How to use the multimeter to measure resistance with 4-wire method and 6-wire method
There are more accurate methods for measuring resistance than the two-wire method, namely the 4-wire method and the 6-wire method. The two-wire method is to connect the continuous measured resistance wire to the digital multimeter, and the resistance of the connecting wire is also included in the measured resistance value, and they cannot be separated. The 4-wire method or kelvin method is used to measure resistance. A pair of wires is connected to the current source, and the other pair of wires (sensing wires) is used to introduce the voltage drop on the measured resistance into a digital multimeter for measurement. Since the current flowing through the sensing line is very small, the measured resistance value is closer to the real value. Especially when measuring low-value resistance, the resistance value of the connecting wire can be of the same order as the measured resistance value, and the error is very large.
If the low-value resistance is measured by the 4-wire method, the lead wire resistance can be excluded, so that the measurement accuracy is better. When measuring a large-value resistance, there will be a bypass current no matter what, and taking protective measures for the measured resistance can solve the error caused by the bypass current. However, protective measures are usually used when measuring large value resistances with two wires. . A digital multimeter can also be used for 6-wire resistance measurement, and 4-wire method plus two protection wires. The 6-wire method is usually used to measure a single resistor in a resistor network. All other resistors connected to the measured resistor in the network are connected to the protection terminal. This effectively isolates the resistance being measured from it. The terminal voltage at each end of the measured resistance and the voltage on the protection end are generated by separate power sources, which also eliminates the error caused by the sensed line resistance. Typically, high-resolution instruments have 6-wire measurement capabilities. The 4-wire method is generally used for 4-5-digit digital multimeters. These measurements are described in footnotes. If there is no footnote, only the two-wire method can be used to measure resistance.
