A device for detecting multipoint earthing of a
voltage transformer for an electric
system comprises a CPU main controller, an analog-
digital conversion circuit and a switch
control circuit. A
voltage transformer secondary
neutral line N600 penetrating into an opening current transformeris connected with a ground point, and output passes through a first filter amplifying circuit to the analog-to-
digital conversion circuit. A ground point penetrates through a
current transformer to be connected with one end of a sampling
resistor Rv, output passes through a second filter amplifying circuit to reach the analog-to-
digital conversion circuit, the other end of the sampling
resistor Rv is connected with a plurality of
branch circuits, and switches and resistors are in series connection with the
branch circuits which are correspondingly and externally connected with an A-phase bonding post of the
voltage transformer for
electricity use. The two ends of the sampling
resistor Rv further outputs a 0-5V voltage
signal to the analog-to-digital conversion circuit through an isolation amplifying circuit. The invention further relates to a method for detecting multipoint earthing faults of the voltage transformer for the electric
system. According to the device for detecting multipoint earthing of the voltage transformer for the electric
system and the method for detecting multipoint earthing faults of the voltage transformer for the electric system, whether the multipoint earthing faults of many voltage transformers exist can be accurately detected in time, and the multipoint earthing faults can be specifically located.