The volume resistance tester is a core tool in the field of high resistance measurement. Its working principle and system composition are based on high precision and anti-interference ability, providing reliable basis for the electrical performance evaluation of high resistance objects such as insulation materials and electronic components.
Working principle: Accurate application of synchronous voltage and current measurement and Ohm's law
The volume resistance tester is based on the extended principle of Ohm's law, and directly calculates the resistance value (Rx=V/I) by synchronously measuring the voltage (V) applied to both ends of the sample and the weak current (I) flowing through the sample. Unlike the traditional high resistance meter's fixed voltage and current only "non-linear scale" mode, modern instruments use synchronous measurement technology. Even if the voltage or current fluctuates, the division operation can still be completed in real time through the internal integrated circuit, ensuring the linear accuracy of the resistance value display. Its current detection lower limit can reach the flying safety level (10 ⁻¹⁵ A), coupled with a high-voltage source (adjustable from 10V-10kV), it can cover a wide measurement range from 10 ⁶Ω to 10 ¹⁸, with theoretical errors approaching zero and actual errors controlled within a few thousandths to ten thousandths.
System composition: three modules cooperate to achieve high-precision measurement
Core measurement module: Integrated high voltage source, micro current amplifier (resolution up to 10 ⁻¹⁵ A), and digital processing unit. The high voltage source provides stable test voltage, the micro current amplifier converts nanoampere level current into measurable voltage signal, and the digital processing unit achieves real-time calculation and display of resistance value through A/D conversion.
Electrode system: Adopting a three electrode system (main electrode, protective electrode, counter electrode) or a two electrode system. The three electrode system eliminates edge leakage current interference by protecting the electrodes, ensuring that the current only flows through the interior of the sample and is suitable for volume resistance testing; The two electrode system is used for surface resistance measurement, separating the surface and volume conductive paths through a double ring electrode.
Protection unit: includes a double-layer electromagnetic shielding box, independent grounding device, and humidity monitoring module, which can reduce environmental interference to below 0.1pA. At the same time, the instrument supports constant temperature control (such as 23 ± 2 ℃) to avoid the influence of temperature and humidity fluctuations on the measurement results.