Vacuum Arc Extinguishing Change-Over Selector for Transformer Oil Protection
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Solution Overview
Problem
Existing on-load tap-changer technologies face challenges in managing recovery voltage during voltage regulation, leading to potential arc discharges that can contaminate transformer oil and increase complexity and cost.
Innovation Solution
A change-over selector with a vacuum arc extinguishing circuit, featuring a vacuum tube connected in parallel to the main circuit, which is activated to prevent arc formation outside the vacuum tube, ensuring no potential difference exists between moving and static contacts during switching, thus containing arcs within the vacuum tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed potential resistor is mounted between the middle portion of voltage regulating coil and change-over switch leading-out terminal, then the recovery voltage is limited, but the structure becomes simple and power is wasted continuously causing transformer oil temperature increase
Solution Approach 1:
The patent replaces the fixed potential resistor with a dynamic switching mechanism using a moving contact that can be positioned at different locations (+, -, or middle position). This dynamic configuration allows the system to connect the voltage regulating winding to different potentials only when necessary during change-over operations, eliminating continuous power waste while still limiting recovery voltage effectively.
Solution Approach 2:
The patent implements periodic connection of the voltage regulating winding to reference potentials through the moving contact. The moving contact periodically touches the + or - static contacts during normal operation to equalize potential, and connects to the middle position during change-over to limit recovery voltage. This periodic action replaces continuous power consumption with intermittent, controlled connections.
2Ease of operation
If the moving contact separates from + or - static contact during polarity change-over, then the voltage regulating winding is separated from primary winding creating electrical floating state, but displacement voltage causes continuous discharging on clearance exceeding endurance
Solution Approach 1:
The patent introduces a middle position static contact as an intermediary during polarity change-over operations. When the moving contact transitions from + to - or vice versa, it first connects to the middle position, which is electrically connected to both + and - through resistors. This intermediary connection provides a reference potential that prevents displacement voltage buildup, eliminating continuous discharging while enabling smooth polarity change-over.
Solution Approach 2:
The middle position static contact creates an equipotential reference point during change-over operations. By connecting the voltage regulating winding to this middle position through the moving contact, the system equalizes potential between different windings, preventing the potential difference that causes displacement voltage and continuous discharging on clearances.
3Adaptability or versatility
If coarse or thin regulation change-over selector operates at middle position K, then coarse or thin regulation and polarity change-over are achieved, but the voltage regulating winding is separated from primary winding creating electrical floating state
Solution Approach 1:
The patent segments the voltage regulating system into coarse regulation (through polarity change-over) and thin regulation (through tap selection) functions. The middle position K enables both functions by allowing the moving contact to switch between different configurations. However, the system maintains reliability by ensuring that even during these segmented operations, the voltage regulating winding remains connected to reference potentials through the resistor network, preventing electrical floating state.
4Productivity
If dual polarity change-over principle is used with pair of static contacts and pair of moving contacts, then change-over selection without interruption is implemented, but drive mechanism and synchronization increase complexity and cost
Solution Approach 1:
The patent makes the single moving contact universal by enabling it to perform multiple functions: it can connect to + static contact for one polarity, to - static contact for opposite polarity, or to middle position for potential equalization. This multi-functional design eliminates the need for separate moving contacts and complex synchronization mechanisms required by dual polarity systems, achieving uninterrupted change-over with simpler structure.
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 solution simplifies the mechanism, prevents transformer oil contamination, reduces space and cost, and ensures reliable operation by containing arcs within the vacuum tube, thereby enhancing the reliability and efficiency of voltage regulation.
Implementation Method 1
a vacuum arc extinguishing sub-circuit including a vacuum tube is connected in parallel to the change-over selection main-circuit, the vacuum tube is opened after the moving contact is separated from the first static contact, and the vacuum tube is closed before the moving contact is electrically connected to the second static contact
Data Source
AI summary
Disclosed is a change-over selector with a vacuum arc extinguishing circuit, including a central shaft, a moving contact driven by the central shaft to rotate, and a first static contact and a second static contact circularly arranged on insulation laths of a cage body of the change-over selector, where the moving contact is driven by the central shaft to rotate to switch between the first static contact and the second static contact, the moving contact and the first and second static contacts form a change-over selection main-circuit, a vacuum arc extinguishing sub-circuit including a vacuum tube is connected in parallel to the change-over selection main-circuit, the vacuum tube is opened after the moving contact is separated from the first static contact, and the vacuum tube is closed before the moving contact is electrically connected to the second static contact.