Online monitor apparatus for partial discharge of transformer

The utility model discloses an online monitor apparatus for the partial discharge of a transformer, which comprises a high frequency current transformer and an ultrahigh frequency sensor installed on a grounded wire of a power transformer core, a casing or a clamper, and a monitor device connected with signal output ends of the high frequency current transformer and the ultrahigh frequency sensor, wherein the monitor device comprises a detector, an analog-digital converter and a signal analyzer. In the online monitor apparatus, the high frequency current transformer and the ultrahigh frequency sensor are mounted on the core grounded wire of the core, the casing or the clamper to monitor discharge, so the power transformer is structurally unchanged and convenient for installation, furthermore, the online monitor apparatus has high monitor sensitivity and strong resistance to electromagnetic interference.