Electricity Meter Contact Arrangement Magnetic Latching
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Solution Overview
Problem
Conventional electrical contactors in electricity meters face challenges with magnetic forces separating contacts during high current overload conditions and wear issues over time, leading to inconsistent closure and increased resistance, which can result in failure.
Innovation Solution
The electrical contactor design features a fixed contact with a center leg and opposing arms, and movable contacts with blades that create opposing magnetic fields to reinforce contact closure, combined with a magnetic latching actuator using cam channels and permanent magnets to ensure consistent force and movement without end stops, compensating for wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contacts are arranged with direct current flow through fixed and movable contacts opposite each other, then the magnetic forces may urge the contacts to separate during overload conditions, but this arrangement is necessary for current flow through the bus bar
Solution Approach 1:
The patent applies the counterweight principle by positioning the center leg of the fixed contact between the movable contact blades. The current flowing through the center leg creates a magnetic field that generates an attractive force opposing the repulsive magnetic force between the parallel blades. This counteracting magnetic force prevents contact separation during high current conditions, directly resolving the technical contradiction between maintaining contact closure stability and managing magnetic separation force.
2Reliability
If a compliant member is used between the actuator and moving contacts to overcome wear, then the contact wear is reduced, but the contact becomes vulnerable to bounce, inconsistent closure force or flexing of the bus bar under high current
Solution Approach 1:
The patent extracts and eliminates the compliant member from the actuator assembly. By directly coupling the actuator to the movable contact blades without intermediate compliant elements, the design removes the source of inconsistent closure force and bounce while maintaining wear resistance through the magnetic field reinforcement mechanism. The actuator's direct action on the contact blades ensures stable and consistent closure force.
Solution Approach 2:
The patent replaces the mechanical compliance system with a magnetic field-based force reinforcement system. Instead of using elastic deformation or compliant mechanical elements to manage wear and force distribution, the invention uses the magnetic field generated by the center leg current to provide consistent contact pressure and reinforcement during closure, eliminating the need for mechanical compliance while maintaining reliability.
3Reliability
If the actuator must hold the contact in the closed position during arduous overload current conditions, then the contactor survives testing conditions, but the actuator itself must be designed to withstand extreme magnetic forces
Solution Approach 1:
The patent converts the harmful magnetic repulsive force between the parallel blades into a beneficial force by strategically positioning the center leg. The current through the center leg generates a magnetic field that creates an attractive force on the movable blades, pulling them together and reinforcing contact closure. This transforms the potentially harmful magnetic effect into a force that actively maintains contact stability during overload conditions, helping the actuator survive extreme testing conditions.
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 configuration maintains contact integrity during high current and short circuit conditions, reduces wear-related failures, and provides a consistent latching force, ensuring reliable operation and extended lifespan.
Implementation Method 1
the direction of current flow creates opposing magnetic forces that urge the first and second blades outward away from the center leg of the fixed contacts
Implementation Method 2
the magnetic force attempting to separate the contacts may be approximately 1 Newton. During overload test conditions, as many as several hundred Newtons may be acting to separate the contacts
Implementation Method 3
magnetic latching actuator using cam channels and permanent magnets to ensure consistent force and movement without end stops, compensating for wear
Data Source
Figure 1~2
Figure 3
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AI summary
At least one electrical contactor is provided that includes a fixed contact and a movable contact. The fixed contact includes a center leg (36) and first and second arms (42,44) that extend in opposite directions from the center leg. The movable contact associated with each fixed contact includes first and second blades (62, 64) positioned on opposite sides of the center leg. The first and second blades extend parallel to the center leg of the fixed contact such that when current flows through the electrical contactor, the current flow creates a force to push the first and second blades into the first and second arms of the fixed contact. The electrical contactor includes an actuating arrangement having a pair of cam members. The movement of the cam members causes pegs (70) on each of the first and second blades to travel within the cam channel (102, 100), thus opening and closing the contactor arrangement.