GB1446937A - Automatic systems for locating a defective portion of a feeder line of a medium voltage electrical power distribution network and for isolating the defective portion from the network - Google Patents

Abstract

1446937 Protective arrangements ELECTRICITE DE FRANCE (SERVICE NATIONAL) 8 Nov 1973 [9 Nov 1972 2 Nov 1973] 51884/73 Heading H2K An automatic system, Fig. 2, for isolating a faulty section T4 of a medium voltage electrical power distribution network and restoring service to the rest of the network comprises, between a normal and an auxiliary power source 51, 52 at opposite ends of a network divided into two parts by a cut-out point 129, distribution stations P 1 to P 5 and C 1 to C 3 , provided with fault detectors and connected in the network, each station being provided with cut-out switches for automatically breaking the network in case of a fault and isolating the faulty section, power being fed to stations on either side of the faulty section then from the normal and auxiliary power sources respectively. At least some stations, Fig. 3, have in association with the cut-out switches a service restoration device 110 comprising a transmitter 114 armed by a fault detector 112 in the absence of voltage in the network and actuated by fault detectors 116, 117 when fault current passes to deliver a position pulse at a time instant defined by a time delay 120 dependent upon its position in the network and a receiver 115 responsive to such position pulses to pass them to selectors 123, 124 associated respectively with the normal and auxiliary power sources, which selectors step in accordance with the received position pulses to a final position which defines the faulty section of the network and causes operation of the appropriate cut out switches to isolate the faulty section. Power is then restored to the rest of the network. The signal from the transmitter 114 is an audio frequency pulse which is fed to the low voltage terminals of the power transformer 105 of the distribution station. The final position of the selectors may be used to control a light signal which indicates the position of the fault in the network. Reversing means are associated with the selectors to take account of changes in direction of power flow. Embodiments of the invention applied to feeder lines are described, and in one case, Fig. 8, not shown, a third power source is available.