Auxiliary Contact Plate Layout for Open-State Contactor Detection
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Solution Overview
Problem
Existing switching devices, particularly gas-filled contactors, face challenges in reliably detecting a completely open state, as conventional monitoring methods are expensive, prone to insulation issues, or sensitive to magnetic interference, and fail to meet the IEC 60947-5-1 standard requirements for 'normally closed' detection.
Innovation Solution
A switching device design with fixed and movable contacts, auxiliary contacts, and a contact plate, housed in a gas atmosphere, uses a mechanical drive with an armature and insulating contact holder to ensure reliable detection of open and closed states, while maintaining insulation and immunity to magnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage measurement via main contacts is used for monitoring, then detection reliability is improved, but cost and complexity increase due to high-voltage cable insulation requirements
Solution Approach 1:
The monitoring function is segmented from the main power circuit by introducing separate auxiliary contacts that are electrically isolated from the high-voltage main contacts. This allows monitoring to be performed on a separate, lower-voltage circuit while maintaining detection reliability.
Solution Approach 2:
Auxiliary contacts serve as intermediaries between the main switching mechanism and the monitoring system. These contacts transfer the switching state information to the monitoring circuit without requiring direct connection to the high-voltage main contacts, thereby eliminating the need for complex high-voltage cable insulation.
2Device complexity
If microswitch with cantilever is used for monitoring, then device complexity is reduced, but insulation performance deteriorates due to placement near main contacts
Solution Approach 1:
The monitoring function is spatially segmented from the main contact area by placing auxiliary contacts in a separate location within the switching device. This physical separation eliminates the insulation problems associated with placing microswitches near the arc-generating main contacts while maintaining simple mechanical monitoring.
3Ease of manufacture
If overlapping contacts are used for monitoring, then manufacturing cost is reduced, but insulation performance deteriorates due to contact placement between main contacts
Solution Approach 1:
The auxiliary contacts are segmented from the main contact assembly and positioned in a separate spatial location. This allows simple, low-cost contact construction while maintaining adequate insulation distance from the main power contacts, avoiding the insulation problems of overlapping contact designs.
4Object-affected harmful factors
If Hall sensor is used for monitoring, then magnetic interference sensitivity is reduced, but switching behavior similarity to reed switch persists
Solution Approach 1:
Both magnetic sensing approaches (reed switch and Hall sensor) are replaced with direct mechanical auxiliary contacts that provide unequivocal switching state detection. The mechanical contact system eliminates all magnetic interference issues and provides reliable, unambiguous switching state information without the intermediate magnetic field conversions.
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 provides reliable detection of open and closed states, ensuring compliance with IEC 60947-5-1 standards, while maintaining insulation and reducing sensitivity to vibrations and mechanical shocks, suitable for use in gas-filled contactors.
Implementation Method 1
each of the spring contacts (30) comprises at least a first contact region (301) and a second contact region (302). With its first contact region (301), each of the spring contacts (30) can contact one of the auxiliary contacts (25) permanently and independently of the switching states of the switching device (100)
Implementation Method 2
The switching device can particularly preferably be designed as a gas-filled power contactor... one application of such switching devices, in particular power contactors, is the opening and disconnection of battery circuits... electric arcs that form between the contacts during switching operations under load and can cause such high temperatures at the contact surfaces that the contact surfaces are welded together
Data Source
AI summary
In an embodiment a switching device includes at least two fixed contacts and one movable contact in a switching chamber and at least two auxiliary contacts, two spring contacts and a contact plate in the switching chamber, wherein each of the spring contacts contacts one of the auxiliary contacts with a first contact region and has a second contact region, wherein the contact plate is movable together with the movable contact, and wherein the contact plate is configured to contact the second contact regions of the spring contacts in a first switching state of the switching device and is configured to be arranged at a distance from the second contact regions of the spring contacts in a second switching state.