Shantou Xinyin Electronic Technology Co., Ltd

1. Principles for selecting withstand voltage values

The withstand voltage value is the maximum voltage upper limit that a capacitor can operate stably for a long time. When selecting, the core principle of leaving sufficient safety margin should be followed, and the following points can be referred to for details:

• Match the actual voltage of the circuit

  Firstly, clarify the peak voltage in the circuit, and the selected capacitor's withstand voltage must be higher than the maximum peak voltage of the circuit, rather than just matching the rated operating voltage. For example, in an AC circuit, the peak voltage may be higher than the effective value, and additional margin needs to be reserved.

• Reserve safety margin

  Considering factors such as voltage fluctuations and temperature changes, it is recommended to reserve a safety margin of 20% to 50% on top of the peak voltage of the circuit. Especially in high voltage and high current scenarios such as industrial equipment and new energy, the margin needs to be appropriately increased to avoid capacitor breakdown due to instantaneous overvoltage.

• Adjust according to the application scenario

  Low voltage scenarios such as consumer electronics: can be selected according to conventional margins;

  Scenarios with voltage spikes such as motor start-up and inverter circuits require further improvement in voltage withstand level;

  Usage in high temperature environment: The withstand voltage capability of capacitors will decrease, and it is necessary to increase the selected withstand voltage value in a targeted manner.

2. Precautions for use

• Strictly prohibit the use of overvoltage resistance

  If the actual voltage of the circuit is close to or exceeds the withstand voltage value of the capacitor for a long time, it may cause breakdown of the capacitor dielectric, resulting in leakage, bulging, or even explosion, and may also damage other components in the circuit.

• Distinguish AC/DC withstand voltage

  Some capacitors will be labeled with alternating current withstand voltage (AC) and direct current withstand voltage (DC), and the two cannot be mixed. AC capacitors can be used in DC circuits (provided that the DC voltage does not exceed the AC withstand voltage value), but DC capacitors cannot be directly used in AC circuits.

• Pay attention to the influence of temperature on voltage resistance

  The withstand voltage value of capacitors will decrease with increasing temperature. In high-temperature environments, it is necessary to avoid capacitors being in a fully loaded withstand voltage state for a long time. If necessary, heat dissipation design or upgrading the withstand voltage level can be used to ensure stability.

• Balance between voltage resistance and capacity

  Among capacitors of the same type, the higher the withstand voltage value, the larger the volume, and the capacity may be limited. When choosing, it is necessary to take into account the requirements for voltage resistance, circuit installation space, and capacity, and avoid blindly pursuing high voltage resistance, which may lead to cost and volume waste.