How to effectively discriminate the quality of anti-interference dielectric loss tester

working principle:

Under the action of AC voltage, the dielectric consumes some electric energy, and this part of electric energy will be converted into heat energy to generate losses. This loss of energy is called dielectric loss. When the AC voltage is applied to the dielectric, there is a phase angle difference between the voltage and the current in the dielectric. The residual angle δ of the Ψ is called the dielectric loss angle, and the tangent tδ of the δ is called the dielectric loss tangent. The tgδ value is a parameter used to measure the dielectric loss. The instrument measurement circuit includes a standard loop (Cn) and a tested loop (Cx) as shown in FIG. The standard loop consists of a built-in high-stability standard capacitor and a measurement circuit. The circuit to be tested consists of the test object and the measurement circuit. The measurement line consists of a sampling resistor, a preamplifier, and an A/D converter. The measurement circuit separately measures the standard loop current and the current amplitude and phase of the circuit under test, and then the microcontroller uses a digital real-time acquisition method to calculate the capacitance value and the dielectric loss tangent of the sample through vector operations.

Internal anti-interference measures have been adopted to ensure accurate measurement under external electric field interference. Control panel: printer, keyboard, display and communication relay. Variable frequency power supply: The SPWM switching circuit generates high-power sine wave voltage regulator output.

Step-up transformer: The output of the variable frequency power supply is boosted to the measurement voltage, and the maximum reactive output is 2 KVA/1 minute.

Standard capacitor: Internal Cn, measurement reference.

Cn current detection: used to detect the standard capacitor current, 10μA ~ 1A. Input resistance <2Ω.

Cx positive wiring current detection: only for positive wiring measurement, 10μA～1A. Input resistance <2Ω. Cx reverse wiring current detection: only for anti-wiring measurement, 10μA ~ 1A. Input resistance <2Ω.

Anti-wiring digital isolation communication: using precision MPPM digital modem, will reverse wiring current signal

Send to the low pressure side. Isolation voltage 20KV.

Instructions:

After starting the measurement, the high voltage setting value is sent to the variable frequency power supply, and the variable frequency power supply uses the PID algorithm to adjust the output to the set value in a slow manner. The measurement circuit will send the measured high voltage to the variable frequency power supply, fine-tune the low voltage, and achieve accurate high voltage output. According to the positive/reverse wiring setting, the measuring circuit automatically selects the input and switches the range according to the test current. The measurement circuit uses the Fourier transform to filter out the interference, separates the signal fundamental wave, performs vector operations on the standard current and the sample current, and calculates the amplitude. The angle difference calculates tgδ. Repeat the measurement several times and select an intermediate result after sorting. At the end of the measurement, the measuring circuit sends a step-down command to reduce the frequency of the power supply to 0.

Parameters :

1. High voltage output:

0.5～10kV, 500V increase per gear, ten gears, capacity: 1000VA

2. Accuracy:

Tgδ: ± (read *1.0%+0.08%)

Cx: ± (read *1.5%+5PF)

3. Resolution: tgδ: 0.01% Cx: 1pF

4. Measurement range: 0.1% < tgδ < 50%

3PF< Cx < 60000PF

10kV, Cx≤30000PF

5kV, Cx≤60000PF

5. Power Supply: AC 220V ± 10% 50 ± 1Hz

6. Power Harmonic Adaptability: ≤3%

7. Conditions of Use: -15°C-50°C Relative Humidity <80%

8. Dimensions: 460 (L) × 335 (W) × 340 (H)

9. Weight: 30 kg