Potential Transformer Isolating Device for Gas-Insulated Switchgear

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Solution Overview

Problem

The existing potential transformer isolating devices for medium and high voltage gas-insulated switchgear and control devices using dry air as the insulation medium suffer from inadequate electric field intensity and insulation distance, posing safety risks during maintenance due to the U-shaped structure and small wire spring diameter.

Innovation Solution

A potential transformer isolating device featuring a compression spring and internally threaded nut with a guide pole and catch mechanism, along with a retractable round stick design, which automatically adjusts to ensure reliable grounding and improved insulation distance by eliminating the U-shaped structure and enhancing the electric field intensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the U-shaped structure with wire spring is used for potential transformer isolating, then the device can be successfully used for medium-voltage gas switchgear with sulfur hexafluoride insulation, but the electric field intensity becomes too strong and insulation distance becomes insufficient when used with dry air as insulation medium

Engineering Contradiction:
Improveisolation functionVSAvoidelectric field intensity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the U-shaped structure from the isolating device design. By extracting this problematic component, the patent eliminates the source of strong electric field concentration while maintaining the isolation function through alternative structural arrangements that are compatible with dry air insulation medium.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the geometric parameters of the isolating device, specifically replacing the U-shaped configuration with a different structural form that distributes the electric field more evenly. This parameter change reduces electric field intensity at critical points while preserving the isolating functionality for dry air-insulated switchgear.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the U-shaped structure is used at high and low voltage positions, then the blade arm can clip the end spring to achieve conduction or grounding, but the insulation distance is reduced and safety threats to maintenance personnel increase

Engineering Contradiction:
Improveconduction or grounding functionVSAvoidinsulation distance
Core Design Contradiction:
Ease of operationVSLength of stationary object

Solution Approach 1:

The patent extracts and eliminates the U-shaped structure that compromises insulation distance. The new design maintains the conduction and grounding functions through alternative mechanical arrangements that do not require the U-shaped configuration, thereby preserving safety clearance and insulation distance.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a blade arm mechanism as an intermediary component that achieves conduction or grounding without requiring the U-shaped structure. This mediator maintains electrical connectivity or grounding capability while preserving adequate insulation distance, thus protecting maintenance personnel.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Volume of moving object

If the wire spring with small diameter is used, then the isolating device can be compact, but the field intensity becomes extremely strong which is disadvantageous for insulation

Engineering Contradiction:
Improvedevice compactnessVSAvoidfield intensity
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent changes the geometric parameters of the spring component, increasing the wire diameter to reduce electric field intensity. This parameter modification balances the compactness requirement with insulation requirements, creating a design that is both space-efficient and electrically safe for dry air insulation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent may employ composite material structures or optimized material selection for the spring component that allows for larger dimensions without proportionally increasing device volume. This enables maintaining compactness while using thicker wire to reduce field intensity.

Inventive Principle:
Principle #40Composite materials

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

The solution provides superior electric field intensity and increased insulation distance, ensuring safe and reliable operation of medium-voltage gas-insulated switchgear and control devices, enhancing maintenance safety and insulation performance.

Implementation Method 1

a first spring, configured to store and release energy to drive the isolating device to move between a first position and a second position

Methodology Applied
Scientific EffectElastic potential energy: Elasticity

Implementation Method 2

a guide pole with a catch mechanism

Methodology Applied
Scientific EffectMechanical guidance:

Implementation Method 3

The solution provides superior electric field intensity and increased insulation distance

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Data Source

PatentEP3288050B1Potential transformer isolating device and gas-insulated switchgear
Publication Date: 2021.11.10 ABB (SCHWEIZ) AG
  • EP3288050B1 patent drawingFigure 1A~1B
  • EP3288050B1 patent drawingFigure 1C~2C
  • EP3288050B1 patent drawingFigure 2D~2F

AI summary

A potential transformer isolating device comprises a swinging rod (11,31), a guide pole(14,34), and a compression device(13,33). The guide pole (14, 34) has a guide-pole guide end (142,342) and an arc-shaped guide-pole connecting end (141,341). When the guide-pole connecting end (141,341) is under the action of the external force, the guide pole can move along the swinging rod (11, 31), and the compression device (13,33) is compressed. When the external force is removed, the guide pole (14, 34) can be reset under the action force of the compression device (13, 33). Therefore, the design of the telescopic round stick is good for improving the insulation levels of the gas insulated switchgear and the control device.