What are the protections for power equipment and line short-circuit faults?

Power equipment and lines in civil buildings shall be equipped with short-circuit faults and abnormal operation relay protection devices. Protection of power equipment and line short-circuit faults shall have primary protection and backup protection, and additional auxiliary protection may be added if necessary

1Main protection: It can meet the requirements of system stability and equipment safety, and can selectively remove the protected equipment and line fault protection at the fastest speed.

2 Backup protection: When the main protection or circuit breaker is rejected. Used to remove the protection of the fault. Backup protection can be divided into two ways: far backup and near backup.

a. Remote backup: When the main protection or circuit breaker refuses to move, the backup is realized by the protection of adjacent power equipment or lines.

b. Near backup: When the main protection is refused, the other protection of the power equipment or the line realizes the backup; when the circuit breaker refuses to move, the backup is realized by the breaker failure protection.

3 Auxiliary protection: A simple protection added to complement the performance of primary and backup protection or when the primary and backup protections are out of service.

Self-abnormal operation protection: protection against abnormal operating conditions of protected power equipment or lines.