A DC motor can be operated from a single-phase AC supply. The direction of the torque produced by a DC machine is determined by the direction of current flow in the armature conductors and by the polarity of the field. Torque is developed in a DC machine because the commutator arrangement permits the field and armature currents to remain in phase, thus producing torque in a constant direction. A similar result can be obtained by using an AC supply, and by connecting the armature and field windings in series.
The emitter current (IE) of a transistor has two components such as base current (IB) and collector current (IC). The base current (IB) is about 2% of the emitter current (IE), but the collector current (Ia) is about 98% of the emitter current (IE). ∴ IE > IC > IB IE = IB + IC
While estimating the overhead lines, the first and last pole is always earth connected and after every 3rd electrical pole, the fourth pole is earthed. Therefore, the approximate number of required ground set = 4
Ampere works law or Circuital Law This law relates to work done in a magnetic circuit i.e. closed magnetic flux path. The work done on or by a unit N-pole in moving once round any complete path is equal to the product of current and number of turns enclosed by that path
In terms of slip, the actual speed of the motor (N) can be expressed as N = Ns(1 − s) At start, the motor is at rest and hence its speed N is zero. s = 1 ( start) This is the maximum value of slip s possible for the induction motor which occurs at start. While s = 0 gives us N = N. which is not possible for an induction motor. So slip of the induction motor cannot be zero under any circumstances. Practically motor operates in the slip range of 0.01 to 0.05 i.e. 1 % to 5 %. The slip corresponding to the full load speed of the motor is called full load slip.
EXAMIANS
