How to choose a varistor is an issue that many individuals will face. Under typical circumstances, in order to ensure the normal operation of the line and prevent damage to the varistor while protecting the line, the voltage value of the varistor should be selected within a predetermined range.
Typically, the minimum value of the varistor voltage in the protection circuit should satisfy the requirements of formula (1). In addition, the maximum value of the varistor voltage must match the requirements of formula (2) based on the protective circuit’s voltage withstand rating:
V1 ≈ 2. 2Vac or V1 Equals 2. 0Vdc (1) (1)
V1 ≤0.9Vz/ Kp (2)
V1-represents the varistor voltage value under 1mA DC current in the formula;
Vac-indicates the effective AC voltage value;
Vp-p is the peak-to-peak value of the AC voltage;
Vdc-Indicates the value of the DC voltage.
Vz-reresents the impulse insulation voltage withstand value of the protected equipment (or components) in the formula;
Kp-limiting voltage ratio, is a material-specific constant.
For instance, if the AC voltage of an electronic ballast is 220Vac, the minimum voltage value of the varistor should be V1 = 115 2 220V = 467 V. In accordance with IEC regulations, the protection level of electronic equipment is D-level protection, and its insulation withstand voltage value is typically specified as 115kV.
In fact, for specific electronic ballast products, if the pulse withstand voltage of the rectifier circuit is 1000V 1200V, and the ordinary varistor with a current capacity of 0 10 KA, and if the Kp value is 117 118, then, through calculation, the pressure The maximum varistor value of the varistor should be V1 019Vz/ K0191200/ 117643 V. Consequently, for electronic bal
Typically, varistors of type MYG3/ 150 (varistor voltage: 250 V) are utilized for electronic ballasts with a power supply voltage of 120Vac. Under the condition that the circuit design has been decided, it is possible to determine the protection level of the actual circuit by a large number of tests and select a more suitable varistor.
Next, how to choose MOV varistors, I believe everyone has a clear direction, and I hope this post may be of use. Mornsun is a global power supply solution provider integrating research and development, production, and sales with strong independent research and development and intellectual property rights advantages. We are committed to helping our customers improve their productivity and energy efficiency while reducing their environmental impact.
