压敏电阻的型号及选用方法

Varistor models and methods of selection

李荣武

SJ1152-82部颁标准中压敏电阻器的型号命名分为四部分，各部分的含义见表1。

SJ1152-82 ministerial standards in the pressure-sensitive resistor model name is divided into four parts, each part of the meaning of Table 1.

表1 压敏电阻器的型号命名及含义

Table 1 varistor model names and the meaning

第一部分用字母“M”表示主称为敏感电阻器。

第二部分用字母“Y”表示敏感电阻器为压敏电阻器。

第三部分用字母表示压敏电阻器的用途的特征。

第四部分用数字表示序号，有的在序号的后面还标有标称电压、通流容量或电阻体直径、电压误差、标称电压等。

例如：

MYL1-1（防雷用压敏电阻器）MY31-270/3（270V/3kA普通压敏电阻器）

M——敏感电阻器M——敏感电阻器

Y——压敏电阻器Y——压敏电阻器

L——防雷用31——序号

1-1——序号270——标称电压为270V

3——通流容量为3kA

压敏电阻是一种以氧化锌为主要成份的金属氧化物半导体非线性电阻元件；电阻对电压较敏感，当电压达到一定数值时，电阻迅速导通。由于压敏电阻具有良好的非线特性、通流量大、残压水平低、动作快和无续流等特点。被广泛应用于电子设备防雷。

主要参数：

1、残压：压敏电阻在通过规定波形的大电流时其两端出现的最高峰值电压。

2、通流容量：按规定时间间隔与次数在压敏电阻上施加规定波形电流后，压敏电阻参考电压的变化率仍在规定范围内所能通过的最大电流幅值。

3、泄漏电流：在参考电压的作用下，压敏电阻中流过的电流。

4、额定工作电压：允许长期连续施加在压敏电阻两端的工频电压的有效值。而压敏电阻在吸收暂态过电压能量后自身温度升高，在此电压下能正常冷却，不会发热损坏。

压敏电阻的不足：（1）寄生电容大压敏电阻具有较大的寄生电容，一般在几百至几千微微法的范围。在高频信号系统中会引起高频信号传输畸变，从而引起系统正常运行。

（2）泄漏电流的存在压敏电阻的泄漏电流指标既关系到被保护电子系统的正常运行，又关系到压敏电阻自身的老化和使用寿命。

压敏电阻的损坏形式：（1）当压敏电阻在抑制暂态过电压时能量超过其额定容量时，压敏电阻会因过热而损坏，主要表现为短路、开路。

MYL表示防雷型压敏电阻

MYE表示高负荷型压敏电阻,也有厂家用MYT表示通用型，MYL表示防雷型.

选用方法(一般情况）:

1、压敏电压值应大于实际电路的电压峰值，一般为：

U1mA =K1×/K2×K3× UC

U1mA ---- 压敏电压

UC ---- 电路直流工作电压（交流时为有效值）

K1 ---- 电源电压波动系数，一般取1.2

K2 ---- 压敏电压误差,一般取0.85

K3 ---- 老化系数,一般取0.9

交流状态下，应将有效值变为峰值，即扩大√2倍，实际应用中可参考此公式通过实验来确定压敏电压值。

2、通流量

实际应用中，压敏电阻器所吸收的浪涌电流应小于压敏电阻的最大峰值电流，以延长产品的使用寿命。

压敏电阻的检测。用指针式万用表的R×1k挡测量压敏电阻两引脚之间的正、反向绝缘电阻，均为无穷大，否则，说明漏电流大。若所测电阻很小，说明压敏电阻已损坏，不能使用。

Varistor is a zinc oxide as the main component of non-linear resistance metal oxide semiconductor components; resistance of the voltage sensitive, when the voltage reaches a certain value, the rapid turn-on resistance. As the varistor has a good non-linear characteristics of large-volume, low levels of residual pressure, fast action and continued flow and so on. Has been widely used in electronic equipment, lightning protection.

The main parameters:

1, residual pressure: pressure-sensitive resistance in the adoption of the provisions of the current wave when the peak occurred at both ends of the voltage.

2, flow capacity: the required time and in the number of varistors to impose requirements on current form, the varistor voltage reference rate of change is still within the framework of the provisions can be adopted by the current maximum amplitude.

3, leakage current: In reference to the role of voltage, resistance pressure-sensitive stream-off current.

4, rated voltage: to allow for long-term restrictions on the two ends of the varistor voltage frequency of RMS. The varistor in the absorption of over-voltage transient energy after their own temperature, the voltage in the normally cool, heat will not be damaged.

Varistor less than: (1) large parasitic capacitance varistors with higher parasitic capacitance, typically a few hundred to several thousand law slightly. High-frequency signals in the system will cause high-frequency signal transmission distortion, which led to the normal operation of the system.

(2) the existence of leakage current varistor leakage current targets were not only related to the protection of the normal operation of electronic systems, and related to the pressure-sensitive resistance and service life of its own aging.

Varistor damage in the form of: (1) When the varistor in the transient voltage suppression when energy than its rated capacity, the varistor will be overheating as a result of damage, mainly to short-circuit, open circuit. MYL said lightning-varistor

MYE said that the high-load varistor as well as manufacturers that use MYT size-fits-all, MYL that type of mine.

Selection methods (general):

1, voltage-sensitive value should be greater than the actual peak voltage of the circuit, in general:

U1mA = K1 × / K2 × K3 × UC

U1mA ---- voltage-sensitive

UC ---- circuit voltage direct current (exchange for RMS)

K1 ---- power supply voltage fluctuation coefficient, in general take 1.2 K2 ---- error voltage-sensitive, 0.85 general admission

K3 ---- aging factor, in general take 0.9

The exchange of state, should become effective value peak, that is, the expansion of √ 2 times the practical application of this formula can refer to the experiment to determine the value of the voltage-sensitive.

2, flow -

Practical applications, the varistor absorbed by the current surge should be less than the maximum varistor peak current in order to extend the service life of the product.

Pressure-sensitive detection of the resistance. Analog multimeter to use the R × 1k block measuring varistor between the two pin is, reverse the insulation resistance, are infinite, or that large leakage current. If the

measured resistance is very small, pressure-sensitive resistance that has been damaged and can not be used.