In the measurement of the varistor, first we must know the varistor voltage value, with an appropriate voltage source in series with a resistor voltage applied to the protection of the varistor varistor, voltage measurement value, whether in nominal value, and if it is, we can think the element is good. If there is a large difference between the nominal value and the nominal value, the voltage dependent resistance is a problem.
Varistor is a resistance, we just use ordinary multimeter, is unable to read the number of display is infinite.
The pressure sensitive resistance is a kind of semiconductor device with Zinc Oxide as the main raw material. Is a kind of nonlinear sensitive element. Only when the voltage is applied to the sensitive protection. Specific principles, two floor, said very well.
The measurement of the pressure sensitive resistance:
1 can choose the professional testing equipment of the pressure sensitive resistance.
2 can use the oscilloscope. Voltage test: when testing with an oscilloscope, the input current is set to 1MADC. to test its voltage to see if the voltage is consistent with the nominal voltage, if the voltage is low, it is said that the pressure sensitive resistance to damage. The pressure sensitive resistance has been short circuit, such as the occurrence of high voltage, or there is no nonlinearity, there is no curve, it shows that the pressure sensitive resistance has been open. Leakage current: when the test leakage current, you can check the nominal voltage value of the pressure sensitive resistance, will be transferred to the scope of the oscilloscope test voltage to the corresponding voltage value. Such as the current testing more than 100 microamps, the varistor has a problem, because the varistor in the factory test, leakage current control is very small, generally not more than 30 microamps. We can only do ordinary two, if you want to test other parameters, the oscilloscope can not be tested, and that requires a more professional equipment.
3 can be used to test with a million meters, such as the resistance value can be measured, basically can determine the resistance is a problem, do not apply.
Such as the use of substandard, poor quality of the pressure sensitive resistance, may occur in the explosion of pressure sensitive resistance components. Or affect the use of other components.
So when the varistor is broken, the varistor temporarily did not find the corresponding, can remove it, temporarily not used, as long as the voltage stability condition, a short period of time will not affect the use of your appliances. Because it is usually connected in parallel connection mode in the circuit. If the pressure sensitive resistor is damaged, don‘t replace it with common resistance, because it has no effect. The common resistance and the pressure sensitive resistance are two distinct components, which can not be replaced.
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