FIELD: electric engineering. SUBSTANCE: device has zero sequence current transformers 3 and 4 which are located on connections 1 and 2, current-to-direct-voltage converters 5 and 6, integrators 7 and 8, threshold gates 9 and 10, matching gates 11 and 12, pulse expanders 13 and 14, final-control units 15 and 16, NOR gate 17, NOT gate 18, OR gate 19 and prohibition gate 20, start unit 21, low-frequency locking unit 22, zero sequence voltage transformer 23, main and additional reference voltage sources 24 and 25, closing gate 26, breaking gate 27, diode assembly 28. OR gate, NOT gate, prohibition gate, low-frequency locking unit, diode assembly, additional reference voltage source, closing and breaking gates are introduced to accomplish the goal of invention. EFFECT: increased functional capabilities, increased precision of detection of destroyed connection. 1 dwg
