Protective circuit design.Different test standards correspond to different protection schemes, and the protective circuit has several protection principles:

1. Safety principle: avoid equipment damage or injury or personal safety due to device action;

2. Reliability principle: can meet customer's test standard requirements;

3. Usability principle: it cannot affect the normal work of customer equipment;

4. Economic principle: select the most cost-effective devices to meet customers' requirements;

5. The principle of grading protection: determine whether or not the classification protection is based on the actual application environment.