Moisture Analysis By FDS & PDC
Omicron Dirana
Dielectric Frequency Response (DFR)
A large population of aged equipment is apparently contaminated with moisture. Effects on life of Power transformer due to moisture in the solid insulation are:
- Accelerated rate of aging for cellulosic materials such as paper and press board
- Reduction of the dielectric strength of paper and press board materials
- Risk of bubble evolution at high temperatures and limited Overloading capacity.
- Moisture content in the oil/paper insulation
- Faults in OIP, RBP and RIP high voltage bushings & CT
- Faults in the generator, motor and cable insulation
- Monitoring of moisture content in solid insulation during maintenance actions such as On-site drying will be very
Now a days two approaches are applied; the measurement of charging and discharging currents in time domain (Polarization and Depolarization Currents PDC) and the dielectric spectroscopy in frequency domain (Frequency Domain Spectroscopy FDS) & provides an indication of the insulation condition such as:
