Suppose we hook up an AC generator to a solenoid so that the wire in the solenoid carries AC. Call this solenoid the primary coil. Next place a second solenoid connected to an AC voltmeter near the primary coil so that it is coaxial with the primary coil. Call this
Year: 2013
Since the equivalent circuit contains two winding resistances and a core-loss resistance then power is lost as heating energy inside the transformer. Hence the conversion of power through the transformer cannot be 100%, a small loss of efficiency occurs. This is usually less than about 2% for power transformers. Assume
A single-phase power system transformer consists basically of two windings wound onto an iron core. The iron core concentrates the flux and restricts it to a defined path. It also creates the maximum possible amount of flux for a given excitation. In order to maximize the mutual coupling the two
When the maximum kW rating of an induction motor is reached for direct-on-line starting, it becomes necessary to introduce an alternative method of starting the motor. There are several methods used in the oil industry. The object is to reduce the starting current drawn from the supply during all or
There are two important time periods that are critical in the application of induction motors. One is the allowable run-up or starting time and the other is the maximum stalling time. The run-up time is determined by the static torque versus speed characteristic, and the moment of inertia of the
Induction motors have two main components, the stator and the rotor. The stator carries a three-phase winding that receives power from the supply. The rotor carries a winding that is in the form of a set of single-bar conductors placed in slots just below the surface of the rotor. The
Main Exciter The exciter (sometimes called the main exciter) is a synchronous generator that has its stator and rotor windings inverted. Its field winding is fixed in the stator, and the rotor carries the armature or AC . In addition the rotor carries the semiconductor bridge rectifier that converts the
Following phasor is phsor diagram of a two-axis salient pole generator. The following points apply to the drawing of phasor diagrams of generators and motors:- • The terminal voltage V is the reference phasor and is drawn horizontally. • The emf E lies along the pole axis of the rotor.
The stator, also called the armature, carries the three-phase AC winding. The rotor, also called the field, carries the DC excitation or field winding. The field winding therefore rotates at the shaft speed and sets up the main magnetic flux in the machine. The fundamental magnetic action between the stator
Again assume that the generator is loaded and operating in a steady state. In this situation the magnitude of the stator current is allowed to change rapidly, as in the case of a short circuit in the stator circuit. The additional flux produced by the stator winding will try to
