ENEE473 Lab 6 Report

ENEE473 Lab 6 Report - Scott R. Smith ENEE473 Lab 6:...

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Scott R. Smith ENEE473 Lab 6: Three-Phase Induction Machine Mechanical Characteristics March 16, 2007 Purpose: This experiment will allow me to determine the physical characteristics for the three- phase induction machine. 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 achieve the same value as a series connection would. 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 machine are 1 kW , 208 V , 6.2 A , and 1770 RPM . DC Dynamometer – The DC dynamometer (DCD) is a direct current machine. It can be mechanically coupled to the IM using plastic pins and collars. The DCD can be used to measure torque, lock the rotor, be a prime mover, and act as a mechanical load. The rating of the DCD is 1 kW .
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Experimental Procedure: I. Motor Regime Testing 1. Mechanically couple the IM and the DCD. Insert the plastic pins and tighten the collar between the IM and DCD. Make sure the synchronous machine is decoupled from the DCD. 2.
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ENEE473 Lab 6 Report - Scott R. Smith ENEE473 Lab 6:...

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