|4393430||Multi-phase failure detector|
Phase line currents of a polyphase power supply are rectified and applied to a common input terminal of a sine wave detector circuit to sense the presence of a signal current that is injected from a low voltage DC source into any time gaps that are formed...
|4370691||Protection apparatus for electric power transmission systems|
In a protection apparatus for a feeder (H) of an electric power transmission system compensation for mutual coupling between the feeder and another feeder (G) is controlled in dependence on the ratio of the zero sequence currents (IM, IN
|4354215||Selective safety device for the protection of a power distribution system|
In a selective safety device for the protection of successive power levels in a power distribution system, a current limiting switch is provided in each of the power levels and includes a current-limiting quick-switching contact which is so positioned at ...
|4351013||Circuit interrupter with multiple display and parameter entry means|
A circuit interrupter includes a microcomputer-based trip unit, and a display and control panel comprising a numeric display device and a plurality of legends associated with light-emitting diodes. The trip unit presents a sequential display of numeric va...
|4346422||Power-distribution network for telecommunication system|
A power-distribution network for the energization of a multiplicity of loads comprises a two-conductor trunk extending from a DC supply, a plurality of parallel primary branches connected to the trunk via respective first overload-responsive circuit break...
|4340921||HVDC Power transmission system with metallic return conductor|
A high voltage d.c. power transmission system utilizes a metallic return conductor for carrying return current between converters at opposite ends of the system. The return conductor is connected to earth ground at one end of the system and is otherwise i...
|4314301||Protective relaying devices|
In a protective relaying device comprising first and second potential transformer circuits for transforming voltages of an electric power system, first and second relaying elements are further provided for receiving the output voltages of the first and se...
|4293886||Network protector relay|
A network protector relay produces a close signal entirely from sequence components based on the magnitude and phase relationships between the positive sequence component of the phase-to-ground voltages on the network side of the protector and the positiv...
|4053816||Protection means for objects included in electrical power supply networks|
In an arrangement for level and sequence detection in a directional wave detector, which has a three-phase directional wave detector with two inputs per phase and three single phase and one three-phase tripping output and one three-phase blocking output, ...
|4004191||Method of reducing current unbalance in a three-phase power transmission line operating with one faulty phase|
A method for reducing current unbalance in the electric system of a three-phase A.C. power transmission line operating in an incomplete phase regime using the wires of the line and transformers electrically coupled thereto. A disconnected wire of the line...
|3959694||Electrical circuit protection apparatus|
An electrical circuit protective arrangement in which a reed spring relay has provided a back contact probe element associated with one of the springs and makes contact therewith when the normally closed springs are open and presents a gap with the associ...
|3952210||Grounding of a double-pole high voltage-direct current-transmission system|
A double-pole high-voltage direct-current transmission system is provided with two stations and an overhead line or cable, each of the stations having rectifier bridges connected in series from a positive line pole to a ground electrode and from the groun...
|3944885||Electric load restriction unit|
An electric load restriction device which conserves the secondary use of electricity during a period of a power shortage by causing selected load circuit breakers to open, in response to a change of frequency in the supplied primary electrical energy. The...