Register to reply

3-phase Delta Induction machine problem for Electric Machines and Power Electronics

Share this thread:
May1-11, 05:15 AM
P: 492
1. The problem statement, all variables and given/known data

A [tex]\Delta[/tex] connected induction machine is to start from a source of 480V, 60 Hz.

The motor ratings are :

4 poles, [tex]\Delta[/tex] connected, 480V, 60 Hz, [tex]X_{ls}\,=\,X_{lr}\,=\,4\,\Omega[/tex], [tex]X_m\,=\,50\,\Omega[/tex], [tex]R_s\,=\,0.25\,\Omega[/tex], [tex]R_r\,=\,0.4\,\Omega[/tex].

Find the current in the windings and the torque of the motor and the current at the line side.

2. Relevant equations

[tex]I_S\,=\,\frac{V_{l-l}}{\left(R_s\,+\,j\,X_{ls}\right)\,+\,\left(j\,X_m\,||\,R_r\,+\,j\,X_{ lr}\right)}[/tex]



Where [tex]n_{ph}[/tex] is number of stator phases.


Where p is number of poles.

The above equations are not given explicitly anywhere, but an example uses them so I think they are right.

3. The attempt at a solution

At starting, s = 1.

[tex]I_S\,=\,\frac{480}{\left(0.25\,+\,j\,4\right)\,+\,\left(j\,50\,||\,0.4\ ,+\,j\,4\right)}\,=\,62.1^{\angle\,-85.6^{\circ}}[/tex]

[tex]I_R\,=\,\left(62.1^{\angle\,-85.6^{\circ}}\right)\,\frac{j\,50}{0.4\,+j\,4\,+\,j\,50}\,=\,57.5^{\ang le\,-85.2^{\circ}}[/tex]


[tex]T\,=\,3\,\left(\frac{3967.5}{377}\right)\,\left(\frac{0.4}{1}\right)\,= \,63.14\,Nm[/tex]

Does that look right? How do I get the current at the line side?
Phys.Org News Partner Science news on
Bees able to spot which flowers offer best rewards before landing
Classic Lewis Carroll character inspires new ecological model
When cooperation counts: Researchers find sperm benefit from grouping together in mice
May1-11, 04:42 PM
P: 492
I found an equation that will possibly give line side current...


But what is [tex]I_{ph}[/tex]? Is it [tex]I_S[/tex] or [tex]I_R[/tex]?

Register to reply

Related Discussions
3 Phase Induction Machines Electrical Engineering 15
Electric machines & power electronics - PMAC machine connected in Y, 4 poles... Engineering, Comp Sci, & Technology Homework 2
Electrical Machines and Power Electronics - 3 phase, 6 pole induction motor Engineering, Comp Sci, & Technology Homework 1
3 Phase Machine Line Current problem Engineering, Comp Sci, & Technology Homework 2
Electric Power & Machines BSc .. Possible Nuclear Engineering MSc ? Academic Guidance 5