When partial discharge occurs under the test voltage, a pulse current is generated through the coupling capacitor Ck, and the pulse signal is picked up by the input unit. After low-noise preamplifier, filter amplifier selection of the required frequency band, and main discharge amplification, the discharge pulse is displayed on the elliptical scanning baseline of the oscilloscope screen, and also sent to the pulse peak table (logarithmic table) to display its peak value. The time window unit controls the working time of the pulse peak meter during each cycle of the test voltage, and during this period, the display screen is highlighted. The width and position can be changed, further enhancing the anti-interference ability. Adopting advanced anti-interference components and * gate display circuits, and equipped with four high-frequency elliptical scans, it is suitable for the type and factory testing of high-voltage products, new product development testing, quantitative testing of partial discharge in motors, transformers, cables, bushings, capacitors, transformers, lightning arresters, switches, and other high-voltage electrical appliances. Can be used on-site by manufacturing plants, research departments, and power departments