Kingtronics Blog

The use principle of Varistor is that after it is connected to the protected equipment, it cannot affect the normal operation of the equipment, and can effectively implement instantaneous overvoltage protection for the equipment. Therefore, in addition to the technical parameters of Varistor, the following issues should be considered in the actual selection:

(1) Selection of voltage sensitivity
Considering the deviation between the actual Varistor voltage and the nominal voltage (1.1~1.2 times of the nominal voltage should be considered), the possible fluctuation range of the power supply voltage in the AC circuit (1.4~1.5 times of the rated voltage should be considered), and the relationship between the peak value of the AC voltage and the effective value (1.4 times should be considered), the Varistor with a voltage sensitive of 2.2~2.5 times of the rated voltage should be selected. In DC circuits, Varistor with a voltage sensitive of 1.8~2 times the rated value of DC voltage are often selected.

⑵ Selection of flow capacity
In principle, the selection should be based on the maximum transient surge current that may be experienced, but achieving this is difficult. In practice, the selection of Varistor is based on the use occasion or the test grade specified in the product test standard.

According to the former, 1kA (8/20 μ S current wave) can be used for the protection of silicon controlled rectifier; 3kA is used for surge absorption in electrical equipment; 5kA is used for overvoltage absorption of lightning strikes and electronic equipment; 10kA is used for protection against lightning strikes. According to the latter, the commonly used composite wave (1.2/50 generated when the generator is open circuit output) μ Voltage wave of s; 8/20 generated during short-circuit output μ Current wave of s; The internal resistance of the generator is 2 Ω to assess the equipment's ability to withstand lightning surge interference online. During the 4kV test, the maximum current absorbed by the protector can reach 2kA; For the 6kV test, the maximum absorbed current is 3kA. However, in actual selection, the flow capacity of the selected Varistor should also be appropriately increased. Because Varistor with large current passing capacity should have relatively small residual voltage drop when absorbing surge current of the same size; At the same time, there is also a large protection margin for the selected Varistor.

⑶ Inherent parasitic capacitance
Varistor has an inherent capacitance problem. Its value ranges from hundreds to thousands of pF according to the difference of external dimensions and nominal voltage. The inherent capacitance of Varistor determines that it is not suitable for use in high-frequency occasions, or it will affect the normal operation of the system; Suitable for use in power frequency systems, such as for protection of power incoming lines, protection of thyristor rectifiers, etc.

The instantaneous power of Varistor is relatively large, but the average continuous power is very small, so it cannot work in the conduction state for a long time.https://www.kingtronics.com/Metal-Oxide-Varistor/XKT-Metal-Oxide-Varistor.html 

Kingtronics Kt 05D to 20D Metal Oxide Varistor Features
Operating Temperature Range: -40℃~+105℃
Body Diameters Range From 5D to 20D
Wide Operating Voltage from 18V to 1800V
Full compliance with RoHS and REACH

Kingtronics Kt 05D to 20D Metal Oxide Varistor Applications
Industrial equipment
Home appliance
Industrial equipment
Lighting products
Telecommunication or telephone system

Christmas/New Year Holidays are around the corner, various customers have released their orders to us for a better L/T.

No doubt L/T near Xmas/New Year will be extended, it’s always wise to make schedule earlier.

Welcome send your order plan to us in Nov., we can give you a better lead time!!

Here is the information about our best sellers.

Kingtronics-ElectronicsAsia-2019-Capacitors.pdf

Hello my dear friend,
 
Wish you enjoy a nice weekend. :-)
 
This time our starring role is Trimming potentiometer, which is a kind of variable resistor and called trimmer and preset. It's meant to be set correctly when installed in some device, and never seen or adjusted by the device's user. It can be used in many fields such as inspection machine, remote control, amplifier, controler, smoke detector...
 
Are you manufacturer in these fields or distributor for electronic components? Do you have demand for trimming potentiometer? Could you pls send me your request and I will reply you soon.
 
We Kingtronics is one of the oldest factories for trimming potentiometers in China. Our Trimming Potentiometer is ISO &SGS certified. With more than 20 years' development, our trimmer sell to many famous distributors, and can cross to many famous brands like Bourns, Murata and Vishay. We can offer you very good price and 3-4 weeks delivery. 
 
Trimming potentiometer: 3006 3386 3266 3296 3329 C3305 065
 
Could you pls help us promote to your clients or friends who use or buy them? Sending me your inquiry and let me quote best price for you, ok?
 
Look forward to your response and pls email to info@kingtronics.com