Selection Of Surge Backup Protector For This Project

GB51348, page 163, 11.9.11 stipulates: Overcurrent protection devices should be installed on the surge protector installation line, and the overcurrent protection devices should have the following capabilities: 1. Disconnect the expected short-circuit current of the SPD installation line; 2. Withstand the surge current passing through the SPD without disconnection; 3. Disconnect the power frequency current that the SPD built-in thermal protection cannot disconnect.

The national standard clearly stipulates that surge protectors need to be equipped with dedicated backup protectors, which is based on safety considerations. Backup protectors have been used in China for 10 years, with mature technology, and have been widely used in various industries. As a bodyguard for surge protectors, it is different from fuses and circuit breakers in the following ways: 1. It can pass direct lightning strikes up to 25KA; 2. It can disconnect short-circuit currents up to 100KA; 3. It can disconnect small short-circuit currents of 3A to prevent surge protectors from catching fire.

This project uses a composite surge protector and a surge-specific backup protector, taking into account the flour mill's safety requirements and national standards: good surge quality, long life, no aftercurrent, no leakage current, and no fire; and is equipped with a special backup protector that complies with relevant national standards.