Cable Box Current Measurement Without Oil-Oil Bushings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric devices with oil-oil bushings are heavy, large, and limited in positioning, making them unsuitable for offshore and urban applications, and restrict current transformer placement, which is essential for accurate current measurement.
Innovation Solution
An electric device with a tank and cable box filled with an insulating liquid, featuring a current measuring device located adjacent to a grounded, electrically conductive shield within the cable box, allowing flexible positioning and eliminating the need for an oil-oil bushing, thereby reducing size and weight, and enabling accurate current measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an oil-oil bushing is used to connect the power cable to the tank, then the current measurement can be performed, but the device becomes heavy and large
Solution Approach 1:
The current transformer is extracted from the traditional location inside the tank and positioned outside in a cable box. This separation eliminates the need for heavy oil-oil bushings while maintaining current measurement capability through magnetic coupling or direct access to the conductor in the cable box.
Solution Approach 2:
The device is segmented into two separate compartments: the tank containing the functional part and the cable box containing the current transformer. This segmentation allows independent optimization of each component, enabling the current transformer to be lightweight while the tank maintains its structural integrity.
2Measurement precision
If an oil-oil bushing is used for current measurement, then the measurement function is achieved, but the device size increases
Solution Approach 1:
The current transformer is extracted from the tank interior and placed in an external cable box, reducing the area occupied within the tank and allowing more compact overall device design while maintaining measurement functionality.
3Measurement precision
If the current transformer is located inside the tank, then the measurement is possible, but the positioning is restricted
Solution Approach 1:
Dividing the device into tank and cable box segments allows the current transformer to be positioned flexibly in the cable box without being constrained by tank geometry, enabling adaptation to different installation configurations and application requirements.
4Object-affected harmful factors
If a grounded shield is introduced around the electric connection system, then electromagnetic shielding is improved, but the device complexity increases
Solution Approach 1:
A grounded shield is introduced as an intermediary element between the electric connection system and the current transformer. This shield acts as a mediator that blocks electromagnetic interference while maintaining electrical isolation, protecting the measurement function without requiring fundamental redesign of the device architecture.
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 allows for a compact, lightweight design suitable for offshore and urban applications, with flexible current measurement positioning and improved temperature tolerance, enabling higher power handling and accurate current monitoring.
Implementation Method 1
The grounded shield provides a shielding from the electric field in the cable box and, thus, ensures the correct functionality of the current measuring device
Implementation Method 2
The tank and the cable box are filled with an insulating liquid
Data Source
AI summary
An electric device includes a tank and a cable box connected to the tank, the tank and the cable box being filled with an insulating liquid electric connection system for connecting a power cable through the cable box to the tank and a current measuring device for measuring electric current in the electric connection system, wherein the current measuring device is located adjacent to a housing of the cable box.