Transformer Cooling System with Rising Section
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Solution Overview
Problem
Electrical devices, such as transformers, face significant temperature fluctuations due to changes in load, leading to volume changes in insulating liquids and pressure fluctuations, which require large expansion tanks and increase dehumidification costs, especially in hermetically sealed systems.
Innovation Solution
A passive temperature-dependent cooling system with a rising section and branches that adjusts the filling level of insulating liquid based on thermal expansion coefficients, increasing the cooling surface area as temperature rises, thereby acting as both a cooling system and expansion tank, potentially eliminating the need for separate expansion tanks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large expansion tank is provided to absorb volume changes of insulating liquid at high temperatures, then the transformer can handle large temperature fluctuations, but the device complexity and space requirements increase
Solution Approach 1:
The patent combines the expansion tank function with the cooling system by integrating the rising section into the existing cooling circuit. The cooling system's liquid pathway serves dual purposes: cooling the transformer and accommodating thermal expansion of the insulating liquid, thereby eliminating the need for a separate expansion tank.
Solution Approach 2:
The cooling system is designed to perform multiple functions simultaneously: it cools the transformer by circulating insulating liquid through cooling elements, and it acts as an expansion tank by providing a reservoir (rising section) that accommodates volume changes of the insulating liquid due to temperature fluctuations.
2Reliability
If hermetically sealed transformers are used to prevent moisture ingress, then reliability improves, but pressure fluctuations occur due to temperature changes
Solution Approach 1:
The rising section acts as a buffer or intermediary that absorbs the pressure fluctuations caused by thermal expansion and contraction of the insulating liquid. By providing a reservoir space, it decouples the pressure changes from the hermetic seal, maintaining both sealing integrity and pressure stability.
3Temperature
If the cooling surface area is increased to improve cooling efficiency, then temperature control improves, but the device complexity and space requirements increase
Solution Approach 1:
The cooling system is designed with dynamic characteristics where the insulating liquid flow through the cooling elements is driven by natural convection and temperature-induced density differences. The system automatically adjusts the cooling capacity based on the temperature gradient between the transformer and the rising section, providing adaptive cooling without complex control mechanisms.
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 effectively limits temperature fluctuations, provides cost-effective and reliable cooling, improves cold-starting behavior, and reduces the need for large expansion tanks, while maintaining hermetic sealing and controlling pressure fluctuations.
Implementation Method 1
the volume of the rising section is selected depending on a coefficient of thermal expansion of the insulating liquid such that the filling level reaches a different number of rising branches at prespecified temperatures
Implementation Method 2
heated insulating liquid which rises upward can flow from the rising section into the cooling element
Data Source
AI summary
An electric device has a housing and an active part in the housing that can be supplied with a high voltage and that generates heat when operated. The housing is filled with an insulating liquid for cooling. A cooling system for cooling the insulating liquid has at least one cooling element which is connected to the external atmosphere in a heat-conductive manner and via which the insulating liquid is conducted. Temperature fluctuations of the electric device are limited or even prevented in an inexpensive manner. The cooling system has a rising section which is connected to the housing, is provided with rising branches, and is connected to a cooling element at each rising branch. The volume of the rising section is selected on the basis of a thermal expansion coefficient of the insulating liquid such that the fill state reaches a different number of rising branches at specific temperatures.