Inverter problems why oh why

[cliffed]

After several asks,been told that an inverter speed controller cannot be used on a 3 phase 2 speed,4 pole motor.
All the tech guys,installers etc,couldn't tell me this at the beginning of job,but when testing the motor,it just didn't sound right,2 motors later one call I've made as finally gotten to the cause.
All the specification,was adhered to,so frustrating,what's happening out there.

 

[cliffed]

Yes connection on high speed,links in star formation

 

[westward10]

Does the rating plate clearly show the different speeds and the same or different horse powers.

 

[cliffed]

Yea different rpms,amperage ,min 1.14,max 2.41 amps

 

[cliffed]

All this came to light a couple of days ago,it's just been a lack of information & communication between parties.
The guy I phoned,summed it up really,why would you put a Vsd inverter on that kind of motor,when it already is a 2 speed motor.

 

[westward10]

Stab in the dark, I suspect you have a Dahlander wound motor which is two speed and as it is connected with the link across three terminals it for high speed, this is actually star/star connected. I haven't dabbled with this for years and Darkwood can probably say whether this is correct and whether it will run from an inverter speed controller.

 

[cliffed]

Yea sounds right,I've been told it won't work with inverter,& it certainly don't sound right when controlled by inverter.

 

[westward10]

Have you tried running it DOL without the inverter because theoretically it should run like any other induction motor.

 

[cliffed]

Thought about doing that,but bit worried,just can't connect cables without some protection on motor,not got another starter to try that yet,but an option

 

[westward10]

Yes you need to control it through a starter or a switch fuse. I think you need to do this to confirm the motor is okay. Maybe when Darkwood comes back on he can throw some light.

 

[cliffed]

Thanks will do that when I'm back on job,it definetly wants sorting ,there's been so many involved,& nothing seems to happen.

 

[westward10]

Who put the link across the three terminals.

 

[cliffed]

I did,being either star or delta connection

 

[westward10]

Ah I have been thinking about this and assumed the link was already there so my Dahlander theory could be incorrect. What you "could" have is a double wound motor which is essentially two motors in one, a high speed and a low speed. One set of terminals for high speed the other for low. Ditch the link and just connect to one set of terminals, if it is definitely a two speed motor it may function now high speed on one set of terminals reconnect to the others for low.

 

[cliffed]

Yea,not tried that yet,will see thanks.

 

[sunray]

Is there any drawing or other info about links on the motor?
There are too many ways of making a motor run and different speeds to guess.