On-load tap changer centering and kerosene drain design

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Solution Overview

Problem

Existing on-load tap changers require complex and costly assembly and disassembly processes for the diverter switch insert and oil suction tube, often necessitating special tools to avoid damage to actuating elements and switching segments.

Innovation Solution

The on-load tap changer design features a centrally arranged oil suction tube and a kerosene drain plug, with a bearing ring loaded by an elastic element to facilitate easy alignment and disassembly, allowing the switching tube and oil suction tube to be centered and removed without special tools, and a kerosene drain plug that can be actuated simply by rotating the oil suction pipe.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the switching tube and oil suction tube are installed in the oil compartment, then the on-load tap changer can function properly, but the assembly and disassembly processes become complex and costly requiring special tools

Engineering Contradiction:
Improvefunctional operationVSAvoidassembly process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the on-load tap changer into modular components: a diverter switch insert (containing the switching tube with switching segments) and a separate oil suction tube assembly. This segmentation allows each module to be independently assembled, inspected, and replaced without requiring complex special tools for the entire device.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The oil suction tube is extracted as a separate, easily removable component from the oil compartment. The patent provides specific provisions (opening in the bottom, engagement elements) that allow the oil suction tube to be taken out independently for maintenance or replacement without disassembling the entire switching mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of manufacture

If standard assembly methods are used for the switching tube and oil suction tube, then manufacturing is simpler, but damage to actuating elements and switching segments occurs during assembly and disassembly

Engineering Contradiction:
Improveassembly simplicityVSAvoidcomponent integrity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent incorporates preliminary protective features into the design: guide elements and engagement provisions are pre-positioned to ensure proper alignment during assembly before the actual connection is made. The bearing ring with elastic element is pre-installed to provide cushioning and precise positioning during the insertion process, preventing damage before it can occur.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent employs a bearing ring loaded with an elastic element that provides beforehand cushioning during the assembly of the switching tube. This elastic bearing ring absorbs impact forces and provides gentle guidance, preventing damage to the switching segments and actuating elements during insertion and disassembly operations.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If the kerosene drain plug is positioned for easy access, then maintenance is simpler, but the plug becomes inaccessible when the switching tube is installed

Engineering Contradiction:
Improvemaintenance accessibilityVSAvoidspatial arrangement
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent positions the kerosene drain plug asymmetrically in the bottom of the oil compartment, specifically at a location that is radially offset from the central axis of the switching tube. This asymmetric positioning ensures that the drain plug remains accessible from the bottom even when the switching tube is installed in its operational position, allowing maintenance personnel to reach the plug without removing the switching tube.

Inventive Principle:
Principle #4Asymmetry

4Manufacturing precision

If a bearing ring with elastic element is used to center the switching tube, then alignment is improved, but the device structure becomes more complex

Engineering Contradiction:
Improvecentering accuracyVSAvoidstructure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The bearing ring with elastic element is designed to automatically center the switching tube through its own elastic deformation properties. When the switching tube is inserted, the elastic element compresses and expands to naturally guide the tube into the correct central position without requiring external alignment tools or complex adjustment mechanisms. The system self-regulates its positioning function.

Inventive Principle:
Principle #25Self-service

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 simplifies the assembly and disassembly of the on-load tap changer, reduces the risk of damage to internal components, eliminates the need for special tools, and allows for easy actuation of the kerosene drain plug, thereby reducing costs and improving operational efficiency.

Implementation Method 1

a bearing ring (53) loaded on one side and radially with an elastic element (54)

Methodology Applied
Scientific EffectElastic force: Elasticity

Data Source

PatentEP3022751B1On-load tap changer, method for installing a load transfer switch insert in the on-load tap changer, and kerosene drain screw
Publication Date: 2017.09.13 MASCHFAB REINHAUSEN GMBH
  • EP3022751B1 patent drawingFigure 1
  • EP3022751B1 patent drawingFigure 2~3
  • EP3022751B1 patent drawingFigure 4

AI summary

The invention relates to an on-load tap changer (1), comprising a load transfer switch insert (14) and an oil suction pipe (60), and to a method for installing a load transfer switch insert (14) by means of the switching tube (15) and the oil suction pipe (60). The oil suction pipe (60) is arranged centrally, and coaxially along an axis (A) of the on-load tap changer (1), within the switching tube (15). The on-load tap changer (1) has a kerosene drain screw (70), which is attached in a bottom (21) of the on-load tap changer (1) in such a way that the kerosene drain screw is arranged coaxial to the axis (C) of the oil suction pipe (60), to the axis (B) of the switching tube (15), and to the axis (A) of the on-load tap changer (1). A bearing ring (53) is acted upon on one side and radially to the axis (A) of the on-load tap changer (1) by an elastic element (54) in such a way that the switching tube (15) and the oil suction pipe, which both interact (60) with the bearing ring (53) in a form-closed manner, are centered about the axis (A) of the on-load tap changer.