Apparatus and method of water absorption test for generator stator winding insulator using cross capacitance

An apparatus of water absorption for generator stator winding insulator using a cross capacitance, comprising:

• a sensor by a cross capacitance;
• and
• a water absorption testing unit for carrying out the water absorption test of the insulator of the stator winding of the power generator using the sensor, wherein the water absorption testing unit comprises:
• a relay circuit for relaying a signal between the sensor and a CPU;
• a transformer bridge for receiving a signal from the sensor through the relay circuit and branching the same;
• an oscillator connected to the transformer bridge to supply a local oscillator frequency;
• a phase shifter for shifting a phase of the signal from the sensor received from the transformer bridge by 90 degrees with reference to the frequency received from the oscillator;
• first and second amplifiers for receiving a signal detected by the sensor from the transformer bridge and amplifying the same;
• a first detector for transforming an analog signal of the sensor amplified by the first amplifier into a digital signal;
• a second detector for transforming an analog signal of the sensor amplified by the second amplifier into a digital signal required for the 90 degree phase shift by the phase shifter;
• an A/D converter for converting the analog signals of the oscillator into digital signals;
• the CPU for receiving the signals of the sensor converted into the digital signals by the first and second detectors and a reference signal from the A/D converter and for carrying out the water absorption test of the insulator of the stator winding of the generator;
• and
• an interface for connecting a main system to the water absorption testing unit.