Compact On-Load Tap Changer for Uninterrupted Tap Switching
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Solution Overview
Problem
Existing on-load tap changers are not compact enough for use in small distribution transformers, necessitating a design that allows for uninterrupted switching between different winding taps.
Innovation Solution
A compact on-load tap changer design featuring a slow-moving and a fast-moving selector contact package, where the fast-moving package moves at a higher speed than the slow-moving package, utilizing a linear movement mechanism with separate motion transmissions and force store units to ensure seamless switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional on-load tap changer design is used, then switching between winding taps can be achieved, but the device dimensions are too large for small distribution transformers
Solution Approach 1:
The selector contact package is divided into multiple independent selector contacts (first, second, third selector contacts) arranged in sequence. Each selector contact can be operated independently or in coordination, allowing the switching function to be distributed across multiple smaller components rather than requiring a single large mechanism.
Solution Approach 2:
The patent employs dynamic operation where selector contacts can switch between different positions (connected to different winding taps) during transformer operation. The mechanism allows for intermediate positions and sequential switching operations, enabling uninterrupted tap changing while maintaining compact dimensions through controlled motion sequences.
2Speed
If the selector contact package moves at high speed, then switching time is reduced, but mechanical stress and wear increase
Solution Approach 1:
The switching operation is performed in periodic cycles where the selector contact package moves between discrete positions. The mechanism uses controlled periodic motion with acceleration and deceleration phases, allowing high average switching speed while limiting peak mechanical stresses through rhythmic, controlled operation rather than continuous high-speed movement.
Solution Approach 2:
The design incorporates preliminary positioning and preparation phases before the actual switching action. Selector contacts are pre-positioned and prepared for switching, with force store units pre-charged, allowing the actual contact making/breaking to occur quickly while the overall cycle manages mechanical stress through staged preparation and execution.
3Reliability
If multiple selector contacts are used to enable uninterrupted switching, then switching reliability improves, but device complexity increases
Solution Approach 1:
Multiple selector contacts (first, second, third selector contacts) are merged into a single integrated selector contact package that moves as one unit. This package combines multiple switching functions in a compact assembly, reducing the number of separate mechanisms while maintaining the reliability benefits of multiple contact points for uninterrupted switching.
Solution Approach 2:
The selector contact package serves multiple functions simultaneously: it connects to different winding taps, provides intermediate positioning, enables sequential switching operations, and maintains electrical continuity. This multi-functionality reduces the need for separate dedicated components for each function, simplifying the overall device while achieving reliable uninterrupted switching.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
In one embodiment, the on-load tap changer (1) is for a distribution transformer (10) and comprises: - a driving system (2) including a force store unit (31), - a slow-moving selector contact package (4), and - a fast-moving selector contact package (5), wherein - the driving system (2) is to move the slow-moving selector contact package (4) with a first speed and the fast-moving selector contact package (5) with a second, higher speed from a first selector contact (11) to a second selector contact (12) of the transformer (10), - the driving system (2) is to begin movement of the fast-moving selector contact package (5) later than movement of the slow-moving selector contact package (4), and - the force store unit (31) is loaded during movement of the slow-moving selector contact package (4) and is unloaded to drive movement of the fast-moving selector contact package (5) .