Question
Download Solution PDFHow to extract maximum torque in a single phase repulsion type motor?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFRepulsion Motor: It is a special kind of single-phase AC motor which works due to the repulsion of similar poles. The stator of this motor is supplied with a single-phase AC supply and the rotor circuit is shorted through a carbon brush.
The torque in the repulsion motor is given as
Te = 0.5k Is2 Ns2 sin 2α
Where Is and Ns are the stator filed-current and an effective number of stator turns.
α is the angle between the brush axis or rotor field axis to the stator field axis.
Since a constant stator field motor extract maximum torque when
sin 2α = 1 ⇒ 2α = 90° ⇒ α = 45°
Maximum torque in the repulsion motor is achieved when the stator and rotor field axis is 45° apart.
Important Points
| Rotor current is maximum when the brush axis and direct axis coincide(α = 0°) | Rotor current is zero when the brush occupies a position in quadrature with the direct axis(α = 90°) |
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