When conducting on-site partial discharge surveys of high-voltage equipment, engineers often face a contradiction: the ultrasonic method is more sensitive to free particles and surface discharge but insensitive to internal discharge; the ultra-high frequency (UHF) method can capture discharge signals inside GIS but makes it difficult to determine which phase or which gas compartment the discharge is located in. The amplitude or spectrum obtained by a single detection method is often insufficient to support defect characterization. The JFD-9100 partial discharge detector integrates transient earth voltage (TEV), ultrasonic, and UHF sensing channels into the same acquisition host, synchronously recording multiple signals in a single inspection, facilitating cross-comparison from the relationship between signal timing and amplitude.
The three sensing signals enter the same acquisition clock, with time deviation controlled at the microsecond level. When discharge occurs inside the equipment, the UHF channel first captures the electromagnetic pulse, and the ultrasonic channel subsequently records the arrival of the acoustic wave; the time delay difference between the two signals can assist in determining the distance range between the discharge source and the sensor. For structures such as switchgear, the combination of the TEV channel and the ultrasonic channel helps distinguish internal discharge from external interference. The instrument has built-in filtering and pulse discrimination functions, which can mark and eliminate periodic communication interference and fluorescent lamp startup interference, reducing misjudgment.
Detection frequency bands: ultrasonic 20 kHz–300 kHz; UHF 300 MHz–1.5 GHz; TEV 3 MHz–100 MHz. Ultrasonic sensitivity no greater than 5 pC (laboratory conditions), UHF equivalent sensitivity no greater than 10 pC. Maximum sampling rate 1 GS/s, single recording duration configurable. The host is equipped with a color LCD screen, supports spectrum playback and data export, and the storage capacity meets continuous multi-day inspection records. Power is supplied by a built-in lithium battery, and a single charge can support one working day of on-site inspection.
Suitable for live inspection of 10 kV–500 kV switchgear, GIS combined electrical apparatus, transformer bushings, and cable terminations. For equipment in operation, preliminary screening can be completed without interrupting power supply; for suspected defect points, focused re-testing can be performed in combination with multi-channel signal characteristics, and reference locations can be provided for subsequent offline diagnostic tests. The instrument supports export of inspection reports, facilitating archiving of operation and maintenance records.
