The present invention relates to a transformer having a noise reduction structure. A tank (12) forms the exterior of the transformer (10). An inner space (14) filled with insulating oil is formed inside the tank (12). An iron core (20) is provided inside the tank (12) by a lower frame (16) and an upper frame (18), and coils (22) are wound around parts of the iron core (20) extending in the direction of gravity. An insulating sheet (24) is provided to encompass the surface of each of the coils (22), and has ridge portions (26) and groove portions (28), which are formed to extend in the height direction of the iron core (20). It is preferable that the side surfaces of the groove portions (28) are formed in parallel so as to face each other. The present invention as above minimizes the transfer of vibrations, generated from the coils (22), to the insulating sheets (24) provided on the surfaces of the coils (22) and removes a part of the vibrations since the vibrations coming out after having passed through the insulating sheets (24) are transferred to the insulating oil so as to cancel each other out. Therefore, the present invention can relatively reduce vibration and noise, which are generated from the transformer.

The present invention relates to a transformer having a noise reduction structure. A tank (12) forms the exterior of the transformer (10). An inner space (14) filled with insulating oil is formed inside the tank (12). An iron core (20) is provided inside the tank (12) by a lower frame (16) and an upper frame (18), and coils (22) are wound around parts of the iron core (20) extending in the direction of gravity. An insulating sheet (24) is provided to encompass the surface of each of the coils (22), and has ridge portions (26) and groove portions (28), which are formed to extend in the height direction of the iron core (20). It is preferable that the side surfaces of the groove portions (28) are formed in parallel so as to face each other. The present invention as above minimizes the transfer of vibrations, generated from the coils (22), to the insulating sheets (24) provided on the surfaces of the coils (22) and removes a part of the vibrations since the vibrations coming out after having passed through the insulating sheets (24) are transferred to the insulating oil so as to cancel each other out. Therefore, the present invention can relatively reduce vibration and noise, which are generated from the transformer.

The present invention provides an inductance coil comprising a magnetic core and a coil, wherein the coil is formed by winding a flat wire, and the flat surface of the wire is perpendicular to the axis around which the coil is wound. The coil is wrapped with an insulating adhesive tape and the tape is wound on the wire around an axis which is substantially in line with the direction along which the wire forming the coil extends, so as to form an isolation layer on the surface of the coil. Additionally, the present invention provides an electromagnetic device including the above inductance coil.

Disclosed is a basic module of a magnetic core of a wound electrical transformer. The basic module includes first and second windings placed atop one another and made of first and second materials, respectively. The first material is a crystal having a saturation magnetization ≧1.5 T and magnetic losses less than 20 W/kg in sine waves having a frequency of 400 Hz, for maximum induction of 1 T, and the second material is a material having an apparent saturation magnetostriction less than or equal to 5 ppm and magnetic losses less than 20 W/kg in sine waves having a frequency of 400 Hz, for maximum induction of 1 T. The cross-sections of the first winding and cross-sections of the second winding satisfy (S.sub.1/(S.sub.1+S.sub.3); S.sub.2/(S.sub.2+S.sub.4)) of the first material, having a high saturation magnetization, compared to the cross-section of both materials together, is 2%-50%.

An electronic brushless variable transformer. Variable autotransformers, use brushes, and as such, have moving parts requiring maintenance and periodic cleaning of the brushes. A variable transformer without brushes is advantageous in that it eliminates the cleaning and maintenance of brushes.

An electronic brushless variable transformer. Variable autotransformers, use brushes, and as such, have moving parts requiring maintenance and periodic cleaning of the brushes. A variable transformer without brushes is advantageous in that it eliminates the cleaning and maintenance of brushes.

A wire harness includes a wire portion having three wires arranged in the same direction, connectors connected to both end portions of the wire portion, a middle portion installed in an intermediate position of the wire portion between the connectors, a wire-side surge reducing section provided in the wire portion, a connector-side surge reducing section provided in each of the connectors, and a middle portion-side surge reducing section provided in the middle portion.

A coil-included terminal block allowing for a noise suppression effect. The coil-included terminal block includes: a terminal attachment member to which at least three terminal pairs are attached, each of the terminal pairs including a terminal and another terminal; and a plurality of coils configured to connect the terminals of the at least three terminal pairs to the respective other terminals of the at least three terminal pairs.

The noise suppression method of individual active noise reduction system comprises the steps that: (1) initial noise digital signals are received and converted to serve as input signals of a BP neural network; (2) the input signals are processed to generate secondary digital signals; (3) the secondary digital signals are output to a loudspeaker and secondary noise is generated; (4) remained noise digital signals obtained by overlapping the initial noise and the secondary noise are received; whether remained noise digital signals is continuously constant for the set times is judged; if yes, the secondary digital signals are kept outputting; (5) if not, BP neural network parameters are optimized and adjusted with the amplitude of the remained noise digital signals being minimum as the optimality principle; remained noise digital signals of previous step are served as new input signals and the step (2) is executed again.

Iron core vibration and transformer noise can be reduced by using, as a transformer iron core, an iron core formed by a stack of at least two types of grain-oriented electrical steel sheets that differ in magnetostriction by 2×10.sup.−7 or more when excited from 0 T to 1.7 T.