Abstract: A current sinking arrangement is provided that comprises a current sinking arrangement for connection to three phases of an AC grid, operable for reduction of short circuit fault currents in the AC grid, the current diverting arrangement comprising first, second and third phase arrangements, each including first and second grid terminals and a current diversion branch having a first impedance and a first switch and connected to a common floating conductor. On reception of a signal indicating a fault, which requires fault current reduction, a switching arrangement is arranged to make the first switches conducting so as to divert a portion of the fault current away from the AC grid fault location to the common floating conductor.

Abstract: An AC switching arrangement is provided with an energy transfer arrangement connected in parallel with a switching mechanism. The energy transfer arrangement comprises a capacitance arrangement and a diode arrangement. The switching mechanism normally closed in a first state, and on reception of a signal indicating the second state, the switching mechanism is arranged to open. When the switching mechanism is in the second state, the diode arrangement is arranged in each AC half cycle to enable energy (source energy, stored inductance energy, etc.) to transfer from the grid to the capacitance arrangement but to prevent energy transfer from the capacitance arrangement back to the grid.

Abstract: An AC switching arrangement is provided with an energy transfer arrangement connected in parallel with a switching mechanism. The energy transfer arrangement comprises a capacitance arrangement and a diode arrangement. The switching mechanism normally closed in a first state, and on reception of a signal indicating the second state, the switching mechanism is arranged to open. When the switching mechanism is in the second state, the diode arrangement is arranged in each AC half cycle to enable energy (source energy, stored inductance energy, etc.) to transfer from the grid to the capacitance arrangement but to prevent energy transfer from the capacitance arrangement back to the grid.

Abstract: The present invention provides a fault current limiter apparatus comprising: a fault current limiter including: a magnetically saturable core, at least one AC coil wound on at least a portion of the magnetically saturable core, and a magnetic biasing arrangement for magnetically biasing at least a portion of the magnetically saturable core; a source terminal for electrically connecting the fault current limiter to a power source, and a load terminal for electrically connecting the fault current limiter to a load, wherein the at least one AC coil of the fault current limiter is electrically connected between the source and load terminals, and wherein the fault current limiter has a first inductance in normal conditions and a second inductance in fault conditions; a first capacitance electrically connected between the source and load terminals, wherein the first capacitance is electrically connected in series with the fault current limiter, and wherein the first capacitance has a capacitance that is arranged to

Abstract: A three-phase current limiter (30) for an alternating current system includes an AC magnetic circuit having at least one AC coil (35R1, 35S1, 35T1) for each phase of a 3-phase AC supply wound on a saturable ferromagnetic core and configured to subject respective AC coils for each phase to a common magnetic flux, and a DC magnetic circuit (34a, 34b) for biasing the AC magnetic circuit into saturation at normal conditions. In use the AC coils are connected in series with a load and during alternate half cycles of the AC supply at least one of the AC coils produces a magnetic field that opposes a magnetic field of the DC magnetic circuit. The AC coils (35R, 35S, 35T) for each phase are configured so that at least one of the AC coils exhibits unbalanced magnetic impedance relative to remaining ones of the AC coils for each phase.

Abstract: A fault current limiter is provided for connection to a three phase AC supply. The fault current limiter comprises a first inductor for connection to a first phase of the AC supply; a second inductor for connection to a second phase of the AC supply; a third inductor for connection to a third phase of the AC supply. Each of the first, second and third inductors comprises a coil, and each of the coils of the first, second and third inductors is such that the self-reactance of each of the first, second and third inductors are substantially equal to a first reactance value. Furthermore, the coils of each of the first, second and third inductors are arranged such that the mutual reactance between each pair of inductors is substantially equal to a second reactance value, and the second reactance value is substantially equal to the first reactance value.

Abstract: A current limiting device (30, 40, 50, 60) comprising for each phase of an AC supply a closed magnetic core (31) of reduced volume and mass having first and second pairs of opposing limbs (32a, 32b; 33a, 33b), and at least one AC coil (35a, 35b) enclosing opposing limbs (33a, 33b) of the magnetic core (31) and adapted for series connection with a load. A superconducting DC bias coil (34) encloses a limb) (32a, 32b) of the magnetic core (31) for saturating each of the opposing limbs (33a, 33b) in opposite directions by the bias coil (34). Under fault conditions, the AC flux in at least one limb counteracts the DC bias flux, bringing the limb out of saturation. Preferably, current is reduced in the DC bias coils thus bringing both opposing limbs of the core out of saturation.

Abstract: A three-phase current limiter (30) for an alternating current system includes an AC magnetic circuit having at least one AC coil (35R1, 35S1, 35T1) for each phase of a 3-phase AC supply wound on a saturable ferromagnetic core and configured to subject respective AC coils for each phase to a common magnetic flux, and a DC magnetic circuit (34a, 34b) for biasing the AC magnetic circuit into saturation at normal conditions. In use the AC coils are connected in series with a load and during alternate half cycles of the AC supply at least one of the AC coils produces a magnetic field that opposes a magnetic field of the DC magnetic circuit. The AC coils (35R, 35S, 35T) for each phase are configured so that at least one of the AC coils exhibits unbalanced magnetic impedance relative to remaining ones of the AC coils for each phase.

Abstract: A current limiting device (30, 40, 50, 60) comprising for each phase of an AC supply a closed magnetic core (31) of reduced volume and mass having first and second pairs of opposing limbs (32a, 32b; 33a, 33b), and at least one AC coil (35a, 35b) enclosing opposing limbs (33a, 33b) of the magnetic core (31) and adapted for series connection with a load. A non-superconducting DC bias coil (34) typically formed of copper encloses a limb (32a, 32b) of the magnetic core (31) for saturating each of the opposing limbs (33a, 33b) in opposite directions by the bias coil (34). Under fault conditions, the AC flux in at least one limb counteracts the DC bias flux, bringing the limb out of saturation. Preferably, current is reduced in the DC bias coils thus bringing both opposing limbs of the core out of saturation.

Abstract: A current limiting device (30, 40, 50, 60) comprising for each phase of an AC supply a closed magnetic core (31) of reduced volume and mass having first and second pairs of opposing limbs (32a, 32b; 33a, 33b), and at least one AC coil (35a, 35b) enclosing opposing limbs (33a, 33b) of the magnetic core (31) and adapted for series connection with a load. A superconducting DC bias coil (34) encloses a limb) (32a, 32b) of the magnetic core (31) for saturating each of the opposing limbs (33a, 33b) in opposite directions by the bias coil (34). Under fault conditions, the AC flux in at least one limb counteracts the DC bias flux, bringing the limb out of saturation. Preferably, current is reduced in the DC bias coils thus bringing both opposing limbs of the core out of saturation.

Abstract: A catalytic gas radiant tube heater, and a method for its use. A radiant tube encloses a catalyst tube containing a catalyst on a catalyst support. Air and a gaseous hydrocarbon fuel diffuse into the catalyst support and react on the catalyst surfaces. The reaction heats the catalyst tube, causing the catalyst tube to emit infrared radiation, which heats the radiant tube from within, causing the radiant tube to emit infrared radiation. The infrared radiation emitted by the radiant tube is directed in the desired direction by a reflector. The preferred catalyst is cobalt chromium oxide spinel.

Abstract: A catalytic heater includes a catalyst, for the combustion of a gaseous hydrocarbon in air, supported on a catalyst support. Fuel diffuses into the catalyst support from one (proximal) side. Air diffuses into the catalyst support from the other (distal) side. The catalytic combustion of the fuel heats the catalyst support. The resulting infrared radiation from the distal side of the catalyst support is directed at an object to be heated, for example the fluid chamber of a boiler. A modular boiler includes several catalytic heaters, with the distal sides of their catalyst supports facing a chamber wherethrough a fluid such as water is conducted and heated by the infrared radiation from the heaters.

Abstract: An apparatus and method for printing a marble motif. The apparatus comprises a holder, including a hand gripping portion, a hollow cylindrical roller rotatably mounted in the holder defining a first set of perforations, and a partition disposed within the roller to divide the hollow of the roller into a plurality of compartments adapted to receive different colored paints. The partition defines a second set of perforations to permit limited fluid communication between the compartments to partially mix the paints. A porous absorbent material is positioned over the roller and in fluid communication with the first set of perforations. The method comprises separately storing a plurality of different colored paints in the compartments, and rolling the porous absorbent material over a surface to cause the partially mixed paints to print a marble motif on the surface.