Varistor is an all-too-familiar word for technical engineers. So for the small white project, it should be a time to deeply understand and explore the function and performance of the varistor. Xiaobian here will not be around the topic, here? Kester technology Xiaobian brings you: the basic performance of varistor in circuit function and protection. The following is the data analysis prepared by Xiaobian for you:
Varistor in circuit function:
Varistors are mainly used for transient overvoltage protection, but their voltammetry characteristics, similar to those of semiconductor regulators, also give them a variety of circuit component functions, such as:
(1) DC high voltage small current voltage regulator, its stable voltage can be up to several thousand volts above, which is silicon voltage regulator can not reach. (Recommended reading: How to test varistor? Method of measuring varistor)
(2) Voltage fluctuation detection element.
(3) DC battery shift element.
(4) voltage balancing element.
(5) Fluorescent starting element
Basic properties of protection varistors:
(1) Protection characteristics, when the impact of the impact source (or impact current Isp=Usp/Zs) does not exceed the specified value, the limited voltage of the varistor is not allowed to exceed the impact withstand voltage (Urp) that the protected object can withstand. (Recommended reading: Protection principle of varistor (MLV/MOV), TVS tube and varistor application)
(2) shock resistance characteristics, that is, the varistor itself should be able to withstand the specified impact current, impact energy, and the average power when multiple shocks occur one after another.
(3) There are two life characteristics, one is the continuous working voltage life, that is, the varistor should be able to reliably work for the specified time (hours) under the specified ambient temperature and system voltage conditions. The second is the impact life, that is, the number of times that it can reliably withstand the specified impact.
(4) After the varistor is involved in the system, in addition to playing the protective role of the "safety valve", it will bring some additional effects, which is the so-called "secondary effect", which should not reduce the normal working performance of the system. At this time, there are three main factors to consider, one is the capacitance of the varistor itself (tens to tens of thousands of PF), the second is the leakage current under the system voltage, and the third is the impact of the nonlinear current of the varistor through the coupling of the source impedance on other circuits.