A partial discharge tester is an instrument specifically designed to detect partial discharge phenomena in power equipment. Partial Discharge (PD) refers to the discharge phenomenon that occurs in local areas within the insulation system of power equipment, which is often an early sign of insulation material degradation. The partial discharge tester helps power engineers detect hidden dangers in equipment in a timely manner and prevent failures. This article will provide a detailed introduction to the working principle, usage steps, and importance of the partial discharge tester.
Working Principle
The working principle of the partial discharge tester is based on the detection of electromagnetic field changes generated during the partial discharge process. When partial discharge occurs, it is accompanied by the emission of electromagnetic waves. These signals are captured by specific sensors, then processed through pre-processing steps such as amplification and filtering, and finally presented through a display unit.
Specifically, when partial discharge occurs under the test voltage, the pulse control signal of the partial discharge detector will be discharged through the system coupling capacitor and sent to the input data unit. Then, through the information input unit, the pulse signal pickup is amplified by a low-noise amplifier to enhance the pulse signal. In the filter amplifier, the desired frequency band is selected, and after the main amplifier amplifies the effect, the required pair of values and zero marker pulses are achieved. Above the elliptical scanning baseline on the oscilloscope screen, visible discharge pulses will be generated. They will also be sent to the pulse peak value, and its peak value can also be displayed. The time window unit within the system controls the test voltage and displays the working time of the pulse peak meter weekly. During this period, the corresponding display area can also be highlighted on the oscilloscope screen to eliminate interference from fixed phases.
Usage Steps
Here are the basic steps for using the partial discharge tester:
Startup Preparation: Ensure the instrument is properly grounded, connect to a 220V power supply, and set the display mode to "Ellipse" (default).
Discharge Calibration: Before applying the test voltage, use the calibration pulse generator for calibration to ensure measurement accuracy.
Adjust Gain: Adjust the amplifier gain knob so that the height of the injected pulse is appropriate (about 2 cm on the oscilloscope screen), making the digital voltmeter reading match the known injected charge. After adjustment, keep the fine adjustment knob position of the amplifier unchanged.
Remove Calibrator: Disconnect the calibration pulse generator from the test circuit.
Test Operation: Turn on the high-voltage test circuit power, slowly increase the test voltage, and note the first occurrence of continuous discharge. When the discharge amount exceeds the specified minimum value, the voltage at that time is the partial discharge inception voltage. By operating the "Starting Phase Selection" (ellipse rotation) button switch, place the discharge signal at the most favorable position for observation on the ellipse.
Importance
The partial discharge tester is crucial for the maintenance of power equipment because it helps to:
Early Warning: Detect problems in advance by detecting partial discharge before failures occur.
Preventive Maintenance: Develop reasonable maintenance plans based on test results to reduce equipment failure rates.
Fault Diagnosis: Assist engineers in quickly locating problems and reducing downtime.
Quality Control: Used for quality control and performance verification during the production of power equipment.
Conclusion
The partial discharge tester is a very important testing tool in the power industry. It can timely detect potential problems in the internal insulation system of power equipment and effectively prevent major accidents. With continuous technological advancements, future partial discharge testers will become more intelligent and portable, bringing more convenience to the operation and maintenance work of the power industry.
The above is a detailed introduction to the partial discharge tester. I hope this article can provide you with relevant information and technical details about the partial discharge tester. If you need more detailed information or specific case analysis, please feel free to let us know.
