Temperature Effect on Safety Capacitance

Unconsciously summer came and the weather became hotter and hotter. Many friends in the electronics industry may not know that temperature has an effect on capacitors. Under normal circumstances, when manufacturers choose capacitors, they generally consider only the capacitance and withstand voltage of the capacitors, and ignore the effect of temperature on the capacitors, allowing the capacitors to operate at unsuitable temperatures. So here I edit to tell everyone about the effect of temperature on capacitors.

1. The impact of safety capacitor life.

The life of the capacitor is shortened as the temperature increases. Under normal circumstances, the capacitor life is reduced by half every 10°C. Any capacitor has its operating temperature range. Take a capacitor with 30,000 hours of life and quality as an example, it can work at 20-120 degrees, but it can work more than 30,000 hours between 20-40 degrees, but if it works At his extreme temperature (120 degrees), his working life may be reduced to less than 3,000. Therefore, when selecting a capacitor, it is necessary to select a high temperature-resistant, good-quality safety capacitor, and to ventilate the heat when designing the circuit.

2. The impact of the safety capacity of the capacitor

The capacity of the capacitor changes with temperature, which we call the temperature coefficient of the capacitor. It varies from +22% to -82%. When the temperature is too high, the compensation capacity of the capacitor decreases, and it will resonate with harmonics of a certain frequency in the power grid, causing damage to the system. Therefore, when designing a precision capacitor timing circuit and an oscillation circuit whose frequency is determined by the capacitance, the influence of temperature on the capacitance of the safety capacitor must be taken into consideration. Otherwise, the design of the capacitor timing circuit will be inaccurate timing, causing damage to the system.

3. The effect of loss of safety capacitor

The value of the loss of the capacitor due to temperature rise is called the loss tangent of the capacitor. In general, the tangent increases as the temperature increases. If a safety capacitor operates at a temperature of 20-30 degrees, the tangential value is 0.0010, and when it operates at a temperature of 100 degrees, the tangent value may be 0.0020. This shows that the loss of the temperature to the safety capacitor is How big is it.