Tap Changer Contact System Rolling Wheel Wear Reduction
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Solution Overview
Problem
Existing tap changer systems experience wear issues at the ends of fixed contacts during the transition of movable contacts, leading to potential faults and reduced system reliability due to line contact and over-determination in previous designs.
Innovation Solution
A contact system with a rotatable wheel means that rolls against an abutment surface during the transition from a non-contact to a contact position, ensuring a singular rolling contact that reduces wear and simplifies the system by avoiding line contact and over-determination, with the wheel arrangement on either the movable or fixed contact part optimizing the contact surfaces for reduced wear and precise cooperation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the movable contact directly contacts the fixed contact during transition, then the contact system is simple in structure, but wear occurs at the ends of the fixed contact leading to potential faults
Solution Approach 1:
A wheel means is introduced as an intermediary element between the movable contact and the fixed contact. The wheel means rolls against the fixed contact during the entering phase, preventing direct sliding contact between the movable contact and fixed contact ends, thereby reducing wear and improving reliability while maintaining relatively simple system structure
Solution Approach 2:
The wheel means employs a curved rolling surface that contacts the fixed contact at a point or small area rather than a line. This curvature transformation converts the harmful line contact into a rolling point contact, significantly reducing wear at the fixed contact ends while maintaining structural simplicity
2Reliability
If a roller contact system is used with cam surfaces on each side, then wear at contact ends is avoided, but the system becomes over-determined and complicated
Solution Approach 1:
The invention extracts and eliminates the unnecessary cam surfaces from the contact system. Instead of using cam surfaces on each side of the fixed contact to guide the roller, the wheel means is designed to roll directly against the fixed contact during the entering phase, removing the over-determination caused by multiple cam surfaces while maintaining contact endurance through the rolling mechanism
Solution Approach 2:
Instead of using cam surfaces to lift and guide the roller contact, the invention inverts the approach by having the wheel means naturally roll against the fixed contact during the entering phase through its own rotational motion. This inversion eliminates the need for complex cam guidance while achieving the same wear-reduction effect
3Device complexity
If line contact is used between movable and fixed contacts, then the contact system is simple, but wear occurs and spring force must be transversally directed requiring cam surfaces
Solution Approach 1:
The wheel means introduces a curved rolling surface that creates point or small area contact instead of line contact between the movable and fixed contacts. This curvature transformation reduces contact stress and wear while allowing the spring force to act axially rather than transversally, eliminating the need for cam surfaces
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 effectively minimizes mechanical and electrical wear, increasing the lifespan of the contact system and reducing the risk of faults by ensuring a point or area contact rather than line contact, thus enhancing the reliability and accuracy of the tap changer operation.
Implementation Method 1
a wheel means separate from and rotatable relative to its contact surface and arranged to roll against an abutment surface of the other contact part during an entering phase of the movement from the electrical non-contacting position to the electrical contacting position
Data Source
AI summary
The invention relates to a contact system for a tap changer. The system includes a fixed contact part (1) having a first contact surface (4), and a movable contact part (2) having a second contact surface. The movable contact part (1) is movable from an electrical non-contact position to an electrical contact position and vice versa. The direction of movement is substantially parallel to the first contact surface (4). Force applying means (F) is arranged to urge said contact surfaces towards each other. According to the invention one of said contact parts includes a wheel means (3) arranged to roll against an abutment surface (6,) of the other contact part during an entering phase of the movement from the electrical non-contact position to the electrical contact position. The rolling contact is a sole and singular contact between the contact parts (1, 2,) during the entering phase