To provide an under-load tap switcher diagnostic apparatus and a diagnostic method which uses it, wherein the switching time of a switcher is easily and surely measured without disassembling a transformer and lifting a switcher outside of it nor fitting a special sensor inside a tap switcher under load.
An under-load tap switcher diagnostic device 21 is provided with a DC voltage source 22 for electrifying the internal circuit of an under-load tap switcher 2 with a DC current, an external connection terminal 28 for connecting the DC voltage source 22 to a bushing 5 of a transformer 1, a resistor 24 for measuring a time-base change waveform of DC current as a voltage drop, and a personal computer 27 for displaying the time-base change waveform.
MATSUI SHINICHI
OZAKI EIJI
