The dielectric loss parameter tester is mainly used to test the overall moisture, deterioration, and local defects of insulation in high-voltage electrical equipment. It is widely applied in electrical manufacturing, electrical equipment installation, handover, and preventive tests, and has significant practical value. However, before actually using the dielectric loss parameter tester, power workers need to familiarize themselves with the main hardware components and working principles of the equipment, so that they can use it more proficiently in practice. Therefore, Yitiancheng Electric takes the YTC309fully automatic anti-interference dielectric loss tester as an example to briefly explain the main structure and working principle of the dielectric loss parameter tester.
Instrument structure of the dielectric loss parameter tester:
Measurement circuit: performs all calculations such as Fourier transform, complex number operations, range switching, and variable frequency power supply control.
Control panel: printer, keyboard, display, and communication relay.
Variable frequency power supply: uses SPWM switching circuit to produce high-power sine wave regulated output.
Step-up transformer: boosts the variable frequency power supply output to the measurement voltage, with a maximum reactive power output of 2KVA/1 minute.
Standard capacitor: internal Cn, measurement reference.
CN current detection: used to detect the current of the internal standard capacitor, 10μA～1A, input resistance <2Ω.
Cx positive wiring current detection: only used for positive wiring measurement, 10μA～1A, input resistance <2Ω.
Cx reverse wiring current detection: only used for reverse wiring measurement, 10μA～1A, input resistance <2Ω.
Reverse wiring digital isolation communication: isolation voltage 20kV, uses precision MPPM digital modulation demodulator to send the reverse wiring current signal to the low-voltage side.
Working principle of the dielectric loss parameter tester:
After starting the measurement, the high-voltage set value is sent to the variable frequency power supply, which uses the PID algorithm to slowly adjust the output to the set value. The measurement circuit sends the actual high voltage to the variable frequency power supply, fine-tunes the low voltage, and achieves accurate high-voltage output. According to the positive/reverse wiring settings, the measurement circuit automatically selects the input and switches the range based on the test current. The measurement circuit uses Fourier transform to filter out interference, separates the fundamental wave of the signal, performs vector operations on the standard current and the test current, calculates the capacitance from the amplitude, and calculates tgδ from the phase difference. Multiple measurements are repeated, and a middle result is selected after sorting. At the end of the measurement, the measurement circuit issues a step-down command, and the variable frequency power supply slowly reduces the voltage to 0V.
As a high-voltage electrical test equipment frequently used by power workers, the dielectric loss parameter tester has a relatively high test voltage and a more complex usage process. Therefore, in actual work, power workers should first read the product instruction manual carefully and conduct tests strictly according to the manual. At the same time, they should be familiar with the working principle and basic structure of the equipment to achieve the test accuracy the instrument should have.
