ok so i have been readin up about AC squirrel cage motors . I am really confused as to the connections used for these motors .When do i use star connection and when do i use delta connection ? And how do i see from a motor's information plate which connection should i use . And if a motor is to be connected in star if i change it to delta will the motor be blown up ?

 

It depends on the individual motor how it is intended to be used, but generally the motor is dual voltage, e.g. 220/350 and the Star connection would be for the higher voltage and the Delta for the lower voltage.
It should be labeled at the connections something like U1 V1 W1 & U2 V2 W2 the three sets of windings.
http://www.usmotors.com/Connections/Connections.htm
Max.

 

Is there any difference in motor speed rpm in star and delta connections ?

 

Is there any difference in motor speed rpm in star and delta connections ?

No. The speed is determined by the line frequency and the number of motor poles ( with it being slightly affected by the load).

 

RPM is 60 x Hz/#pole pairs. e.g. 60x60Hz/1pp = 3600-slip frequency =~ 3520 rpm.
Max.

 

Thanks for the answers so far .

One last question . For the motor plate attached below . Can i know if i can connect both y and delta connection ?

 

380v in Delta, 440v/480v in Star.
One or the other.
Max.

 

Thanks for the answers so far .

One last question . For the motor plate attached below . Can i know if i can connect both y and delta connection ?

Yes - the nameplate is showing both connections are possible. You connect the links on the terminal block as shown in the diagram for either case. You have to also take note of the rated voltages in each case.

 

If the power coming from my country is a 3 pin plug 240v . Does means in 3 phase i get 360v and should connect in delta ?

 

My next question is - "Are you a licensed electrician in your country?"

If not, then unfortunately our conversation is concluded.

 

You would need to supply more information on the type of supply you have, if it is a residential supply it is most likely 240v 1phase neutral and ground, if so the 3 phase would be 408v .
You can run a motor from a VFD, this converts the 1phase to 3ph for motor control, but 240v will be too low for that motor.
Max.

 

I am not an electrican. My degree is in chemical engineering . Thus i know nuts about electrical engineering . Tried to google but still unsure .

Anyway may i know how is the calculation for 3phase voltage .

Oh and yes its 240v output from the socket .

Thank you.

 

Here you go.
http://www.epemag.net/electricity-generation6.html
If you have the same supply as the UK for e.g. you have one phase and a star point neutral for 240v 1ph supply.
Max.