Automatic Transfer Switch Bus Impedance for Current Balancing
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Solution Overview
Problem
Automatic transfer switches (ATS) face issues with unbalanced current distribution due to the 'skin effect,' leading to increased thermal effects and early de-rating, particularly in outer conductors and cassettes, which can result in overheating and reduced lifespan.
Innovation Solution
The implementation of laminated steel on outer bus conductors and cassettes to increase impedance, rebalancing current flow and reducing thermal effects by using laminations of electric steel, cuts or slits in conductors, or altering conductor configurations to achieve a more even current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ATS configuration is used without additional impedance elements, then the device structure remains simple, but unbalanced current distribution occurs due to skin effect causing outer conductors to carry excessive current
Solution Approach 1:
The patent applies local quality by adding impedance elements specifically to outer bus conductors and contact cassettes where the skin effect causes excessive current concentration. This localized modification creates different electrical characteristics in different parts of the system, with outer conductors having higher impedance to reduce their current carrying capacity and achieve more balanced current distribution across all conductors.
2Temperature
If outer bus conductors and contact cassettes are used in conventional configuration, then the ATS can operate, but thermal effects increase due to unbalanced current distribution leading to overheating
Solution Approach 1:
The patent implements preliminary anti-action by pre-installing impedance elements on outer conductors before operation to counteract the skin effect. This preventive measure redistributes current flow to prevent excessive heating before it occurs, thereby reducing thermal effects and preventing potential overheating issues that would compromise ATS operation.
3Reliability
If steel laminations are added to outer bus conductors and contact cassettes to increase impedance, then current distribution is rebalanced, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the electrical impedance parameter of outer bus conductors and contact cassettes through the addition of steel laminations. This changes the electrical characteristics of specific components to alter current distribution patterns, transforming the system from one with unbalanced current flow to one with balanced current distribution across all conductors.
4Power
If conventional conductor configuration is used, then the ATS structure remains simple, but current carrying capability is limited due to thermal constraints on outer conductors
Solution Approach 1:
The patent applies local quality by differentiating the electrical characteristics of outer conductors from inner conductors through the addition of impedance elements. This allows the system to optimize overall current carrying capability by preventing thermal bottlenecks at outer conductors, enabling the ATS to handle higher total current loads without compromising the thermal integrity of any individual conductor.
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 approach effectively rebalances current distribution, reduces thermal issues, and enhances the lifespan of ATS components by up to 12.2°C temperature reduction, thereby improving reliability and compliance with electrical standards.
Implementation Method 1
Certain configurations may subject to the so-called 'skin effect,' in which alternating current tends to primarily flow through outer layers of conductors of the ATS
Implementation Method 2
Electromagnetic 'skin effect' cross coupling in between conductors and cassettes within each phase of such a configuration may lead to an unbalanced current distribution
Implementation Method 3
parasitic inductive and/or resistive heat losses may increase heat in the system, so as to induce temperature increases in the ATS
Data Source
AI summary
An automatic transfer switch includes a first phase switch component having a first plurality of cassettes, and at least one outer bus component disposed at an outer side of the first phase switch component. The automatic transfer switch additionally includes a first plate which is disposed on the outer side of the first phase switch component at a terminal end of the first phase switch component. The first plate is structured to increase impedance on an outer bus component of the first phase switch component to rebalance current along the first phase switch component.