ENEE473 Lab 5 Report

# ENEE473 Lab 5 Report - Scott R. Smith ENEE473 Lab 5:...

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Scott R. Smith ENEE473 Lab 5: Three-Phase Induction Machine Equivalent Circuit Model March 9, 2007 Purpose: This experiment will allow me to determine the equivalent circuit model parameters for the three-phase induction machine. The equivalent circuit is shown below in figure 1. 1 R eq x 1 ˆ I 2 ˆ I s R 2 1 ˆ V e R m x 11 Figure 1 Parameter Description: 1 ˆ I the current through one phase of the stator windings 2 ˆ I the current through one phase of the rotor windings 1 ˆ V the voltage applied to one phase of the stator eq R the heating losses due to eddy currents m x 11 the mutual reactance linking the stator and rotor () + = l l eq x x x 2 1 the leakage reactance from the stator and rotor 1 R the resistance of one phase of the stator windings s R 2 the resistance of the rotor Devices and Instrumentation: Resistor Banks – Each bank of resistors is made up of ten individual resistors that can be connected together using single pole double throw switches. By systematically setting the switches it is possible to create many resistance values by combining series and parallel branches in one bank. Each resistor has a power dissipation rating of 100 W and a resistance value of 250 . The power dissipation capacity can be increased by using parallel branches of resistors to

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Transformer – There are three single-phase step-up transformers in the lab station. Each transformer is rated at 1 kW . The primary is on the left and secondary on the right. The single- phase transformer uses two coils (one primary and one secondary) that are coupled my a magnetic circuit through a core. The turn ratio determines the difference in input voltage and output voltage. Wattmeter – The wattmeter is a three-terminal device where two terminals are connected in-line with the circuit to measure current and the third terminal measures voltage of the in-line voltage relative to the connected node. There are two wattmeters at the lab station. Using both of them, three-phase power can be measured. Three-Phase Induction Machine – The induction machine (IM) is very similar to a transformer with the secondary winding shorted. I am assuming that the induction machine is viewed as a balanced Y load. The stator has three-phase windings distributed in space and time by 120 degrees. When the three-phase windings are excited from a three-phase source a rotating magnetic field is created. The rotating field interacts with the rotor by inducing a voltage across the bars in the rotor. The induced voltage creates current in the rotor which lags the voltage applied to the stator. The rotor current produces a rotor reaction magnetic field which interacts with the stator magnetic field. The rotor field continuously tries to align with the stator field. Torque is produced because the rotor reaction field always lags the stator field. The ratings of the
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## This note was uploaded on 05/04/2008 for the course ENEE 473 taught by Professor Mayergoyz during the Spring '07 term at Maryland.

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ENEE473 Lab 5 Report - Scott R. Smith ENEE473 Lab 5:...

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