20kHz–300kHz mechanical vibration acoustic detection is used in partial discharge detection to capture acoustic signals induced by discharge, and is particularly suitable for on-site condition assessment of equipment such as switchgear and cable terminations. The JFD-6500 partial discharge detector is designed for technical engineers in both field and laboratory scenarios. The following key application points are discussed below.
Point 1: Sensor installation position and coupling method. Acoustic signals attenuate quickly in solid media, so the sensor should be placed as close as possible to the suspected discharge location, such as the busbar compartment of switchgear or cable joints. The contact surface must be clean and flat, and an appropriate amount of couplant should be used to eliminate air gaps, avoiding loss of high-frequency components due to poor contact. For GIS equipment, the sensor can be attached to the enclosure surface, taking care to avoid structural discontinuities such as reinforcing ribs.
Point 2: Matching sampling parameters with signal characteristics. The 20kHz–300kHz acoustic signal has a wide frequency span, and a sampling rate of no less than 100MS/s is recommended to preserve high-frequency details. Sampling resolution can be selected as 8-bit, 12-bit, 14-bit, or 16-bit. For field inspections, emphasis may be placed on dynamic range and response speed, while for laboratory analysis, 14-bit or 16-bit is preferred to improve amplitude resolution. When ambient noise is high, the trigger threshold can be adjusted appropriately to filter out continuous background interference.
Point 3: Identification and recording of background noise. Before on-site measurement, background noise should first be acquired, and its amplitude and spectral distribution recorded. Discharge acoustic signals usually appear as burst pulses and differ from continuous noise such as fans and mechanical vibration in the time-domain envelope. For suspected signals, multiple measurements can be taken to observe their phase correlation and help determine the signal source.
Point 4: Ensuring data traceability. For factory tests or comparative tests with higher accuracy requirements, attention should be paid to the traceability records of the measurement system. The detector's parameter settings, sensor sensitivity curves, and calibration information should be fully archived to ensure comparability of measurement results across different batches.
