Axial currents of power frequency flowing in filaments parallel to cylindrical shells, of finite thickness, give rise to eddy currents in the conducting material of the shell due to proximity effect. Axial currents flowing in the shell give rise to skin effect. The distribution of both these currents is determined analytically by solving the differential equation for penetration of currents in the conducting material and appropriately applying boundary conditions. The phase difference of the current density at any point of the crossection and the loss are also determined. Both, shell and current filament are assumed to have an infinite length. The material of the shell is considered to be nonmagnetic.

Eddy Current Distribution in Cylindrical Shells of Infinite Length Due to Axial Currents Part II: Shells of Finite Thickness

A centering support for a double-containment piping assembly has a body portion including an inner surface defining a central aperture for receiving and supporting the inner pipe within the outer pipe, and the inner surface is defined by a first radius of curvature. A plurality of support lugs are spaced apart from each other and project outward from the body portion, and each support lug defines an outer support surface for contacting the outer pipe. The support lugs also define corresponding recessed surfaces extending between adjacent support lugs, and each recessed surface is defined by a second radius of curvature substantially concentric with the first radius of curvature.

Double-containment piping supports for improved annulus flow

A multiphase high-voltage pressurized gas insulated electrical power transmission system for underground applications incorporating a central conductor for each phase, each central conductor being mounted within a grounded conductive housing concentrically arranged with its associated central conductor with the concentric alignment being maintained by insulating spacers. Each of the central conductors and associated housings for the multiphase system are mounted within a steel housing and arranged in a triangular or delta configuration. Conductors of adjacent sections are joined by suitable dielectrically shielded plug-in contact assemblies which provide for electrical continuity between adjacent central conductors of the multiphase bus assembly sections. The concentric grounded housings are preferably perforated to facilitate egress of contaminating particles which may be present within the interior of each grounded housing. The outer steel housing sections are joined, end to end by butt joint welding techniques. In another preferred embodiment, the grounded aluminum housings surround only selected portions of their associated inner conductors and single ground screen means are employed in each housing section for collection of contaminating particles which may be present within the assembly.

High-voltage pressurized gas-insulated power transmission systems

Short-Circuit Forces in Isolated-Phase Busses [includes discussion]

An electric bus comprises a pair of adjacent bus portions, each comprising a tubular sheath and a conductor within the sheath spaced and electrically insulated from the sheath. A currentcarrying joint electrically connects the conductors in series and comprises: (a) two spaced-apart ball and socket connections electrically connected in series with each other, and (b) a sliding connection electrically in series with the ball and socket connections for allowing relative movement between the conductors in a direction longitudinally thereof. A tubular enclosure for the joint is radially spaced therefrom, is joined to the sheaths at its opposite ends, and is constructed to allow for axial, transverse, and rotational movement of the sheaths with respect to each other.

Electric bus with joint for accommodating earthquake-produced motion of parts

This paper describes a bus with electrically continuous phase enclosures interconnected at both ends. Currents in the shielding loop thus formed reduce external magnetic flux to less than one tenth the amount experienced with a discontinuous sheath. Circulating currents in nearby metallic loops are greatly reduced thereby, making joint insulation and banding of steel beams unnecessary. Over-all sheath losses are practically unchanged, for shielding current losses are approximately balanced by substantial elimination of sheath eddy-current losses. Analytical predictions are confirmed by tests.

Minimizing the Magnetic Field Surrounding Isolated-Phase Bus by Electrically Continuous Enclosures

Non-segregated metal clad bus duct with insulating frames for supporting bus bars

Discloses a liquid-cooled electric bus comprising a pair of hollow bus bar sections interconnected by a removable hollow disconnecting link. The interiors of the bus bar sections and the link are hydraulically interconnected to permit liquid coolant to flow between said bus bar sections via said link. Each bus bar section has a flow-blocking barrier therein and a bypass circuit bypassing the barrier comprising a pair of flexible lines of electrical insulating material and a shutoff valve interconnecting said lines.

Liquid-cooled bus containing a disconnecting link

Adjustable joint structure

Discloses a power system in which first, second and third single-phase transformers have their primary windings connected in delta. A spare transformer is disposed physically adjacent the third transformer and is provided with switching means for connecting its primary winding to the bus in a manner that enables the spare to serve as a replacement for the third transformer. Additional switching means is provided for connecting the primary winding of the third transformer to the bus in a way that enables the third transformer to serve as a replacement for the second transformer, should such replacement be necessary. Still additional switching means is provided for connecting the primary of the second transformer to the bus in a way that enables the second transformer to serve as a replacement for the first transformer, should this latter replacement be necessary.

Nathan Swerdlow

Papers

Minimizing the Magnetic Field Surrounding Isolated-Phase Bus by Electrically Continuous Enclosures

Non-segregated metal clad bus duct with insulating frames for supporting bus bars

Liquid-cooled bus containing a disconnecting link

Adjustable joint structure

Spare transformer connecting means