2. Heat-generation characteristics of capacitors In order to measure the heat-generation characteristics of a capacitor, the capacitor temperature must be measured in the condition with heat dissipation from the surface due to convection and radiation and heat dissipation due to heat transfer via the jig minimized.
Capacitors have resistance in their electrodes and dielectrics. This resistance generates heat when AC current like ripple current – a periodic non-sinusoidal waveform derived from an AC power source – passes through.
Cooling a capacitor helps to enhance its performance as well as its reliability. Cooling will extend its life; taking away more heat from the capacitor can also give it more power-carrying ability. Murray Slovick dig into more details of methods and principles how to cool capacitors in his article published by TTI Market Eye.
Every 10° C increase in internal temperature halves the component lifetime. The structure and materials used in the capacitor make heat dissipation more difficult. To operate properly, the case must be electrically isolated from the core where heat is generated. The voltage breakdown of the insulation materials is often in excess of 350 volts DC.
In most cases, the primary thermal conduction path (the path of least resistance) is from the closed or flat end of the capacitor. Some heat also passes through the terminal end. Capacitor heat loads are small: typically 5 to 10 Watts in a 3 inch diameter capacitor.
1. Capacitor heat generation As electronic devices become smaller and lighter in weight, the component mounting density increases, with the result that heat dissipation performance decreases, causing the device temperature to rise easily.