The TZY-PDM-K high-voltage switchgear partial discharge online monitoring system obtains real-time partial discharge volume and environmental temperature and humidity (optional) under the operation status of the switchgear. Through comprehensive analysis of various dynamic and static data, it provides user guidance and analysis conclusions, which can provide strong support for intelligent operation and maintenance of high-voltage switchgear. The sensor is a two in one composite sensor that can simultaneously monitor ultrasonic and transient low voltage signals of partial discharge. Using an insulated shell with a thickness of only 40mm, and adopting an adsorption installation method, it does not affect the mechanical structure and insulation performance of the equipment.

1、Principle of transient ground voltage monitoring

When partial discharge activity occurs in a high-voltage switchgear, it generates electromagnetic waves in the radio frequency range, which can leak from inside the switchgear to the outer surface through openings in the metal casing. These openings can be gaps around the casing, sealing gasket, or other insulating components. When electromagnetic waves propagate outside the switchgear, they will generate transient voltage to ground on the grounded metal casing. Transient Earth Voltage (TEV) exists in the range of several millivolts to several volts for a short period of time, with a rise time of several nanoseconds. The probe can be placed on the surface of the switchgear while it is in operation, using this non-invasive method to detect partial discharge activity.

2、Principle of Ultrasonic Monitoring

When a partial discharge occurs in a medium, the energy released instantly causes violent collisions between molecules, and macroscopically forms a pressure that generates ultrasonic pulses. At this time, the partial discharge source acts as a sound source, emitting ultrasonic waves outward. Due to the short duration of discharge, the frequency spectrum of the emitted sound source is wide, reaching several hundred kilohertz. In addition, due to the short wavelength of ultrasonic waves, its directionality is strong, resulting in more concentrated energy. Effective ultrasonic signals can be detected from the gaps in the switchgear for diagnosis of partial discharge.

The switchgear partial discharge monitoring device consists of intelligent sensors and data receiving terminals. One data receiving terminal can connect up to 240 intelligent sensors. Install one intelligent sensor on each switchgear to monitor the partial discharge status inside the cabinet; The data receiving terminal receives monitoring data from all sensors in the distribution room through LoRa wireless transmission technology, and connects to the user's main monitoring system through RS485 bus or uploads it to the cloud platform server through 4G network for remote diagnosis and viewing.