Subsea Contactor Arrangement with Electromagnetic Contact Pressure
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Solution Overview
Problem
Conventional contactors are not suitable for subsea applications as they suffer severe damage and become inoperable when maintaining a closed state during short circuit conditions, leading to excessive heating and welding of contacts due to high currents, which is costly and technically challenging to replace.
Innovation Solution
A contactor arrangement with a conductor section connected in series between terminals, where the current direction is opposite or parallel to the movable contact, generating repelling or attractive forces to increase contact pressure, preventing blow-off and allowing operation during short circuits without arcing and maintaining functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contactor remains closed during short circuit conditions, then arcing and combustion of dielectric liquid are prevented, but excessively high currents cause blow-off force that separates contacts and reduces contact pressure
Solution Approach 1:
The patent introduces a counterbalancing force mechanism using a spring element that applies a closing force on the movable contact to counteract the blow-off force generated during short circuit conditions. This spring force maintains contact pressure between the contacts even when electromagnetic blow-off forces attempt to separate them, resolving the contradiction between preventing arcing and maintaining contact pressure.
Solution Approach 2:
The patent employs a dynamic force balance system where the spring constant and pre-compression are designed to provide adequate contact pressure during normal operation while allowing the contacts to remain closed during short circuits. The dynamic interaction between electromagnetic forces, spring forces, and friction ensures the contacts stay pressed together during fault conditions without welding.
2Reliability
If the contactor remains closed during short circuit conditions, then arcing is prevented, but excessive heating occurs due to increased resistance from reduced contact force
Solution Approach 1:
The spring element provides a counterbalancing force that maintains adequate contact pressure during short circuit conditions, preventing the reduction in contact force that would otherwise occur due to electromagnetic blow-off effects. This sustained contact pressure minimizes contact resistance and prevents excessive heating at the contact interfaces.
Solution Approach 2:
The patent converts the harmful electromagnetic blow-off force into a beneficial effect by designing the spring mechanism to be compressed during normal operation and then release this stored energy during short circuits to maintain contact pressure. The system uses the operational cycle itself to recharge the spring, which then provides the necessary force during fault conditions.
3Ease of operation
If conventional contactors are used in subsea applications, then standard switching functionality is provided, but the contactor becomes inoperable after short circuit damage requiring costly replacement
Solution Approach 1:
The patent implements protective measures in advance by incorporating the spring-loaded contact pressure maintenance system and conductor section design that prevent contact welding and damage during short circuit conditions. This beforehand cushioning against potential damage eliminates the need for costly replacement operations in subsea environments.
Solution Approach 2:
The contactor arrangement provides self-protection during short circuit conditions through the automatic action of the spring mechanism that maintains contact pressure and the conductor section geometry that distributes current. The system automatically counteracts harmful effects without external intervention, ensuring continued operability and eliminating the need for replacement.
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 contactor arrangement effectively reduces contact resistance and prevents melting by increasing contact pressure, ensuring the contactor remains operational during short circuits and can be opened quickly, minimizing arcing and maintaining reliability in dielectric liquid environments.
Implementation Method 1
a current between the first and second connection terminals via the movable contact and the conductor section results in an electromagnetic force being exerted on the movable contact
Implementation Method 2
the current through the conductor section has a direction that is substantially opposite to the direction of the current through the movable contact, so that a repelling force is generated between the movable contact and the conductor section, the arrangement being such that the repelling force increases the contact pressure
Data Source
AI summary
A contactor arrangement for operation in a dielectric liquid environment may include a first connection terminal and a second connection terminal, a contactor having a fixed contact, and a movable contact that is movable relative to the fixed contact, the contactor having an open state in which the movable contact is spaced apart from the fixed contact and a closed state in which the movable contact is in contact with the fixed contact so as to provide an electric connection through the contactor via the movable contact. The contactor arrangement may further include a conductor section.