OVERCURRENT PROTECTIVE GEAR Russian patent published in 2002 - IPC

FIELD: electrical engineering; relay protection for users with dependent protection characteristic. SUBSTANCE: newly introduced in overcurrent protective gear are reference-voltage source and 2AND gate whose output is connected to input of final element; its first input is connected to output of OR gate and second input, to one of outputs of signal shaper that functions to record critical overcurrent; other outputs of signal shaper are connected to respective inputs of time-setting circuit and current sensor is inserted in series with circuit under protection. First inputs of signal shaper are connected to its output through voltage divider and its second ones, to respective levels of reference voltages. In this way device provides for protecting dc and ac power circuits and realizes single- valued current and time settings due to discrete principle of control. EFFECT: enhanced reliability. 6 cl, 1 dwg