中文摘要：

针对12kV配电网终端用户变电站、户内外环网柜等进线开关柜的特点．设计了一种基于16位单片机控制的多功能终端用户开关柜微机保护装置。该保护装置自具电源，基于热量累积原理实现快速高精度相电流反时限保护方法，实现对相电流和零序电流三段式保护。根据主回路断相和CT断线故障时相电流符号特征及电流值特点来识别故障类型。故障电流录波，液晶显示，CAN总线通讯接口与其它保护装置及上位机之间远程通讯。实验结果表明。动作时间及电流动作值精度在2％以内．保护装置运行稳定可靠。

英文摘要：

Aiming at the incoming line switchgear cabinet characteristics of 12 kV distribution network terminal substation and main unit, this paper presents a multifunctional digital protection set of terminal user switchgear based on 16-bit microprocessor. The power of the protector is supplied by itself from the CT. Based on thermal cumulate principles, a rapid and high precision inverse-time phase-sequence over＇current protection is implemented. Three stages phase-sequence current and zero-sequence current protection can be implemented. Main circuit phase-lack fault and CT wire-break fault can be identified by the current signs and values. Fault current recording is displayed by liquid-crystal and current curve diagram can be transmitted to PC and therefore analyzed. It can communicate with other protection apparatus based on CAN field-bus. Test results show that time duration and current operating value precision are less than 2%, and the functions of the protection device are reliable.