Parameters to pay attention to when purchasing film capacitors

1. Rated voltage

The rated voltage refers to the voltage value applied across the capacitor that the film capacitor can operate normally, stably, and reliably for a certain period of time in the circuit. The rated voltage is not only related to the dielectric structure of the capacitor, but also related to the environment in which the capacitor is placed. When the frequency and temperature rise, the rated voltage will drop. Therefore, the rated voltage of the capacitor should be noted when purchasing the film capacitor. If the temperature rises very badly, the voltage applied across the film capacitor should be reduced accordingly. However, it is good to choose a capacitor with a rated voltage slightly higher than the actual demand when selecting a film capacitor to ensure normal, stable and reliable use of the capacitor.

2. Capacity

Capacitance is very important. It is related to whether the capacitor can meet the needs of the circuit. It is to ensure that the circuit can achieve the goal determined by the design. The capacitance of a capacitor refers to the storage capacity of a capacitor for a charge. When purchasing, the capacitance required by the circuit must be selected. It can be chosen to be larger, but not too large.

3. Temperature coefficient

The temperature coefficient refers to the ambient temperature range in which the capacitor can work stably in the circuit. Generally, the temperature coefficient of the film capacitor ranges from -65 °C to +250 °C, and the capacitor with a suitable temperature coefficient can be selected according to the temperature of the working environment.

4. Loss

Loss refers to the energy lost by a capacitor in a circuit per unit of time due to heat dissipation. The heat dissipated by the capacitor loss causes the temperature of the capacitor itself to rise, and a portion of the heat is dissipated to the surrounding environment. When purchasing, try to choose a thin film capacitor with a small loss, so that the capacitor stores more charge into the capacitor instead of converting the electric energy into heat to do useless work.