Patent RU-2734107-C1 (RU)
Title: Method of protecting from receiving side two parallel lines with one-sided supply
Inventor: POLISHCHUK VLADIMIR IOSIFOVICH
IPC: H02H7/22
Filed: 2020-03-17
Granted: 2020-10-13
Abstract: FIELD: electricity. 
     SUBSTANCE: use in power engineering for protection of parallel lines against short circuits. Method for protection from receiving side of two parallel lines with one-sided supply, in which instantaneous values of currents i 1  at first and i 2  on second line are measured in positive or negative half-wave of current at current rise, i 1  is compared to positive or negative half-wave with preset value of current i ec , and when current i 1  reaches current value i ec , while measuring instantaneous value of current i 1 , beginning to count time t 1  to the moment, when to next positive or negative half-wave at current increase, value of current i 1  reaches specified value of current i ec , measured time t 1  is compared to first and second preset time values t ec1  and t ec2 , and if value t 1  is greater than a given time t ec1 , but less than a given time t ec2 , then the time count is repeated until the time value t 1  is greater than or equal to the preset time t ec1  or the time value t 1  becomes less than or equal to the preset time t ec2 , then if one of these inequalities is satisfied, then disconnecting the first line, removing it for repair and after repair is included in operation, in the same way, with time reference t 1,  time t 2  is counted when current i 2  reaches the second line with a given current value i ec  until the moment, when in next positive or negative half-wave at current rise value of current i 2  reaches i ec , measured time t 2  is compared with first and second preset time values t ec1  and t ec2 , and if value t 2  is more than preset time t ec1 , but less than a given time t ec2 , the time count is repeated until the time value t 2  is greater than or equal to a given time t ec1  or the time value t 2  becomes less than or equal to a given time t ec2 , then if one of these inequalities is satisfied, then switching off second line, brought out for repair and, after repair, is put into operation, simultaneously with switching on deactivated second or first line in operation, when first or second line is in on position, starting to count time t 3  from moment, when current i 1  or i 2  reaches preset value of current i ec  in positive or negative half-wave of current till moment, when current i 2  or i 1  becomes equal to value of preset current i ec , comparing t 3  with third preset time t ec3 , and if time t 3  is greater than or equal to value of preset time t ec3 , both lines are switched off, then through time t 4  includes first or second line, then after preset time t 5  after switching on its position is fixed, and if it is in on position, then second or first line is brought out for repair, if it is in disconnected position, then the second or the first line is switched on, and the first or the second line is brought out for repair. 
     EFFECT: detecting and reducing the time of disconnection of the damaged line when one of the lines is switched on for short-circuit during operation of the other line. 
     1 cl, 1 dwg