In a capacitance graded bushing, the test tap is a component which main purpose is to provide access to measure the bushing capacitance and power factor. The voltage tap, in addition, can be used for permanent voltage measurement or online monitoring of PF or partial discharge.
The Bushing Potential Devices of Hitachi Energy are capacitive voltage dividers that connect to the voltage tap of the condenser bushing. They use the bushing’s capacitance and its own capacitors and inductors to provide an output voltage that is proportional to and in phase with the bushing line-to-ground voltage. Learn more.
Lower but still high voltage bushings will not have a C2 capacitor and will be hence called a Test Tap. Important components include: A draw lead which allows connection from a single phase to the lead of the winding within the Transformer’s tank. The Capacitor layers are previously discussed and described above.
The Bushing Potential Device of Hitachi Energy is a capacitive voltage divider, which connects to the voltage tap of the condenser bushing. It uses the bushing’s capacitance and its own capacitors and inductors to provide an output voltage, which is proportional to and in phase with the bushing line-to-ground voltage.
Typical configuration of a capacitor bushing. [...] In high-voltage capacitor bushings, there is maximum field intensity at the edge of the aluminum foil and where foils overlap. Any technique decreasing much field intensity in those regions will significantly optimize the bushings' electrostatic characteristics.
OIP bushings are designed as a capacitive divider with many capacitors, grouped by a tap connection, in two main capacitances or as two capacitors C1 and C2, which values are usually indicated by the manufacturer on the bushing nameplate. The tap connection, depending on its constructive characteristic, is classified as a test tap or a voltage tap.