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The resistance value measured by the multimeter with braking resistor is close to the nominal value
Apr 11, 2018

The resistance value measured by the multimeter with braking resistor is close to the nominal valu

Also note that the human hands do not touch the two ends of the resistor or contact the metal part of the pen. Otherwise it will cause a test error. The resistance value measured by the multimeter is close to the nominal value. It can be assumed that basically quality is good if it is too much or not at all is bad.


Testing


1, appearance inspection


For the fixed resistance, first check the mark clearly to protect the paint from being burned, no burns, no cracks, no corrosion, no contact between the resistor body and the pin. For the potentiometer also should check the shaft is flexible and appropriate feel comfortable. Switch to check whether the switch is normal.


2, multimeter detection


1 fixed resistance detection


Measure the resistance with the multimeter's electrical blocker. Select the multimeter's different multipliers for measuring resistances with different values. For the pointer multimeter, the number of resistances is non-linear, and the larger the resistance number is, the denser the number is. Therefore, selecting the proper range should make the needle deflection angle larger to indicate that the 1/3 2/3 full-scale reading is more accurate. If the measured resistance value exceeds the error range of the resistor, the resistance value is infinite, the resistance value is 0 or the resistance value is unstable, indicating that the resistor is bad. Take care not to touch the two pins of the resistor during measurement. This will make the resistance presented by the hand in parallel with the measured resistance affect the measurement accuracy. In addition, it is not possible to use a multimeter to block the resistance of the resistor of the resistor in the detection circuit. The on-line test should first disconnect the power and disconnect the resistor from the circuit before making the measurement.


2 Detection of fuse resistance and sense resistance


The general resistance of the fuse resistor is only a few to several tens of Euro. If the measured resistance is infinite, the fuse is blown. It is also possible to measure the resistance of the fuses online and measure their voltage across the ground. If one end is the supply voltage, the one end voltage is 0 volts. The fuse resistance is blown. There are many types of sensitive resistors. Thermistors are divided into positive temperature coefficient and negative temperature coefficient thermistors. For the positive temperature PTC thermistor, the general resistance is not large at room temperature. In the measurement, use a hot soldering iron near the resistor. The resistance value should be increased significantly. This indicates that the resistor is normal, if no change, the component is damaged. The resistance is the opposite.


3 Variable resistance and potentiometer detection


First of all, it is measured whether the resistance value between two fixed ends is infinity or zero-Europe, or the deviation from the nominal value is larger than the allowable range of error. All indicate that the resistance of the resistor is normal, and then one meter is connected to the wiper of the potentiometer. The other pen holder is connected to the potentiometer Adjustable resistance of any fixed end Slowly rotate the mandrel Observe that the hands change steadily. When turning from one end to the other, the resistance value changes from zero to nominal or vice versa and there is no jump or Jitter and other phenomena indicate that the potentiometer normally jumps or flickers during rotation, indicating that the sliding point is a poor contact with the resistor.


3, using a bridge to measure resistance


If it is required to accurately measure the resistance of the resistor, it can be tested digitally through the bridge. Insert the resistor into the measuring terminal of the bridge element and select the proper range to read out the resistance of the resistor from the display. For example, when a resistor is used to build a resistor or a fixed resistor is processed to obtain a more accurate resistance value, the bridge must be used to measure the resistance of the self-made resistor. Application of different occasions to apply varistors The purpose of the varistor is to apply different voltage/current stress to the varistors and thus the requirements for the varistors are not the same. It is very important to distinguish these differences for proper use. Depending on the purpose of use, varistors can be divided into two major categories of varistors used for the protection of varistor circuits.