Pressure sensitive resistance selection analysis example: the application types of varistor, use in different occasions, varistor applications, role in the varistor voltage / current stress is not the same, so the requirements of varistor is not the same, pay attention to distinguish the difference, for correctly using is very important.
According to different purposes, it can be divided into two categories: 1.
Although the pressure sensitive resistance can absorb a great surge of electrical energy, but can not withstand the current level of more than Ma, in the use of overvoltage protection must be taken into account. The selection of the pressure sensitive resistance, the general choice of nominal voltage sensitive voltage V1mA and the flow capacity of two parameters.
1, the so-called pressure sensitive voltage, that is, the breakdown voltage or threshold voltage. Refers to the voltage value in the specified current, in most cases with 1mA DC current into the voltage value of the voltage value of the voltage, the voltage range of its products can range from 10-9000V. According to the specific needs of the correct choice. General V1mA=1.5Vp=2.2VAC, type, Vp for the peak voltage of the circuit. VAC effective value for rated AC voltage. The choice of voltage value of ZnO is very important, it is related to the protection effect and service life. If the rated supply voltage of an electric appliance is 220V, then the voltage value of the voltage sensitive resistor is V1mA=1.5Vp=1.5 * 1.414 * V1mA=2.2VAC=2.2, 220V=476V * 220V=484V, so the breakdown voltage of the voltage sensitive resistor can be between 470-480V.
2, the so-called through flow capacity, i.e., the maximum peak current pulse is ambient temperature of 25 DEG C under, for the provisions of impulse current waveform and the provisions of the impact of current times, varistor voltage change does not exceed + / - 10% of the maximum pulse current value. In order to prolong the service life of the device, the amplitude of surge current absorbed by ZnO is less than the maximum flow rate of the product given in the manual. However, from the protection of the effect of starting, the demand for the flow of a large number of good. In many cases, the actual traffic is difficult to accurately calculate the flow, then the use of 2-20KA products. Such as hand products through flow can not meet the use requirements, using only a few individual varistor parallel, parallel varistor unchanged through the flow for each odd varistor and numerical. It is required that the voltage sensitive resistance of parallel connection is the same as that of the same, otherwise it is easy to cause the shunt is not uniform and the damage is caused by the pressure.
In this small series for the vast number of friends introduced the varistor selection analysis of knowledge, if you need to select the varistor can be used as reference data, but the above Xiaobian introduce also just in theory, in the actual application, or to according to the actual situation to choose suitable varistor, if pressure sensitive resistor selection of inappropriate words, resulting in an accident or cause the fault occurrence of May, so we in the choice of varistor or to pay attention to choose the quality assurance products. As Shenzhen tage Technology Co. Ltd. small, hope this small series will be introduced to the vast number of friends help. At the same time, also hope that the friends of tage Technology Co. Ltd. has support and encouragement, thank you!