Power Transformer Stepping Switch Single Expansion Tank
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Solution Overview
Problem
Existing solutions for compensating thermal expansion in oil-filled power transformers and tap changers require significant structural modifications and additional components, such as separate expansion tanks or nitrogen-filled systems, which increase complexity and size, while also facing issues with material durability and oxidation protection.
Innovation Solution
A single expansion tank is used to absorb the volume changes of both the transformer and tap changer oils, with the tap changer's flange connected to the transformer's oil tank via a pipeline, and an oil flow relay detects potential malfunctions, accompanied by a pressure relief valve to prevent overpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate expansion tanks are used for transformer and tap changer, then thermal expansion compensation is achieved, but device complexity and external dimensions increase significantly
Solution Approach 1:
The patent merges the expansion tank functions for both the transformer and tap changer into a single integrated expansion tank. The tap changer's flange is connected to the transformer's oil tank via a pipeline, allowing the single expansion tank to absorb volume changes from both oil systems, thereby reducing structural complexity while maintaining thermal expansion compensation capability.
Solution Approach 2:
The single expansion tank serves multiple functions: it compensates for thermal expansion of both transformer oil and tap changer oil, acts as a sealed system to prevent oxidation, and eliminates the need for separate expansion vessels. This multi-functionality reduces the overall number of components and simplifies the structural design.
2Object-affected harmful factors
If nitrogen-filled expansion tanks are used, then oxidation protection is achieved, but external dimensions and structural complexity increase by around 20%
Solution Approach 1:
The patent combines the nitrogen-filled sealed system for both transformer and tap changer into a single integrated system. The single expansion tank with nitrogen cushion protects both oil systems from oxidation simultaneously, eliminating the need for separate nitrogen-filled tanks and reducing external dimensions.
Solution Approach 2:
The expansion tank is filled with nitrogen to create an inert atmosphere that prevents oxidation of the transformer oil and tap changer oil. This inert environment protection is achieved in a single tank rather than requiring separate nitrogen-filled systems for each component.
3Object-affected harmful factors
If rubber bags or membranes are used in expansion tanks, then oxidation protection is achieved, but service life is limited to 10-15 years due to material aging
Solution Approach 1:
The patent uses a nitrogen-filled sealed system without rubber bags or membranes. The nitrogen cushion directly contacts the oil system, creating an inert atmosphere that prevents oxidation. This eliminates the rubber material aging problem and extends service life indefinitely, as there are no rubber components to deteriorate.
Solution Approach 2:
The patent avoids using rubber bags or membranes that have limited service lives (10-15 years). By replacing these short-lived rubber components with a nitrogen-filled sealed system, the solution eliminates the need for periodic replacement of aging rubber parts.
4Temperature
If expansion radiators are used, then cooling and thermal expansion compensation are achieved, but the system requires direct contact with ambient air leading to oil oxidation
Solution Approach 1:
The patent uses a nitrogen-filled sealed expansion tank system that prevents direct contact between the oil and ambient air. The nitrogen cushion creates an inert atmosphere that protects the oil from oxidation while still allowing for thermal expansion compensation and cooling capabilities.
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 solution simplifies thermal expansion compensation with minimal structural effort, enhances reliability by detecting oil flow anomalies, and limits mechanical damage through pressure regulation, while maintaining a sealed system to prevent oxidation.
Implementation Method 1
it is necessary to provide means for compensating for the thermal expansion of the oil
Implementation Method 2
the gas space of which is filled with nitrogen... the volume of which is dimensioned in such a way that the pressure conditions that arise due to the volume expansion of the oil remain within a specified, permissible range
Implementation Method 3
an impermissibly high overpressure can be automatically released to the ambient air via a valve
Implementation Method 4
a closed system can be set up in which the transformer oil has no direct contact with the outside air and therefore cannot oxidize
Data Source
Figure 1a~1b
AI summary
The abstract relates to an arrangement of an oil-filled power transformer having an oil-filled stepping switch, wherein only a single oil expansion vessel is provided, this oil expansion vessel being connected both to the oil volume of the stepping switch and also to the transformer tank, which is likewise oil-filled, via corresponding flanges.