Mutual inductance between two coupled coils is given by the relation M = K√L1L2 Where L1L2 = Inductance of the coil K = Coefficient of coupling When K = 1 coils are said to be tightly coupled and if K is a fraction the coils are said to be loosely coupled. Here Kmax =1 Kmin =0 ∴ m ≤ (L1 L2 )0.5
Sudden changes of load on synchronous motors may sometimes set up oscillations that are superimposed upon the normal rotation, resulting in periodic variations of a very low frequency in speed. This effect is known as hunting or phase-swinging.
In the capacitor start, single-phase induction motor the capacitor is connected in series with the starting auxiliary winding. In this manner, the current in the starting winding may be made to lead the line voltage. Since the running winding current lags the line voltage, the phase displacement between the two currents is made to approximately 90° on starting. Placing the capacitor in the auxiliary winding circuit to produce a greater phase difference between the current in the main and the auxiliary windings. Due to greater phase difference capacitor Start motors have very high starting torque for a single-phase AC motor.
Galvanized steel conductors do not corrode, and possess high resistance. Hence such Wires are used in telecommunications circuits, earth wires, guard wire, stray wire, etc.
EXAMIANS