METHOD OF INSULATION SERVICE LIFE MONITORING FOR ALTERNATING CURRENT HIGH-VOLTAGE EQUIPMENT Russian patent published in 2014 - IPC H02H9/04 

FIELD: electricity.

SUBSTANCE: method evaluates remaining life by means of subtraction from it of the life part determined at each voltage half-period as the ratio of a half-period duration to the permitted time of insulation stating under effective voltage. The initial service life of insulation is accepted as 1. The novelty of the method lies in operations allowing increase in accuracy of determination of the effective voltage value (nonsinusoidal, in the general case) against voltage measurements at equal time intervals. In order to achieve the above goal, the voltage measurements are converted to intermediate signal samples by their squaring, the intermediate signal is subject to additional averaging, weighing with a coefficient of ј the sum of its current sample and three previous samples shifted in regard to the current sample to the fixed time intervals equal to 1/6, 1/2, and 2/3 or 1/4, 1/2 and 4/5 of the sample number within the rated frequency period of the measured voltage, if the above number of samples is divided evenly by 6 or 20 respectively. The effective value of voltage is defined by square-rooting of the averaged amount of the intermediate signal samples for the number of measurements during the period of electrical voltage.

EFFECT: improving accuracy of the remaining life determination for insulation and provision of timely measures to maintain operability of the protected high-voltage equipment during overloads by the voltage limitation or decrease or by its shutdown.

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