Parallel Transfer Switch Contacts with Electromagnetic Closure

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Solution Overview

Problem

Automatic transfer switches face challenges in providing cost-effective, easy-to-assemble designs that can withstand and close on very high short circuit fault currents while allowing circuit breakers to open under appropriate circumstances, especially in high-power applications.

Innovation Solution

A movable contact assembly with longitudinally extending finger conductors and blade connectors is designed to pivot between stationary contact assemblies, employing electromagnetic forces to maintain contact closure during high fault currents, and a contact spring arrangement to ensure proper tension and reduce contact bounce.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transfer switch contacts are designed to remain closed during fault conditions using mechanical operators with toggles, then the switch can withstand fault currents, but the device complexity increases and cost increases

Engineering Contradiction:

Improvefault current withstanding capabilityVSAvoidmechanical operator complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical operator systems with electromagnetic forces generated by fault currents themselves. The electromagnetic force naturally acts to keep contacts closed during faults, eliminating the need for mechanical toggles and operators while maintaining reliability during fault conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The fault current passing through the contacts generates electromagnetic force that automatically maintains contact closure during fault conditions. The system uses the fault current itself to serve the protective function, rather than requiring external mechanical operators.

Inventive Principle:

Principle #25Self-service

2Object-affected harmful factors

If circuit breakers employ electromagnetic forces to blow contacts open, then fault current limitation is achieved, but transfer switches cannot maintain closed state during faults

Engineering Contradiction:

Improvefault current limitationVSAvoidcontact closure maintenance during faults

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

Instead of using electromagnetic force to open contacts like circuit breakers, the patent inverts the approach by allowing electromagnetic force to keep contacts closed during faults. The same physical principle is used with opposite effect - the electromagnetic force generated by fault current naturally maintains contact closure rather than forcing separation.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If transfer switches are designed for high withstand and close-on current ratings, then reliability during faults improves, but manufacturing cost and assembly complexity increase

Engineering Contradiction:

Improvewithstand and close-on current capabilityVSAvoidassembly and installation ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The contact assembly is divided into modular components - stationary contacts, movable contacts, and spring mechanisms - that can be manufactured separately and assembled systematically. This segmentation enables standardized production processes and simplifies assembly while achieving high current ratings.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

By replacing complex mechanical operator systems with electromagnetic force utilization, the patent reduces the number of mechanical parts requiring assembly. This substitution simplifies manufacturing and assembly processes while maintaining high withstand and close-on current capabilities.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 the automatic transfer switch to effectively withstand and close on high short circuit fault currents, ensuring reliable power transfer and extending the useful life of contact components while allowing circuit breakers to open appropriately.

Implementation Method 1

a contact spring arrangement to ensure proper tension and reduce contact bounce

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

designed to withstand and/or close on very high short circuit fault currents by employing electromagnetic forces to keep contacts closed

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentUS9281138B2Parallel type transfer switch contacts assemblies

Publication Date: 2016.03.08 ASCO POWER TECHNOLOGIES LP

AI summary

A movable contact assembly for use with a transfer switch, the moveable contact assembly comprising a center portion, a first conductor portion extending from the center portion, the first conductor portion comprising a first arm comprising two longitudinal extending fingers; and a second conductor portion extending from the center portion, the second conductor portion comprising a second arm comprising two longitudinally extending fingers. The moveable contact assembly may be pivoted about the center portion from a first position to a second position. In the first position, the two longitudinally extending fingers of the first conductor portion resides in a conductive state with a blade connector of a first stationary contact assembly and in the second position, the two longitudinally extending fingers of the second conductor portion resides in a conductive state with a blade connector of a second stationary contact assembly.