A SENTINEL UNIT FOR AN IT ELECTRICAL DISTRIBUTION SYSTEM HAVING A FLOATING REFERENCE CONDUCTOR

摘要

A protection system for an IT electrical distribution system (EDS) has a floating reference conductor and two electrical conductors in the form of an active conductor and a neutral conductor. System includes two input terminals for electrically connecting to an MEN electrical power source that is upstream of system. Two output terminals are electrically connected to an electrical load in the form of an electrical motor for a compressor of an upright freezer display. Motor is downstream of the system. A protection device, in the form of an MCB, electrically connects terminals to allow a supply of electrical power from source to motor. MCB is responsive to a fault signal at a port for selectively electrically disconnecting at least one of terminals to prevent the supply of electrical power. A sentinel unit selectively generates the fault signal at port in response to the current in conductor being greater than a predetermined threshold.