The present disclosure provides a noise/vibration reduction device for transformers. An inner space 12 may be formed inside a tank 10 constituting the exterior of a transformer. The noise/vibration reduction device 20 may be installed on inner surfaces of tank side walls 14 constituting the outer surfaces of the tank 10. The reduction device 20 may include a plurality of support members 26, 28, 30 installed between a plurality of through hole plates 32, 34, 36, whereby a first space 38, a second space 40, and a third space 42 may be formed between the through hole plates 32, 34, 36 and the tank side walls 14. A first through hole 32′, a second through hole 34′, and a third through hole 36′ may be formed in the through hole plates 32, 34, 36, respectively. By varying a diameter (D) and a length (T) of the through holes 32′, 34′, 36′ and a distance (L) between the through holes 32′, 34′, 36′, noise having different frequencies may be removed from each of the through hole plates 32, 34, 36.

The present disclosure provides a noise/vibration reduction device for transformers. An inner space 12 may be formed inside a tank 10 constituting the exterior of a transformer. The noise/vibration reduction device 20 may be installed on inner surfaces of tank side walls 14 constituting the outer surfaces of the tank 10. The reduction device 20 may include a plurality of support members 26, 28, 30 installed between a plurality of through hole plates 32, 34, 36, whereby a first space 38, a second space 40, and a third space 42 may be formed between the through hole plates 32, 34, 36 and the tank side walls 14. A first through hole 32′, a second through hole 34′, and a third through hole 36′ may be formed in the through hole plates 32, 34, 36, respectively. By varying a diameter (D) and a length (T) of the through holes 32′, 34′, 36′ and a distance (L) between the through holes 32′, 34′, 36′, noise having different frequencies may be removed from each of the through hole plates 32, 34, 36.

A coil component includes: a coil embedded in a substrate body and having a winding part constituted by a wound conductor; wherein the substrate body has: a first region sandwiched between one end surface of the substrate body and a plane parallel with the one end surface and running through a portion of a first external electrode farthest away from the one end surface; a second region sandwiched between another end of the substrate body and a plane parallel with the another end surface and running through a portion of a second external electrode farthest away from the another end surface; and a third region between the first region and the second region; and the winding part is provided in the third region, and also in the first region where it is wound by one turn or more.

Provided is a reactor including a coil having a pair of winding portions; and a ring-shaped magnetic core, the magnetic core including: a pair of inner core portions arranged inside of the winding portions; and a pair of outer core portions respectively arranged outside of one end and outside of another end in an axial direction of the winding portions, the reactor including a non-magnetic reinforcing member that is arranged between the pair of winding portions and is coupled to the inner end surfaces of the pair of outer core portions. An axial rigidity of the reinforcing member is 2×10.sup.7 N/m or more. Here, the axial rigidity is a value obtained by multiplying the cross-sectional area of the reinforcing member perpendicular to the axial direction of the winding portions and the Young's modulus of the reinforcing member, and dividing the result by the length of the reinforcing member.

An elastic matrix determination method and a vibration analysis method for a laminated iron core, with which it is possible to optimally determine an elastic modulus of a laminated iron core. When a vibration analysis of a laminated iron core obtained by laminating steel sheets is performed by using a configuration expression indicating a relationship between stress and strain in a matrix display by using an elastic matrix, a shear modulus in two surfaces including a laminating direction of the laminated iron core included in the elastic matrix in the configuration expression is determined in consideration of slip between laminated steel sheets.

Provided is a method for manufacturing a grain-oriented electrical steel sheet. The method comprises: hot rolling a slab to obtain a hot rolled sheet; subjecting the hot rolled sheet to hot band annealing as necessary; subjecting the hot rolled sheet to cold rolling; subjecting the cold rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component onto a surface of the decarburization annealed sheet and subjecting the decarburization annealed sheet to final annealing to form the forsterite film; and applying an insulating coating treatment liquid onto the final annealed sheet and subjecting the final annealed sheet to flattening annealing to form a tension-applying insulating coating. A difference in total tensions between one and opposite surfaces of the sheet is less than 0.5 MPa. A difference in tensions between the forsterite films in one and opposite surfaces of the sheet is 0.5 MPa or more.

Provided is a brace apparatus for a transformer tank and a method for determining the length thereof. The brace apparatus is mounted on a transformer tank so as to reinforce the transformer tank. The brace apparatus has a brace main body forming the exterior thereof, and in order to block the occurrence of resonance in an inner space of the brace main body, the length of the brace main body is set to be at a value at which resonance does not occur in the inner space, or a partition plate is provided to the brace main body so as to block the occurrence of resonance. In present invention, the length of the brace apparatus may be set by means of a simple configuration, thereby enabling the prevention of noise from occurring due to resonance.

Provided is a brace apparatus for a transformer tank and a method for determining the length thereof. The brace apparatus is mounted on a transformer tank so as to reinforce the transformer tank. The brace apparatus has a brace main body forming the exterior thereof, and in order to block the occurrence of resonance in an inner space of the brace main body, the length of the brace main body is set to be at a value at which resonance does not occur in the inner space, or a partition plate is provided to the brace main body so as to block the occurrence of resonance. In present invention, the length of the brace apparatus may be set by means of a simple configuration, thereby enabling the prevention of noise from occurring due to resonance.

A magnetic component in a power conversion device includes a bobbin that has a rod-shaped central portion and holds a core and a winding member. The central portion of the bobbin is configured to protrude from the winding member by a predetermined length and to come into contact with a cooling member in a state of being inserted into the winding member to penetrate the core having an annular shape. A filler is filled between the winding member and the cooling member in a state where the central portion comes into contact with the cooling member.

A magnetic component in a power conversion device includes a bobbin that has a rod-shaped central portion and holds a core and a winding member. The central portion of the bobbin is configured to protrude from the winding member by a predetermined length and to come into contact with a cooling member in a state of being inserted into the winding member to penetrate the core having an annular shape. A filler is filled between the winding member and the cooling member in a state where the central portion comes into contact with the cooling member.