Misconnection detection device for ratio differential relay and current transformer

摘要

PURPOSE: To detect improper connection of CT accurately even in the case, wherein there is a differential current owing to the limit (error) of adjustment and the differential current cannot be distinguished as to whether the different current is caused by improper connection of the CT or by the differential current. CONSTITUTION: A phase changing means 31 sequentially changes the phase between I1 and I2 from an input converter 42 by 0 deg.-360 deg. by pushing a phase- changing test switch 30. The differential current value of I1 -I2 (=I3 ) corresponding to the change is operated with an operating means 32. The phase, where the differential current value of I1 -I2 (=I3 ) becomes the minimum value or the maximum value, is detected by a phase detecting means 33. A phase judging means 34 judges an improper connection when the detected phase is a specified value (for example, when the phase of the maximum value of the differential current value of I1 -I2 is 0 deg., the polarity is wrong), and the warning is generated in an output means 35.