PDC Analysis on Transformer Bushings
A failure of transformer accessories such as condenser bushings sometimes leads to a transformer failure and long-term outage. Often, moisture is a cause of explosion for service-aged bushings. On-line monitoring of insulation dryness in bushings through oil analysis is a difficult task and may not represent the moisture in the paper. In addition, moisture in solid insulation cannot be detected by conventional on-site Power Factor (or DLA) Test using the frequency of 50 Hz.
Click here to download the paper presented in ISEI-2004 which includes some PDC results on transformer bushings, connection details and factors which lead to successful measurement.
The figure below shows the PDC Evaluation of Capacitance for three identical bushings – OIP-02A, OIP-02B and OIP-02C. When the insulation is dry, the capacitance is constant from 1 Hz down to low and very low frequencies such as in the case of bushing OIP-02B. Moisture in solid insulation largely increases the capacitance of the other two bushings at low and very low frequencies.
Click here to download the paper presented in ISEI-2004 which includes some PDC results on transformer bushings, connection details and factors which lead to successful measurement.
The figure below shows the PDC Evaluation of Capacitance for three identical bushings – OIP-02A, OIP-02B and OIP-02C. When the insulation is dry, the capacitance is constant from 1 Hz down to low and very low frequencies such as in the case of bushing OIP-02B. Moisture in solid insulation largely increases the capacitance of the other two bushings at low and very low frequencies.