Several things you should know about high voltage resistor selection

Several things to note when selecting high-voltage resistors:
1. Why should we choose high-level epoxy encapsulated high-voltage resistors?
High-voltage resistors are used in power systems such as resistive transformers, and often require secondary potting. The surface of the resistor package must be smooth and must match the secondary potting material, otherwise tiny gaps may form between the surface of the resistor and the potting material. These tiny gaps will form local discharges under high-voltage environments, thereby carbonizing the packaging material. High-level epoxy resin encapsulation of high-voltage resistors is significantly better than traditional silicone resin encapsulation, which can avoid the local discharge phenomenon caused by secondary encapsulation and enhance the reliability and stability of the high-voltage system. Before potting, we recommend cleaning the surface of the high-voltage resistor, and applying a surfactant is conducive to a more perfect combination of the potting material and the resistor surface.
2. What kind of high-voltage resistor accuracy should be selected?
In the design process of resistive voltage transformers, a thick film high-voltage resistor and a fine-tuning potentiometer are generally used to complete the voltage division. The accuracy of the voltage division ratio can be adjusted by adjusting the fine-tuning potentiometer. This design can use high-voltage resistors with an accuracy of 1%, 2% or 5%. At present, the highest level of fine-tuning potentiometers are foil technology fine-tuning potentiometers, which have low temperature coefficients and good long-term stability. When two resistors are used to complete voltage division, it is necessary to select appropriate absolute accuracy and matching accuracy according to the requirements of voltage division ratio accuracy. Matching accuracy is more important.
3. How to choose a high-voltage resistor with low temperature drift?
In the application of voltage division, the ideal situation is that the temperature drift of the two resistors is consistent, that is, when the temperature changes, the resistance value of the resistor can change in the same direction, so that the voltage division ratio remains unchanged. Such a voltage-dividing resistor is called a voltage-dividing resistor with good tracking temperature drift. Generally, good tracking temperature drift can only be achieved after matching. Another method is to select two resistors with very low absolute temperature drift for voltage division, but the price of resistors with very low absolute temperature drift is usually very expensive.
4. Low voltage coefficient is the main parameter of precision high-voltage resistors
The mainstream high-voltage resistors are all thick film processes. The resistance of thick film process resistors will change in a high-voltage environment. This is because the thick film resistor is a mixture of conductive and non-conductive materials. In a high-voltage environment, the non-conductive medium is activated to form a parallel resistor, so that the resistance value of the resistor changes in a small direction as the voltage increases. The low voltage coefficient is determined by the resistor's paste level and manufacturing process.
5. Long-term stability is very important
High precision without stability is meaningless, because the resistance value of the resistor will change during storage or load, and this change is irreversible. These changes should be taken into account when selecting resistors to ensure that the changes are within the allowable range of measurement accuracy. Kaibu Electronics' high-voltage resistors are all tested for high voltage before leaving the factory. This test helps to stabilize the resistance value of the resistor.
6. The reliability of the resistor is related to the reliability of the entire system
The design life of the equipment puts forward requirements for the reliability of the resistor. In the high-voltage switch system, the resistor is not allowed to fail, so a high-voltage resistor with reliability indicators must be selected and necessary derating must be performed. Kaibu Electronics' high-voltage resistors have more than 20 years of experience in related applications of high-voltage switch systems, and the failure rate exceeds the military standard requirements.