Motor connected in star not delta

[chid22]

Hi all just looking for a little advise was recently working on a ventilation control and during the works noticed that the 4kw 400v motor was connected in star when clearly the manufacturers instructions stated the motor should be in delta. After sorting the control I changed the motor connection to delta and it run with no problems.

However after a few weeks I have now been told by some one based on site that the motor will not run under load and the inverter is tripping out on over temperature.

My question Is would running a motor in star when under load damage the motor in any way? It was always my understanding when in a star configuration in a star/delta start up you generally get a lower current when in star. Wish I tested the motor now but never did.

As you can probably tell motors are not my strong point so any help much appreciated

 

[telectrix]

over to you, tony.

 

[snowhead]

My question Is would running a motor in star when under load damage the motor in any way? It was always my understanding when in a star configuration in a star/delta start up you generally get a lower current when in star. Wish I tested the motor now but never did.

As you can probably tell motors are not my strong point so any help much appreciated

Not where an Inverter (VSD) is involved.

 

[i=p/u]

start in delta and switch to star .. oj i know nothing

 

[chid22]

Not where an Inverter (VSD) is involved.

This was my thinking. Am I right in saying in star the motor would have less torque? If so it makes no sense as previously in star the motor ran but now im told it's as if the motor has not got enough torque to start the load and then goes out on overtemp via the vsd

Wondering if one of the windings may have failed
Any other ideas?

 

[silva.foxx]

... noticed that the 4kw 400v motor was connected in star when clearly the manufacturers instructions stated the motor should be in delta. After sorting the control I changed the motor connection to delta and it run with no problems...

First and foremost:

If it aint broke don't try and fix it else you'll bugger it up!
​

Secondly:

What exactly were the details on the rating plate?

 

[chid22]

First and foremost:

If it aint broke don't try and fix it else you'll bugger it up!
​

Secondly:

What exactly were the details on the rating plate?

Not got the exact motor plate details at the moment unfortunately but like I said only changed it because it clearly stated in the manual left on site the motor should be connected in delta.

 

[silva.foxx]

Not got the exact motor plate details... only changed it because it clearly stated in the manual left on site the motor should be connected in delta.

Always go by the rating plate fitted to the motor. Manuals are subject to typo errors or equipment is superseeded after writing. The plates are straight from the manufacturers.

By applying upto 400v across the windings in delta, as opposed to 400v across two windings in series in star, overheating is very likely...prior to inevitable burn-out.

 

[chid22]

Always go by the rating plate fitted to the motor. Manuals are subject to typo errors or equipment is superseeded after writing. The plates are straight from the manufacturers.

By applying upto 400v across the windings in delta, as opposed to 400v across two windings in series in star, overheating is very likely...prior to inevitable burn-out.

I understand that as current would increase.

How about for the opposite way around. What if the motor should be in delta but has originally been connected in star?

Thanks for your help

 

[silva.foxx]

What if the motor should be in delta but has originally been connected in star?

Then you'd expect the motor to have struggled in star.

 

[Swicade]

Been along time since i played with inverters but from what i remember (back in the day) an inverter throws out 3phase 240v and not 3phase 415v.....so if you've connected the motor to Delta as the plate stated 400v was Delta, 240v (the right connections for inverter control) would be shown as Star connection.....so was connected properly in the first place.

As i say it's been a while and from my short time on these forums i've come to the conclusion Tony seem's to be the Main motors guy around here.

 

[silva.foxx]

Been along time since i played with inverters but from what i remember (back in the day) an inverter throws out 3phase 240v and not 3phase 415v...

:book: an inverter connected to a 1ph 230vac supply will ouput up to 230v in 3ph arrangement.

an inverter connected to a 3ph 400vac supply will output up to 400v in 3ph arrangement.

Dual voltage motors are 230v delta / 400v star... or 400v delta / 690v star... hence why I asked what the rating plate stated on the motor.

 

[Swicade]

Ah of course...single phase and three phase inverters,my bad.
like i say been awhile hence a not too helpful post....slowly coming back to me with abit of a nudge....

 

[silva.foxx]

Ah of course...single phase and three phase inverters,my bad.
like i say been awhile hence a not too helpful post....slowly coming back to me with abit of a nudge....

Everyday is a school day!

 

[Knobhead]

Hard to give any firm advice without the rating plate details

Have a look http://www.electriciansforums.net/commercial-industrial-electrical/43777-motors.html post#5

 

[plugsandsparks]

Some things are a little puzzling. Ventilation, i.e. a Fan is not usually the most demanding of starts. . Again cannot imagine this motor is starting and stopping every minute or so, which should not really be hamering the VSD. I would check the motor windings first - oh and the bearings, could be totally coincidental.

 

[Inteificio]

If your motor is cooking and now burnt that would explain why it has trouble starting.

 

[Darkwood]

It may be the case the OP has come across a duel voltage motor which was correctly connected for star 400v (OP then connected in delta been 230v).. in doing so its possible the motor ran ok for a few weeks due to the settings on the inverter not been full speed as frequency and voltage rise as speed demand rises so it may be the case the inverter wasn't supplying full voltage letting the overvoltaged winding last longer but inevitably they have overheated and been damaged.

@ silva fox .... your inverter listing is out dated, ive fitted 110v single ph to 230v 3ph recently; yes agree sounds mind boggling how its achieved but i tell thee no lies

 

[Knobhead]

You can get two stage inverters 230V SPh to 400V 3Ph if you've got deap pockets.

 

[silva.foxx]

... @ silva foxx .... your inverter listing is out dated, ive fitted 110v single ph to 230v 3ph recently; yes agree sounds mind boggling how its achieved but i tell thee no lies

AC Inverter Drives (115V)

As said in post #14... Everyday is a school day.

Not surprised to learn of that... the amount of 1ph dual voltage equipment we have at hand where you have that little red slide toggle to choose 120 or 240 as input voltage.