Adjustable Iron Core Choke Coil Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional plunger core coils used for ground fault suppression in electrical power distribution networks generate significant adjustment noise due to the poor lubricating properties of transformer oil, leading to acoustic environmental pollution.
Innovation Solution
A choke coil with an adjustable iron core and a trapezoidal thread drive is designed, where the trapezoidal thread spindle is surrounded by a cover, such as bellows or a telescopic tube, to separate the lubricating fluid from the transformer oil, allowing for optimized lubrication and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transformer oil is used for lubrication in the trapezoidal thread drive, then cooling and insulation functions are maintained, but adjustment noise increases due to poor lubricating properties
Solution Approach 1:
The patent divides the oil system into two separate compartments: one containing transformer oil for cooling and insulation, and another containing lubricating oil for the trapezoidal thread drive. This segmentation allows each oil type to perform its specialized function without interference, resolving the contradiction between noise reduction and functional requirements.
Solution Approach 2:
A common wall separates the two oil compartments, acting as an intermediary barrier that prevents mixing while allowing thermal energy transfer. This mediator enables the system to maintain both cooling functionality and low-noise operation by keeping the lubricating oil isolated from the transformer oil.
2Device complexity
If a single oil system is used for both cooling and lubrication, then device complexity is reduced, but lubricating properties are insufficient leading to high adjustment noise
Solution Approach 1:
The oil system is segmented into two functionally independent compartments: a transformer oil compartment for cooling and insulation, and a lubricating oil compartment for the trapezoidal thread drive. This segmentation resolves the contradiction by allowing specialized lubrication without significantly increasing overall system complexity.
Solution Approach 2:
Different oil qualities are applied to different locations based on functional requirements: transformer oil with excellent insulating and cooling properties in the main tank, and lubricating oil with optimized viscosity and lubricating characteristics in the thread drive compartment. This local differentiation resolves the contradiction between simplicity and operational performance.
3Temperature
If transformer oil is used throughout the coil, then cooling and insulation are optimized, but the lubricating properties cause loud adjustment noise during core movement
Solution Approach 1:
The patent segments the fluid system so that transformer oil handles thermal management (cooling and insulation) while a separate lubricating oil handles friction reduction in the mechanical drive. This segmentation allows each fluid to be optimized for its specific function, resolving the contradiction between cooling efficiency and noise generation.
Solution Approach 2:
The common wall acts as a thermal intermediary, allowing heat transfer from the transformer oil side to the lubricating oil side, thereby maintaining cooling efficiency while keeping the lubricating oil isolated to prevent noise-generating mixing and maintain its lubricating properties.
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 significantly reduces adjustment noise and minimizes acoustic pollution by using a lubricating oil with improved properties, while maintaining the cooling and insulating benefits of transformer oil.
Implementation Method 1
By rotating the trapezoidal thread spindle protruding into the iron core, the trapezoidal thread nut and thus also the core move along the trapezoidal thread spindle. This converts the rotary movement of the drive motor into a longitudinal movement of the core in the air gap of the coil and thus changes the inductance of the coil.
Implementation Method 2
The invention is based on the finding that the adjustment noise is mainly due to the poor lubricating properties of the transformer oil. The part of the trapezoidal thread spindle running outside of the iron core is now surrounded by a cover, which can consist, for example, of bellows or a telescopic tube. The sheath separates a lubricating fluid surrounding the trapezoidal thread spindle from the transformer oil in the choke coil.
Implementation Method 3
Transformer oil is a highly refined mineral oil or a thin liquid silicone oil or a natural ester or a synthetic ester that is stable at high temperatures and has good electrical insulating properties.
Implementation Method 4
Oil-filled shunt reactors are generally designed with so-called ONAN cooling, i.e. with natural convection of the ambient air, or with high power also with ONAF cooling, in which the air flow is forced by a fan.
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a choke coil with an adjustable iron core (EK) and trapezoidal thread drive, wherein the iron core is connected to a trapezoidal thread nut (TGM) which is arranged on a trapezoidal thread spindle (TGS) projecting into the iron core (EK), wherein the part of the trapezoidal thread spindle (TGS) extending outside the iron core (EK) is enclosed by a casing (FB,TR) which separates a lubricating fluid (SV) surrounding the trapezoidal thread spindle (TGS) from the transformer oil (OE) of the choke coil. This results in a significant reduction of adjustment noise and a decrease in the acoustic environment.