When there is no mutual flux between two coils, they are said to be magnetically isolated. In this case. k = 0 and M = 0.
A single-phase induction motor with only one winding on the stator cannot produce any starting torque. Hence, some extra arrangement is required to start the motor. In the running condition, the motor is capable of developing the torque with only one winding on the stator.
The simplest method of starting is to provide an auxiliary winding on the stator in addition to the main winding. The two windings are placed in the stator with their axes displaced by 90 electrical degrees in space.
Voltage Scale Span of instrument = Vmax − Vmin
Vmax = 5 V
Vmin = −5V
Span = 5 −(−5) = 10 V
In the same way that we can have series, parallel or series-parallel electric circuits, we can also have equivalent series and series-parallel (but not parallel) magnetic circuits.
In practice, a magnetic circuit may consist of several parts in a series of different lengths, cross-sectional areas, and permeabilities. In such a series magnetic circuits, all the reluctances of several parts will get summed up together (as resistors in an electric circuit) to form the net reluctance of the circuit.
In series magnetic circuits the flux passing through each part will be the same (as current in the series electric circuits).
According to Kirchhoff’s law states that the current entering a node is always equal to the current leaving a node.
From the above Diagram
Current Flowing towards the Point: I1, I2, I6
Current Flowing Away from the Point: I3, I4, I5
Hence I1 + I2 + I6 = I3 + I4+ I5