Working principle of the variable frequency anti-interference dielectric loss tester:
The instrument's measurement circuit includes a standard circuit and a test circuit, as shown in Figure 3. The standard circuit consists of a built-in high-stability standard capacitor and a sampling circuit, while the test circuit consists of the test object and a sampling circuit. Using a microcontroller with computer-based digital real-time sampling, it processes tens of thousands of sampled data points and performs vector operations to measure the amplitude and phase relationship of the current in the standard circuit and the test circuit respectively. From this, it calculates the capacitance value (Cx) and the dielectric loss tangent (tgδ) of the test object, ensuring reliable measurement results. When there is interference on site, the phase-shifting and polarity-reversal methods are first used to reduce the impact of interference, then the current Ix' measured in the test circuit is vectorially added to the separately measured interference current Id to obtain the true measurement current Ix, thereby yielding correct measurement results. Depending on the measurement object and requirements, various wiring configurations can be flexibly adopted. For example, when measuring non-grounded test objects (normal connection method), the "Lv" (E) point is grounded; while when measuring grounded test objects (reverse connection method), the "Hv" point is grounded.
