some ~4% "slip" as well). The motor appears to be a 4/6 pole motor - i.e. it appears to be a two speed motor.

I appologise Plushy, ChrisP is spot on.
It does appear to be a two speed motor. 4/6 pole. With only 6 leads coming from the motor the control gear may be a speed changer but there would need to be a switch somewhere to change between the two speeds.
On closer inspection of the photos, the bottom contactor looks like it might control the lube pump and the top two are to select the speed.
It's not a star/delta starter at all. Sorry to lead you down the wrong path.