ENEE473 Lab 11 Report

ENEE473 Lab 11 Report - Scott R. Smith ENEE473 Lab 11:...

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Scott R. Smith ENEE473 Lab 11: Parallel Operation of the Synchronous Generator (Synchronizing to the Power Line) April 27, 2007 Purpose: Electrical power is generated in multiple locations on the power grid. A synchronous generator must be synchronized to the power grid prior to being connected. There are several considerations that must be addressed to synchronize the generator to the power grid. The phase sequence must match. The voltage magnitudes must match. Since the power grid is much larger and assumed to be an infinite source/sink, if any of the above considerations is not met, the synchronous generator can be damaged by the forces placed on it from the power grid. After all the considerations are met, the speed of the generator should be adjusted to slightly above or below n syn so that the generator has a relative speed to the power grid. Once the angle of like phases must is matched, the generator may be connected to the power grid. After connection, the synchronous generator speed is locked in at n syn . 1 SM P A I A V ˆ B V ˆ A Shunt Armature AB V shunt V Synchroscope B CB V C V ˆ SM DCD C C I SM P 2 CB V Armature arm V Field sync V Mechanical Coupling f I f V Figure 1 Devices and Instrumentation: Analog Meter – This meter is very useful for watching changes in voltage or current. It is used in this lab as a synchronization tool. 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 . Multimeter – The multimeter will mainly be used to check actual resistance values and measure voltages. Synchroscope – The synchroscope, pictured below in figure 2, is composed of three lights and six inputs. Each light are exposed to the voltage difference between the input above and below it. In this fashion, the light shows the phase difference between the two sources
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connected above and below it. The synchroscope can be used to determine if phase sequences match between the three-phase input above and below. When all lights blink in unison, then the phase sequence is the same. If each light blinks individually, then the phase sequence does not match. Figure 2 Three-Phase Synchronous Machine – The three-phase SM operates at n syn unlike the induction machine. This machine is most useful as a generator of electric energy. The SM is driven by a prime mover. In our lab, the prime mover is the DCD. In most real cases, the prime mover is a diesel engine. When the SM is operated as a motor, it also runs at n syn because of the DC excitation of the rotor. The DC field in the rotor forces the rotor to spin in sync with the stator field. The SM can be started inductively as a motor. The SM is rated at 1 kW . Wattmeter
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ENEE473 Lab 11 Report - Scott R. Smith ENEE473 Lab 11:...

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