TABLE OF CONTENTS The two types of generator maintenance are on-load and off-load maintenance. The on-load maintenance consists mainly of monitoring activities. This type of maintenance is very important because it detects the conditions that could lead to a catastrophic failure.
This type of maintenance varies with the design of the machine and the instrumentation installed in it. The following paragraphs describe the standard maintenance and monitoring activities as well as the recent developments in monitoring techniques.
Temperature Measurement Thermocouples are installed in the stator to monitor the temperature of the stator bar insulation, core teeth, core end plates, stator water connections, and hydrogen gas. Eighty thermocouples are used for a typical 660-MW generator. The readings of these thermocouples are displayed in the control room. Analysis of the information obtained from them will help to identify developing faults and deficiencies in the cooling circuit and the stator.
End Winding Vibration A vibrations transducer module is installed in the end windings. It measures the vibration in all directions. It identifies deterioration in the structural integrity of the end winding and stresses in the conductor coil that approach the initiation of fatigue cracking.
Stator Water Flow The flow rate of the stator water is monitored by sight-glass indicators having a flap in the flow. The angle of the flap provides a rough indication of the flow rate. Regular monitoring of the flow rate will give an indication of a change in the flow rate that...
