正反转电机缺相保护功能的实现及决策表分析测试

摘要

In industrial production, motor has a special operating mode for forward or reverse rotation, relative to for-ward rotation, reverse rotation current that measured by protection device showed negative sequence characteristics, it will lead to negative sequence protection mis-operation, therefore, reverse rotation open-phase protection can’ t be a-chieved through negative sequence protection function.In order to identify the motor open-phase failure, and ensure safe and reliable operation of the motor, combining with the variation characteristics of three-phase current when the open-phase runtime, and use internal programmable function modules in protection device to achieve open-phase pro-tection logic, but no-load operation of the motor occasionally appears open-phase protection tripping when reverse rota-tion,and affect the continuity of production.In order to find the cause of the problem, use decision table which be-longs to black box testing method to analyze the logic of open-phase protection, and found that under certain condi-tions combination can trigger open-phase protection mis-operation.According to the characteristic of another two phase current will increase when the motor open-phase runtime, the original open-phase protection logic has been improved, and has a comprehensive test by using decision table, and the protection mis-operation no longer appears when motor forward or reverse rotation after using the improved protection logic.%工业生产中电机存在正反转的特殊运行方式，在反转时保护装置测量到电流相对正转时而言，呈现负序特性，导致负序保护功能误动作，因此通过负序功能无法实现反转时的缺相保护功能。为了识别电动机缺相故障，保证电机的可靠安全进行，结合缺相运行时的三相电流变化特征，利用保护装置内部的可编程功能模块实现缺相保护逻辑，但空载运行的电机反转时偶尔会出现缺相保护跳闸，影响生产的连续性。为了查找问题原因，使用黑盒测试中的决策表法对缺相保护逻辑进行了分析，分析发现在特定的条件组合下能够触发缺相保护误动。根据电动机缺相时另外两相电流增大的特征，对原缺相保护逻辑进行了改进，并使用决策表法进行了全面测试，采用改进后保护逻辑的电机正反转时均未再出现保护误动。