SU888217A2 - High-voltage device - Google Patents

Description

The invention relates to the construction of electrical devices, which are intended for terminating high-voltage electrical products, for example, for terminating cables, introducing cables into electrical equipment, and can be used as bushing insulators. According to the Main auth. No. 813513, a device is known comprising an insulated shielded conductor, an additional shield connected to the end of the conductor, and an insulating sleeve placed around the conductor between the shields, having annular shielded undercuts with toroidal sections at the ends, concentric to the conductor. The screens of the annular recesses of the insulating sleeve are connected to the screen with the conductor insulation and conductor 1, respectively. The disadvantages of this design are the increased values of the electric field and the insulation sleeve and the lack of uniform voltage distribution along the end device. The purpose of the invention is to increase the reliability of a high-voltage device by lowering the maximum voltage in an insulating sleeve and leveling the voltage distribution along the length of the device. To achieve this goal, in the proposed high-voltage device, a screened coating of a toroidal-shaped surface area, connected to a conductor from its end, is made of a material with a non-linear dependence of electrical resistance on the electric field strength with an irregularity index of not less than 1.7. As the specified material can be used the composition

based on silicon carbide, the dielectric constant of which is 9 | 8-10.2. The current-voltage characteristic (VAC) of silicon carbide is described by the equation I k U, where n is a measure of the non-linearity of the current-voltage characteristic.

The use of a nonlinear dielectric in the proposed device provides a qualitatively new technical effect due to the absence of direct contact of the shielding coating obtained from the composition based on this nonlinear dielectric with an electrically conductive screen on the conductor insulation.

FIG. 1 shows the end sleeve of the power cable} in FIG. 2 illustrates the distribution of the electric field of the coupling in the presence of a shielding coating of the composition based on silicon carbide (a) and in its absence (b). .

The high-voltage device (end coupling) contains a conductor 1 with polyethylene insulation 2, a shielding coating 3 from a composition based on silicon carbide, an insulating sleeve C made of polyethylene, covering the conductor directly in contact with its insulation and having non-ends concentric to the conductor annular grooves 5 and an electrically conductive screen 6 connected to the electrically conductive screen 7 superimposed on the conductor insulation.

From the diagrams shown in FIG. 2 it follows that the introduction into the design of the end sleeve of a shielding coating of a composition based on silicon carbide leads to a uniform distribution of voltage along the length

88217. four

an end sleeve, and in this case, only 30 applied voltage falls on the insulating sleeve, which in turn leads to

S a significant increase in the electrical strength of all "coupling instructions.

Tests of end-to-end cable couplings made according to the invention for a voltage of 110 kV showed positive results.

Electrical strength of terminations reaches k8 ac

(5 currents at a distance of 725 mm from the end of the shield along the insulation of the conductor to the point where the shielding coating of the silicon carbide-based composition is connected to the conductor.

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Claims (1)

1. USSR author's certificate No. 813513, cl. H 01 H 17/26, 1976. Ut.l