As a non-destructive diagnostic technique,return voltage measurements based on dielectric response theory have been introduced for condition assessment of transformer insulation,especially for the evaluation of water content in transformer pressboard.

One of the methods currently being investigated as a possible non-intrusive diagnostic tool for condition monitoring of power transformer and cable is the recovery voltage measurement, which will be improving the ability of detecting the content of water concentration and the ageing process in the insulation system and may thus be an indicator of insulation quality and its ageing status.

A method for quick locating the defects in voltage circuit

The propagation of abnormal voltage signal produced by faulted CVT from one secondary voltage circuit to another in a sub- station is discussed.

In order to prevent persons and equipments from being harmed by secondary voltage circuit disconnection and inverse charge and increase the safe factor of high voltage circuit, this dissertation expounds the harm and countermeasures of the secondary voltage circuit disconnection according to the theory of secondary voltage circuit for double bus bar substation.

When E3 is an alternating field, a steady asymmetrical piezoelectric loop is observed.