A cooling fan variable-frequency control system for a power transformer includes a control device and a fan unit. The control device includes a microprocessor that is set with a first temperature range, a second temperature range higher than the first temperature range, and a fan switching time. The microprocessor is connected to a temperature sensor for detecting a temperature of an insulating oil in a power transformer. A variable-frequency controller and a fixed-frequency controller are connected to the microprocessor and are connected to a switching controller. The fan unit is connected to the switching controller and includes first and second fans. The microprocessor controls the switching controller according to the fan switching time to thereby control the variable-frequency controller to connect with the first fan or the second fan. The first fan and the second fan can operate at a fixed frequency and at a variable frequency.

A cooling fan variable-frequency control system for a power transformer includes a control device and a fan unit. The control device includes a microprocessor that is set with a first temperature range, a second temperature range higher than the first temperature range, and a fan switching time. The microprocessor is connected to a temperature sensor for detecting a temperature of an insulating oil in a power transformer. A variable-frequency controller and a fixed-frequency controller are connected to the microprocessor and are connected to a switching controller. The fan unit is connected to the switching controller and includes first and second fans. The microprocessor controls the switching controller according to the fan switching time to thereby control the variable-frequency controller to connect with the first fan or the second fan. The first fan and the second fan can operate at a fixed frequency and at a variable frequency.

An electromagnetic device comprises an enclosure, at least one winding in the interior of the enclosure, at least one wireless sensor attached to the winding for sensing at least one property or deficiency of the electromagnetic device and at least one active communication unit comprising transceiving circuitry and at least one antenna, wherein the transceiving circuitry is placed on the exterior of the enclosure and the least one antenna is placed inside the enclosure for communication with the at least one sensor, wherein the at least one sensor comprises at least one sensor attached to the winding, and wherein the at least one sensor attached to the winding is a printed electronic sensor comprising electronics printed on an insulating substrate, where the substrate faces the at least one winding.

An electrical device (10, 13), in particular a power transformer (13), a shunt reactor, or an on-load tap changer (10), comprises a housing (101, 131) that is filled or fillable with insulation oil (11, 11′); and a sensor (12) that comprises a piezo element (16) in the housing (101, 131) on a level with a minimum fill level (19, 19′) of the insulation oil (11, 11′); and an evaluation device (18) that is connected to the piezo element (16); wherein the evaluation device (18) is formed such that it can induce an oscillation of the piezo element (16);
and it can determine the fill level from a measurement of a characteristic of the oscillation, in particular the half-life period of the amplitude of the oscillation.

An electrical device (10, 13), in particular a power transformer (13), a shunt reactor, or an on-load tap changer (10), comprises a housing (101, 131) that is filled or fillable with insulation oil (11, 11′); and a sensor (12) that comprises a piezo element (16) in the housing (101, 131) on a level with a minimum fill level (19, 19′) of the insulation oil (11, 11′); and an evaluation device (18) that is connected to the piezo element (16); wherein the evaluation device (18) is formed such that it can induce an oscillation of the piezo element (16);
and it can determine the fill level from a measurement of a characteristic of the oscillation, in particular the half-life period of the amplitude of the oscillation.

To reduce the size of a magnetic circuit to be provided in a pulse power module for applying a high voltage in the form of a pulse across a pair of discharge electrodes which are disposed in a laser chamber of a gas laser apparatus, the magnetic circuit may include a magnetic core, an insulation member configured to contain a refrigerant flow path therein and cover the periphery of the magnetic core, and a winding wound around the insulation member.

To reduce the size of a magnetic circuit to be provided in a pulse power module for applying a high voltage in the form of a pulse across a pair of discharge electrodes which are disposed in a laser chamber of a gas laser apparatus, the magnetic circuit may include a magnetic core, an insulation member configured to contain a refrigerant flow path therein and cover the periphery of the magnetic core, and a winding wound around the insulation member.

A toroidal magnetic element. A plurality of coils is arranged in a toroidal configuration. Each coil may be a hollow cylinder, formed by winding a rectangular wire into a roll. The coils alternate with spacers, each of which may be a wedge. The coils may alternate in winding orientation, and the inner end of each coil may be connected, through a connection pin, to the inner end of an adjacent coil. Small gaps are formed between the coils and the wedges, e.g. as a result of each wedge having, on its two faces, a plurality of raised ribs, against which the coils abut. Cooling fluid flows through the gaps to cool the coils.

A toroidal magnetic element. A plurality of coils is arranged in a toroidal configuration. Each coil may be a hollow cylinder, formed by winding a rectangular wire into a roll. The coils alternate with spacers, each of which may be a wedge. The coils may alternate in winding orientation, and the inner end of each coil may be connected, through a connection pin, to the inner end of an adjacent coil. Small gaps are formed between the coils and the wedges, e.g. as a result of each wedge having, on its two faces, a plurality of raised ribs, against which the coils abut. Cooling fluid flows through the gaps to cool the coils.

An inductor for a boost converter in a hybrid vehicle includes a core, a coil winding, and an end cap. The coil winding is disposed about the core. The end cap is disposed over a first end of the inductor, overhangs the coil winding, defines a channel that is configured to receive fluid from a pump, defines at least one nozzle that is configured to direct fluid from an overhanging portion of the end cap and onto the coil, and defines a fluid reservoir that is in fluid communication with the channel and the at least one nozzle.