Solid Insulated Switchgear with Local Semi-Conductive Coating
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Solution Overview
Problem
Conventional solid insulated switchgear with vacuum interrupters face challenges in maintaining sufficient insulation distance between contacts, leading to potential ground faults due to short insulation distances, and the concentration of electric fields, which complicates miniaturization and increases the risk of electric shocks.
Innovation Solution
A solid insulated switchgear design featuring a common actuator for both main circuit and earth switches, with air-insulated earth switches and a semi-conductive coating layer applied only to specific external parts of the switch enclosure, ensuring sufficient insulation distance and minimizing electric field concentration without increasing the switchgear size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the semi-conductive coating layer is coated on the entire part of the switch enclosure, then operator protection is improved, but electric field concentration occurs between conductive path and earth terminal, requiring increased space distance and surface distance
Solution Approach 1:
The semi-conductive coating layer is applied selectively only to the first external part of the enclosure (where the first fixed contactor is located) rather than the entire enclosure. This local application provides necessary operator protection near the earthed contact while avoiding electric field concentration that would occur with full-surface coating, thereby preventing the need to increase switchgear size.
Solution Approach 2:
The semi-conductive coating layer acts as an intermediary element that provides a controlled path for electric field distribution. By placing this intermediary only in specific locations (first external part), it protects operators from electric shock without creating the harmful electric field concentration that would result from complete enclosure coating.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively minimizes ground faults and electric field concentration, allowing for a more compact switchgear configuration while ensuring safe operation by maintaining adequate insulation distances and reducing the risk of electric shocks.
Implementation Method 1
a semi-conductive coating layer (SCC) is coated on the entire part of an enclosure of an arc extinguishing unit
Implementation Method 2
both a main circuit switch and an earth switch are configured as a vacuum interrupter
Data Source
AI summary
A switch according to the invention comprises a enclosure that is solid insulated and includes an electric power source side bushing portion, an electric load side bushing portion, and an accommodation body portion having air filled therein; a main circuit switch installed, for each pole, and having a vacuum interrupter that switches an electric power circuit by receiving a switching driving force from a common actuator; and an earth switch installed including a first fixed contactor to be earthed; a second fixed contactor electrically connected to the electric power source side connection conductor; and a movable blade connected to the common actuator, and movable to a first position for contacting the first fixed contactor and to a second position for contacting the second fixed contactor, by the switching driving force from the common actuator.