Rotary-Shaft Tap Changer for Arc-Free Load Transfer
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Solution Overview
Problem
Existing no-arc on-load tap changers are not suitable for oil-immersed transformers and have complex operation structures due to unsynchronized rotary shafts and lack of coordination control mechanisms, leading to issues with arc formation during switching processes.
Innovation Solution
A no-arc on-load tap changer design featuring rotary-shaft-type main and change-over switches with thyristor auxiliary modules, where dynamic contacts on a rotary shaft connect with static contacts to transfer load current without interruption, using a mechanical linkage mechanism for controlled breaking and closing, and thyristor auxiliary modules with RC series circuits to manage switching sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an on-load tap changer uses a conventional arc extinction method with fixed contacts and magnetic blowout coils, then the tap changer can operate under load, but it generates significant arc radiation that requires complex shielding and increases device complexity
Solution Approach 1:
The patent extracts the arc generation function from the traditional fixed contact structure by introducing movable contacts that can be dynamically positioned. The arc is confined to a dedicated extinguishing chamber rather than being allowed to radiate freely, thereby eliminating the need for complex external shielding structures while maintaining on-load switching capability.
Solution Approach 2:
The patent introduces an intermediary arc extinguishing chamber between the switching contacts and the external environment. This chamber acts as a mediator that contains and extinguishes the arc through controlled oil immersion and magnetic field action, preventing direct arc radiation to surrounding components and eliminating the need for extensive shielding.
2Object-affected harmful factors
If the tap changer uses movable contacts with arc extinguishing chambers, then arc radiation is reduced, but the switching process becomes more complex involving multiple contact movements
Solution Approach 1:
The switching process is segmented into distinct phases: pre-connection phase where movable contacts approach fixed contacts, connection phase where parallel conduction begins, and post-connection phase where movable contacts complete the transition. This segmentation allows arc extinction to occur in a controlled manner within dedicated chambers, reducing radiation while managing complexity through structured sequencing.
Solution Approach 2:
The patent employs preliminary action by establishing parallel conduction paths before fully transferring the load current. Movable contacts are positioned to create temporary parallel paths with fixed contacts, allowing the arc to be extinguished in a controlled environment before the switching is complete, thereby reducing harmful radiation while preparing the system for the next switching phase.
3Reliability
If the switching mechanism uses multiple movable contacts and parallel conduction, then switching reliability is improved, but the number of moving parts increases
Solution Approach 1:
The patent merges the functions of multiple movable contacts into a coordinated system where they work together to establish parallel conduction paths. Rather than treating each contact as an independent component, they are integrated into a unified switching mechanism that shares common actuation and control, thereby improving reliability through redundancy while limiting the increase in moving parts through functional integration.
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 enables smooth, arc-free switching in oil-immersed transformers with simplified operation, reduced switching time, lower failure rates, and cost-effectiveness by synchronizing rotary shafts and using a mechanical linkage mechanism for precise control.
Implementation Method 1
Each fixed contact has an arc extinguishing chamber provided therefor, and each movable contact has an arc extinguishing chamber provided therefor
Data Source
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AI summary
The present invention provides a no-arc on-load tap changer, a switching control method and electrical equipment, comprising at least two main switches, two change-over switches and two thyristor auxiliary modules; the two thyristor auxiliary modules are connected in parallel with originally-closed main switch or to-be-closed main switch according to required time sequence during switching of main switch; the main switches and change-over switches are rotary-shaft-type switches, dynamic contacts of main switches and change-over switches are arranged on rotary shaft, static contacts of corresponding main switches and change-over switches are connected to corresponding transformer taps, and dynamic contacts are connected with coaxial static contacts during rotating along with the rotary shaft; all switches are controlled to be broken/closed according to the preset time sequence, realizing transfer of load current from the originally-closed main switch to the to-be-closed main switch without interruption, and no arc in breaking/closing processes.