Patent ID: 8547112

Claim:
A method for monitoring a dielectric state of high voltage equipment with capacitive insulation using a monitoring system, the method comprising: directly and continuously measuring a leakage current ( 3 ) of the insulation ( 2 ), and comparing the leakage current to a limit value programmed by a user and activating an alarm for serious deterioration of the insulation ( 2 ) if the leakage current exceeds the limit value; counting a time period during which the leakage current ( 3 ) is above that limit value, suppressing any alarm emission until the counted time period reaches a first time delay value programmed by the user, allows an alarm emission after the counted time period reaches the first time delay value, and, if the leakage current ( 3 ) returns to a value under the limit value during the counting operation interrupting the time counting and reset to zero; checking a consistency of the leakage current measurement through a comparison of a change ( 3 MA) in individual leakage currents ( 3 FA, 3 FB, 3 FC) against a change ( 3 MS) in a vector sum ( 3 S) of the leakage currents ( 3 FA, 3 FB, 3 FC), and calculating a vectorial difference ( 3 D) between the change ( 3 MA) in the leakage current ( 3 FA) and the change ( 3 MS) in the sum current ( 3 S); permitting the emission of the deteriorated condition alarm if the vectorial difference ( 3 D) is smaller than a permitted difference value; blocking the emission of the deteriorated condition alarm if the vectorial difference ( 3 D) is greater than the permitted difference value; counting a time during which the vectorial difference ( 3 D) is above a permitted difference value, and activating a monitoring system failure alarm if the time during which the vectorial difference ( 3 D) is above the permitted difference reaches a second time delay value and resetting the time counting value to zero if the vectorial difference ( 3 D) returns to a value under the permitted difference value.