1、 Classification of current for DC resistance testers
The measurement current of a DC resistance tester mainly includes the following two types:
1. Small current: usually 10 milliamperes, used to measure high resistance and low power resistance.
2. High current: generally 1 ampere, 5 ampere, 10 ampere, etc., used to measure low resistance values and high-power resistance.
2、 Principles for selecting the current of a DC resistance tester
In practical applications, the selection of current should be determined based on the resistance value and power of the measured resistance. Generally speaking, the magnitude of the current is inversely proportional to the resistance and power of the measured resistance. That is to say, the smaller the resistance and the higher the power, the higher the current to be selected. On the contrary, the higher the resistance and the lower the power, the lower the current to be selected.
3、 Specific current selection plan
1. Low current
When the resistance value of the tested resistor is large and the power is low, a small current should be selected for testing. Generally speaking, when the resistance value of the measured resistance is above 100 ohms and the power is 0.25 watts or less, it is better to choose a small current of 10 milliamperes for testing.
2. High current
When the resistance value of the measured resistance is small and the power is high, a high current should be selected for testing. Generally speaking, when the resistance value of the measured resistance is less than 100 ohms and the power is above 0.25 watts, it is better to choose high currents such as 1 ampere, 5 ampere, or 10 ampere for testing.
It is worth noting that the selection of current also needs to consider the withstand capacity of the measured resistance. If the withstand current of the measured resistance is small, selecting a larger current for testing will directly damage the measured resistance. Therefore, while selecting the current, attention should also be paid to the withstand current range of the measured resistance.
4、 Summary
The standard for selecting the current of a DC resistance tester is based on the resistance value and power of the tested resistance, usually using two methods: low current and high current for testing. In practical applications, attention should also be paid to the withstand current range of the measured resistance to avoid damage to the measured resistance. Choosing the correct current can improve the accuracy and reliability of testing, and can also extend the lifespan of the tested resistor.