How does a varistor measure good or bad? Pressure sensitive resistance test method! Today I Shenzhen tage electronic technology small test method in micro us all about it, a good measure of varistor!
The use of varistors is usually parallel to the circuit. When the voltage changes sharply at both ends, the varistors may be short circuited, so that the current fuse will be blown off, which will play a protective role to some extent. The function of the varistor is to protect and stabilize the power of the power supply when the power is high.
The characteristic of varistor is that the resistance decreases with the increase of voltage, and it can be reduced from Mega to millieu level. The amplitude is very large, and the voltage sensitive characteristic is obvious. When the voltage is at a low value, the varistor is in the leakage current working area. At this time, the resistance value of the varistor is very large and the leakage current is very small, so it can be ignored. When the voltage rises into the nonlinear area, the current changes in a considerable range, the voltage is basically unchanged, and the effect of the voltage restriction is obvious. The voltage continues to rise, exceeding the load of the varistor, and the overcurrent load is too high to cause the varistor to be destroyed or cracked.
The measurement of varistor is damaged, with a multimeter to the 10K file, one connected resistor, the multimeter on the normal should show marked resistance of varistor, if beyond this value very much, that have damaged the varistor.
Special attention: it is necessary to know the voltage of the varistor to measure the varistor.