(1) Power equipment and wiring in civil buildings should be equipped with short circuit fault and abnormal operation relay protection device. Protection of power equipment and short-circuit fault should be the main protection and backup protection, if necessary, additional protection can be added â‘ main protection: to meet the system stability and equipment safety requirements, the fastest speed can be selectively cut off the protection of equipment and line protection. â‘¡ backup protection: the main protection or circuit breaker refused to move. Used to cut off the protection of the fault. Backup protection can be divided into two kinds of far backup and backup a. Far backup: When the main protection or circuit breakers refused to move, by the protection of adjacent power equipment or lines to achieve backup. b. Proximity Backup: When the main protection is refusing to move, backup protection is realized by another set of protection of the power equipment or the line; when the circuit breaker refuses to be actuated, the backup is realized by the circuit breaker failure protection. â‘¢ Auxiliary protection: simple protection added to supplement the performance of main protection and backup protection or when main protection and backup protection are out of operation. From abnormal operation protection: It is the protection of the protection of the abnormal operation status of power equipment or lines. Automatic Screw Locking Machine editor control,simple and convenient operation,professional screw system SINGSUN ELECTRONIC SCIENCE & TECH CO.,LTD , https://www.singsunautomatics.com