Some Tips for Measuring Resistance with a Digital Multimeter
When using a resistance file greater than 1MQ (such as 2M.Q, 2OMQ file) for measurement, the value displayed on the LCD screen will jump a few times first, and then gradually stabilize after a few seconds. The displayed value of the LCD screen will jump Phenomenon, it will become stable after a few seconds, which is a normal phenomenon, and you should wait for the indication value to stabilize before reading. If the measured resistance exceeds the maximum value of the selected range, the LCD will display the overflow symbol "1". In this case, you should change to a higher range for measurement. When there is no input (that is, the two test leads are open), the LCD will display the overflow symbol
"1", this is normal.
Some digital multimeters have a 200M~ high resistance file. the file
There is an inherent zero point error of 1Mfl, which is 10 digits for a 3-digit meter, and 100 digits for a 4-digit meter. When measuring high resistance, the initial value should be deducted from the reading to obtain the actual value. For example, use DT890A digital multimeter 200MK~ to test the resistance value of a metal film resistor is 101.0MΩ, subtract 10 characters from it, the actual resistance value should be 100.0MΩ. When measuring low resistance with 200Ω range, you should first short-circuit the two test leads and measure the resistance value of the two test lead leads. This value is the actual resistance value. For the range of 2kΩ-20MΩ, the lead resistance of the test lead is negligible, so no correction is required. When measuring resistance (especially low resistance), the test plug and socket must be in good contact, otherwise it will cause measurement errors or cause unstable readings. When measuring the online resistance, the influence of other components connected in parallel with it should be considered. Some new digital multimeters have added a low-power method to measure resistance, and its symbol is "LOWOHM. The open circuit voltage of this file is lower than 0.3v, and the parallel effect of the silicon tube on the circuit under test can be ignored. The low-power resistance file is suitable for testing online Resistance value. The open circuit voltage, full-scale test voltage and short-circuit current of each resistance file are different, and the value of the short-circuit current decreases with the increase of the range. When measuring the resistance, both hands should not touch the metal end of the test lead or the lead-out of components terminal, so as not to introduce human body resistance and affect the measurement results. It is strictly forbidden to measure the resistance when the circuit under test is charged, and it is not allowed to directly measure the internal resistance of the battery.
