Selective Tertiary Winding Layout for Lower Short-Circuit Current
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Solution Overview
Problem
Transformers with tertiary voltage systems face high costs and risks of high short-circuit currents due to the need for multiple wound limbs, which exacerbate the drawbacks of low power requirements and large winding sizes.
Innovation Solution
A single-phase transformer design with multiple wound limbs, where only one or more limbs have a tertiary winding, reducing the number of windings and thus decreasing manufacturing, transport, and maintenance costs, while also lowering short-circuit currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tertiary winding is added to all wound limbs in a transformer, then the transformer can provide tertiary voltage system functions (fault current redistribution, neutral point stabilization, auxiliary load supply), but the manufacturing cost and transport cost increase due to larger winding size
Solution Approach 1:
The patent extracts the tertiary winding from only some of the wound limbs rather than including it on all limbs. Specifically, the transformer has N wound limbs where only M limbs (with M < N) carry tertiary windings. This selective extraction maintains the essential tertiary voltage system functions while reducing the total amount of winding material and manufacturing complexity, thereby lowering costs.
Solution Approach 2:
The patent applies local quality by making different parts of the transformer structure have different configurations. Some wound limbs have tertiary windings while others do not. This non-uniform distribution optimizes the transformer design by providing tertiary functions only where needed, rather than uniformly across all limbs, thus reducing overall complexity and cost.
2Reliability
If a tertiary winding is added to all wound limbs in a transformer, then the transformer can provide tertiary voltage system functions, but the short-circuit current delivered to connected equipment increases excessively
Solution Approach 1:
The patent extracts the tertiary winding from only M out of N wound limbs, thereby reducing the total capacity for delivering short-circuit current. By having fewer limbs with tertiary windings, the maximum possible short-circuit current that can be delivered to connected equipment is reduced, mitigating the harmful effect while preserving essential tertiary functions.
3Power
If multiple wound limbs are used in a high power transformer, then the transformer can meet power rating requirements, but the drawbacks of tertiary voltage systems (high costs and high short-circuit currents) are exacerbated
Solution Approach 1:
The patent applies local quality by creating heterogeneity in the wound limbs structure. Out of N wound limbs required for high power rating, only M limbs are equipped with tertiary windings. This selective configuration allows the transformer to maintain high power capability through multiple limbs while avoiding the complexity and costs associated with having tertiary windings on all limbs.
Solution Approach 2:
The patent segments the transformer's wound limbs into two functional groups: M limbs with tertiary windings and (N-M) limbs without tertiary windings. This segmentation allows the high power rating to be achieved through the total number of limbs N, while the tertiary function is provided only by the subset M, reducing overall device complexity.
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 reduces short-circuit currents by up to half, leading to cost savings and improved operational efficiency by omitting tertiary windings on all but one or more limbs, thereby reducing manufacturing and transport costs and enhancing system reliability.
Implementation Method 1
A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits
Data Source
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AI summary
A transformer (200) comprising a core (201), such as, for example, a single-phase core, that comprises a plurality of wound limbs (205a, 205b), primary and secondary concentric windings (202, 204, 212, 214) formed on each limb of the plurality of wound limbs (205a, 205b), and at least one tertiary concentric winding (206) formed on fewer than all limbs of the plurality of wound limbs.