METHOD FOR LOOSE JOINT DETECTION IN MEDIUM VOLTAGE SWITCHGEARS AND MEDIUM VOLTAGE SWITCHGEAR ITSELF

摘要

The invention relates to a method for loose joint detection in medium voltage switchgears with busbar joints, circuit breaker upper and lower spouts, and cable connection joints, arranged in an air insulated housing, and medium voltage switchgear itself, according to the preamble of claim 1 and claim 9. In order to create an effective loose joint detection with lower operating expense, but with high performance and accuracy, the invention is, that the actual temperatures are measuredat phase (L1) as temperature (T1),at phase (L2) as temperature (T2),at phase (L3) as temperature (T3), at predefined critical points, such asat the busbar joints, and/or at the circuit breaker upper spouts, and/or at the circuit breaker lower spouts, and/or the cable connection,and that the concering temperatures are compared in the following logical dependency $\mathrm{Ti}\left(\mathrm{Tj}+\mathrm{dT}\right),\mathop{\mathrm{image}}$ with i ≠ jpermutated with i from 1, 2, 3and j from 1, 2, 3,and that alarm is set if the aforesaid condition is fulfilled.