METHOD FOR DIAGNOSING CONDITION OF 0.4 kV SUPPLY LINE Russian patent published in 2023 - IPC H02J3/26 G01R31/08 

FIELD: electrical engineering.

SUBSTANCE: diagnosing the condition of a 0.4 kV network with a grounding system with a combined neutral conductor TN-C. According to the method for diagnosing the state of a 0.4 kV supply line, the current in the neutral combined conductor and the grounding device is continuously measured, the current in the neutral combined conductor and the grounding device is measured at intervals of 15 minutes and their value is stored, continuously measured and stored at 15-minute intervals effective values of current and voltage of phases A, B and C of the line on the consumer side and record the values of the normal mode of the network, calculate the current resistances of the protective and working neutral conductors and calculate the current ratio of these resistances, calculate the ratio of the current in the neutral protective conductor to the current in the neutral working conductor and compare it with the current ratio of their resistances, and if they are equal, they draw a conclusion about the normal mode of the network, and in the case of inequality, they draw a conclusion about the occurrence of an emergency mode and identify the cause of its occurrence, namely, they compare the ratio of the current in the neutral protective conductor to the current in neutral working conductor with the maximum permissible change in this ratio, compare the current value of the current in the neutral working conductor with the previous one, measured over a 15-minute time interval, and if it is lower than the previous one, conclude that there is a malfunction of the neutral combined conductor, and in the absence of current in the zero working conductor, they conclude that it is broken if the ratio of the current in the zero protective conductor to the current in the zero working conductor is below the maximum permissible change in the ratio of their resistances, but above this ratio in normal mode, compare the current value of the current in the zero protective conductor with the previous one, measured at 15-minute time interval, and if it is lower than the previous one, they conclude that there is a malfunction of the neutral combined conductor, and if there is no current in the neutral protective conductor, they conclude that it is broken; if the current value in both neutral conductors is 0, then they conclude that the connection is broken with a grounding device and a neutral conductor, if an increase in current in the grounding device is recorded to a value corresponding to a single-phase ground fault, compare the current voltage value in the phase conductors with the previous ones measured over a 15-minute time interval, and if a decrease in voltage is detected in one of the phase conductors, the sum of instantaneous current values in the phase and both neutral conductors is calculated, and if it is not equal to zero, a conclusion is made about a single-phase ground fault of the corresponding phase conductor; signaling of the occurrence of an emergency mode and the type of emergency situation is carried out on site and by means of remote notification to the user.

EFFECT: ability to identify the type of emergency mode and the reasons for its occurrence.

1 cl, 1 dwg