The high voltage dielectric loss tester is an indispensable tool for insulation preventive testing and condition maintenance of modern power equipment. Its core value lies in the use of cross frequency testing technology, which effectively overcomes strong power frequency on-site interference and achieves high-precision and high stability measurement of the key insulation parameter of dielectric loss factor. By regularly measuring the trends of tan δ and Cx, potential hazards such as early moisture and deterioration of equipment insulation can be identified in a timely manner, and the insulation condition can be evaluated. This provides important basis for equipment operation, maintenance, and repair decisions, and is of great significance for ensuring the safe and reliable operation of the power system.
Overview of Working Principle
1. Signal source: The internal inverter converts DC or low-voltage AC power into a high-voltage sine wave AC test voltage of the desired frequency (out of frequency).
2. Apply voltage: Apply high voltage test voltage to the tested equipment through high voltage leads.
3. Signal acquisition: Use high-precision sensors (voltage transformer PT, current transformer CT, or sampling resistor) to simultaneously collect the voltage signal applied to the sample and the current signal flowing through the sample.
4. Phase difference measurement: The core lies in accurately measuring the phase difference angle δ between the voltage signal and the current signal. tan δ=tan (90 ° - φ) ≈ δ (when δ is small), where φ is the power factor angle.
5. Computational processing: The high-speed A/D converter digitizes the analog signal, and the internal microprocessor uses digital signal processing techniques (such as FFT and related algorithms) to calculate the amplitude of voltage and current, as well as the phase difference δ between them, in order to calculate tan δ. Simultaneously calculate the capacitance Cx based on the amplitude of voltage and current.
6. Anti interference processing: Utilizing the advantages of different frequencies, algorithms such as digital filtering, multiple measurement averaging, and vector operations are used to filter out or cancel out the impact of power frequency interference signals.
7. Result display and storage: Display the calculation results (tan δ, Cx) and test conditions (voltage, frequency, time, etc.) on the screen and store them in internal memory or output.