Vacuum Interrupter for Fast Earthing Arc Interruption

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Solution Overview

Problem

Existing solutions for rapid grounding of high voltage lines in metal-enclosed electrical substations are bulky, costly, and inefficient in extinguishing secondary arcs, particularly for high voltage GIS systems, as they do not optimize the breaking function, size, and operating energy effectively.

Innovation Solution

A fast earthing device with breaking capacity is integrated into the GIS substation, combining a medium voltage vacuum switch with a fast earthing circuit, where the vacuum interrupter performs dielectric isolation and interrupts secondary arc currents, while the fast earthing device ensures dielectric strength and low-energy breaking capacity in a compact form.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gas-insulated circuit breakers are used for rapid grounding, then the breaking capacity is sufficient, but the device becomes very bulky

Engineering Contradiction:

Improvebreaking capacityVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The device is divided into two functional segments: a fast earthing circuit for rapid grounding and a vacuum interrupter for arc interruption. This segmentation allows each component to be optimized for its specific function, with the vacuum interrupter being compact and the fast earthing circuit being simple and quick-acting.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a full-capacity circuit breaker for all functions, the patent applies partial action by using a vacuum interrupter that only needs to handle the secondary arc current (a few kiloamperes) rather than the full fault current, significantly reducing the required breaking capacity and device size.

Inventive Principle:

Principle #16Partial or excessive action

2Ease of manufacture

If traditional earthing devices are used, then the grounding function is provided, but the cost and operating energy are not optimized

Engineering Contradiction:

ImprovecostVSAvoidoperating energy

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent changes the operating parameters by using a vacuum interrupter with low-energy breaking capacity designed specifically for secondary arc interruption. This component requires minimal energy to break the current and is optimized for the specific operating conditions of rapid grounding, reducing both cost and energy consumption compared to traditional devices.

Inventive Principle:

Principle #35Parameter changes

3Speed

If the vacuum interrupter closes under fault current, then the earthing is rapid, but the contacts may weld due to arc

Engineering Contradiction:

Improveclosing speedVSAvoidcontact durability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The fast earthing circuit is designed to close first, establishing the grounding path before the vacuum interrupter closes. This preliminary action ensures that when the vacuum interrupter contacts close, the full fault current is already being carried by the fast earthing circuit, not the vacuum interrupter contacts, preventing welding.

Inventive Principle:

Principle #10Preliminary action

4Volume of moving object

If a compact device is used for restricted space, then the space requirement is reduced, but the breaking function becomes more difficult to optimize

Engineering Contradiction:

Improvedevice volumeVSAvoidbreaking function

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent extracts the breaking function from the fast earthing circuit and assigns it to a dedicated vacuum interrupter component. This extraction allows the breaking function to be independently optimized for compactness and low-energy operation while maintaining the rapid grounding capability of the fast earthing circuit.

Inventive Principle:

Principle #2Taking out (Extraction)

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 configuration optimizes the cost, size, and operating energy of the breaking function by allowing efficient extinction of secondary arcs with minimal energy consumption and preventing contact welding during fault current closure, ensuring reliable arc extinction and dielectric strength.

Implementation Method 1

a vacuum interrupter (2) of medium voltage connected in series between the fast earthing circuit (1) and the earth

Methodology Applied

Scientific EffectVacuum dielectric isolation: Vacuum

Implementation Method 2

the vacuum interrupter in series with the fast earthing circuit performs the function of interrupting the secondary arc current

Methodology Applied

Scientific EffectArc extinction in vacuum: Electric Arc

Data Source

PatentEP3076420B1Quick earth connection with breaking capacity for a station under a metal shell

Publication Date: 2017.10.04 GENERAL ELECTRIC TECH GMBH

Figure 1~2
Figure 3~6

AI summary

Fast earthing device with breaking capacity, for an electrical substation in a metal enclosure (8), the device comprising a fast earthing circuit (1, 5) of a conductor (7) of the electrical substation, characterized in that it further comprises - a vacuum switch (2) connected in series between the fast earthing circuit and earth, and - an operating member (3) adapted to actuate the fast earthing circuit and the vacuum switch.