Industrial Resistivity Meter

Overview

Integrated Precision Oil Dielectric Loss Volume Resistivity TesterThis high-precision integrated structure instrument is designed for testing the dielectric loss angle and volume resistivity of insulating liquids such as insulating oil. It internally incorporates key components such as the dielectric loss oil cup, temperature controller, temperature sensor, dielectric loss test bridge, AC test power supply, standard capacitor, high-impedance meter, and DC high-voltage source. The heating section utilizes the advanced high-frequency induction heating method, which offers non-contact between the oil cup and heating element, even heating, fast speed, and easy control. The AC test power supplyAC-DC-ACThe instrument effectively avoids the impact of voltage and frequency fluctuations from the city power supply on the accuracy of dielectric loss tests, even when the generator is providing power. The internal standard capacitor isSF6The inflatable three-pole capacitor maintains consistent precision over time, as its dielectric loss and capacitance are unaffected by environmental factors such as temperature and humidity.

The instrument employs full digital technology internally, featuring fully automated measurements with multiple modes, and is equipped with a large screen.320×240Touchscreen display, full Chinese menu, with Chinese prompts for every step, test results can be printed out, and operators can master the operation without professional training.

Operation Principle

Heating

The instrument utilizes a high-frequency induction furnace for heating. After initiating the heating process, temperature controlCPUInitiate heating command while collecting the temperature values from the internal oil cup temperature sensor, employing variable power control for heating.PWMA combination of control methods is employed. When the oil sample temperature is low, a high-power heating method is used, which helps to shorten the heating time of the oil sample; as the temperature rises to near the set temperature, a lower power is adopted.PWMThe heating method ensures even heating of the oil samples.

High-frequency induction furnace heating eliminates the issue of uneven heating of the heating block.

Temperature Control

As the measured temperature approaches the set temperature, the temperature controlCPUUtilizing low-powerPWMMethod of heating, sampled temperature valuePIDCompute and analyze the bestPWMMaintain the duty cycle control to ensure the temperature is strictly within the preset temperature error range.

Measurement of Intermediate Loss

The test voltage is simultaneously applied to the internal standard capacitor of the instrument and the pressurized pole of the oil cup, with the measuring circuit processing these two signals.PGAOnce in control, synchronize signals across the two channels.ADSampling, transmitting digital signalsDSP(Digital Signal Processor)DSPFilter it.FFTThe calculation results after the operation are as follows:tgδ、C x  、Parameter ε, send to the main controllerCPU。

Volume Resistivity Measurement

DC high-voltage test voltage is applied to the oil cup's pressurized electrode, passing through the test circuit to generate a faint current signal. This faint current signal is then amplified by the measuring circuit and sent in.ADSampling, transmitting digital signalsDSP(Digital Signal Processor)DSPProcess the signal and calculateRxParameters such as ρ, etc., sent to the master controlCPU。

No Chinese content provided.

Trial sourceAC  tgδ: Tangent of the loss angle of oil sample medium

Cx   ：Electrical capacitance of oil sample bottles.

εr  ：The relative dielectric constant is calculated based on the capacitance value.

Trial sourceDC     Rx  ：Insulation resistance of oil samples

ρ  ：The volume resistivity of the oil sample is obtained by conversion from the insulation resistance.