The DC resistance tester instrument uses independent current output terminals
The DC resistance tester (often referred to as "direct resistance meter" or "micro-ohmmeter") is a core testing device in the power system specifically used for high-precision measurement of low resistance values.
Its core function is to measure the DC resistance of transformer windings, motor windings, cable conductors, and various switch contacts. Through precise resistance data, it judges the integrity of internal conductors, welding quality, and contact condition. It is an indispensable step in power equipment handover, overhaul, and preventive tests.
The following is a detailed introduction to the core principles, functions, and technical characteristics of such instruments:
⚡ Core Working Principle
Ohm's Law and Constant Current Source Technology: The instrument is based on Ohm's law (R=V/I). It applies a known and extremely stable DC test current (constant current source) to the measured object through internal circuits, while measuring the voltage drop across it with high precision, thereby calculating the resistance value.
Four-wire (Kelvin) measurement method: This is the key to achieving high-precision measurement. The instrument uses independent current output terminals (C1, C2) and voltage sampling terminals (P1, P2). This method completely eliminates the interference of test lead resistance and contact resistance on measurement results, ensuring accurate and reliable measurement even at micro-ohm (μΩ) level low resistance values.
