Patent ID: 8953295
Filing Date: 2015-02-10
Classification: H02H

Abstract:
1. A protection system for an IT electrical distribution system having a floating reference conductor and at least two electrical conductors, the protection system including: at least two input terminals for electrically connecting to an electrical power source that is upstream of the protection system; at least two output terminals for electrically connecting, via respective electrical conductors, to a load which is downstream of the protection system; a protection device for electrically connecting one or more of the input terminals to respective output terminals to allow a supply of electrical power from the source to the load, wherein the protection device is responsive to a fault signal for selectively electrically disconnecting at least one of the input terminals from the respective output terminal to prevent the supply of electrical power; and a sentinel unit for selectively generating the fault signal in response to a high impedance low current fault indicated by the current in the reference conductor being greater than a predetermined current threshold wherein the predetermined current threshold is less than about 10 mA.