For pre venting grounding failure fire of building some measures consisted of rolding ru led insulation level for electrical circuits and electrical equipments,practisin g equal potential connection for electrical device in building,ensuring good con nection of PE/PEN lines,providing special electrical leakage protector at the ge neral current source inlet of building,etc.

In this article the reasons of the fire caused by earthing fault in electrical design are discussed; at the same time from setting power leakage protection device, equal potential connection and other aspects corresponding countermeasures are proposed in order to make electrical design more reliable and safer.

Combining residential design regulation and related standard, discusses the adoption of grounding form, grounding fault protection, the choice of grounding device, and connection of equal potential.

The gas breakdown caused by the space charges in the large current enclosed bus bar wasstudied in this paper. The electric fields far away from the insulator and near the insulator were calculated separately. The equal potential line distributions around the insulator with different charge density weregotten.

In the light of new type tower and corresponding insulation coordination problem of Three-Gorges power transmission project,the live line replacement of middle-phase V-string insulators including the electrical clearance of tower head,combined gap,equal potential approach and operation method of replacement was discussed in detail.

The subsonic and transonic flow fields in two-dimensional Laval nozzles for all practical values of contraction ratio n1 expension ratio n2 and throat wall radius R* are obtained.The approach to the solut-on is to have it divied into two steps. As a first step, for the incompressible case, an exact solution of the nozzle flow with preassigned n1,n2 and R* is obtained by making use of the hodograph method. After that, for the corresponding compressible case, the problem is futher solved by making use of the streamline...

The subsonic and transonic flow fields in two-dimensional Laval nozzles for all practical values of contraction ratio n1 expension ratio n2 and throat wall radius R* are obtained.The approach to the solut-on is to have it divied into two steps. As a first step, for the incompressible case, an exact solution of the nozzle flow with preassigned n1,n2 and R* is obtained by making use of the hodograph method. After that, for the corresponding compressible case, the problem is futher solved by making use of the streamline perturbation method, using the streamlines and the equal potential lines of the incompressible flow solution as the curvilinear coordinates.The effects of the contraction and the expansion angles on the Laval nozzle flow, the transformation of the flow pattern of a Laval nozzle from the Taylor's type to the Meyer's type, the conditions for the occurance of the supersonic bubbles in the throat region of a Laval nozzle, and the governing parameters on the size and the shape of these bubbles are also discussed.

The recent achievments in potential theory have been applied to obtaining potential flow curves and equal potential curves in which density can be adjusted for complex solid boundaries. Those flow carves and equal potential curves are the two dimensional orthogonal numerical grid curves generated in this paper. In the special orthogonal curvilinear coordinate system that consists of the flow curves and equal potential curves, the scale factors of control equations in coordinate transformation...

The recent achievments in potential theory have been applied to obtaining potential flow curves and equal potential curves in which density can be adjusted for complex solid boundaries. Those flow carves and equal potential curves are the two dimensional orthogonal numerical grid curves generated in this paper. In the special orthogonal curvilinear coordinate system that consists of the flow curves and equal potential curves, the scale factors of control equations in coordinate transformation have been determined-the reciprocal of potential flow velocity(l/U), control equations can be directly numerically solved. The technique has been successfully applied to generating the orthogonal numerical grid of consequent bend and section of the Yangtze river, and the results of calculations are very satisfactory.

The equal potential method of calculating the effective resistance of symme- trical network is advanced and discussed.The application of the equal poten- tial method to some typical networks is also reported.