BEE2123 ELECTRICAL MACHINES
Mohd Rusllim Bin Mohamed Ext: 2080 A1-E10-C09 rusllim@ump.edu.my
© MRM 05
Learning Outcomes
At the end of the lecture, student should to:
Understand the principle and the nature of static machines of transformer. Perform an analysis on transformers which their principles are basic to the understanding of electrical machines.
© MRM 05
Introduction
A transformer is a static machines. The word „transformer‟ comes form the word „transform‟. Transformer is not an energy conversion device, but is a device that changes AC electrical power at one voltage level into AC electrical power at another voltage level through the action of magnetic field, without a change in frequency. It can be either to step-up or step down.
Transmission System
TX1 TX1
Generation Station
33/13.5kV 13.5/6.6kV
Distributions
TX1
TX1
© MRM 05
6.6kV/415V Consumer
Transformer Construction
Two types of iron-core construction:
a) b)
Core - type construction Shell - type construction
Core - type construction
© MRM 05
Transformer Construction
Shell - type construction
© MRM 05
Ideal Transformer
An ideal transformer is a transformer which has no loses,
i.e. it‟s winding has no ohmic resistance, no magnetic leakage, and therefore no I2 R and core loses. However, it is impossible to realize such a transformer in practice. Yet, the approximate characteristic of ideal transformer will be used in characterized the practical transformer.
N1 : N2 I1 V1 E1 E2 I2 V2
V1 – Primary Voltage V2 – Secondary Voltage E1 – Primary induced Voltage E2 – secondary induced Voltage N1:N2 – Transformer ratio
© MRM 05
Transformer Equation
Faraday‟s Law states that, If the flux passes through a coil of wire, a voltage will be induced in the turns of wire. This voltage is directly proportional to the rate of change in the flux with respect of time.
Vind Emf ind