Thursday, December 25, 2014

Three Phase Induction Motor

UNDER EDITING

Students should be able to perform the following:

A- explain the construction of the ac induction motor.
B- explain the concept of rotating field and how it is created.
C- explain the working of the rotor
D- calculate the speed of rotating field .
E- calculate slip speed ans speed of the rotor


Many of my students find it difficult to understand the AC induction motors.

It does not matter whether it is 3 phases or 2 phase motor, because the principle is the same.

It needs the understanding of 2 concepts:

- the rotating magnetic field
- the rotor

It is the interaction of the rotating field and the rotor will cause the rotor to rotate.

B. Creation Of Rotating Field
This is better explained by video used by this video



Monday, December 22, 2014

DC Generator Overhaul


UNDER  EDITING




Testing The Armature
There are 2 basic test:
- Using meter
- Using Growler

1. Test Using Gowler
Growler is like the primary winding of a transformer. When the armature is positioned on the growler, the armature is acting like the secondary of the transformer. However, please take note that the secondary winding of the armature is open circuit, so no current flows in the armature windings but there are the induced voltage

a. Check for short circuit.