Subsea Vacuum Interrupter Fail-Safe Mechanism
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Solution Overview
Problem
Existing subsea vacuum interrupters fail to maintain the open state during pressure increases, leading to potential implosion and equipment damage when subjected to hydrostatic pressure conditions.
Innovation Solution
A subsea pressure vessel with a vacuum interrupter and a movement counteracting arrangement, comprising a first and second counteracting member, which applies a force to maintain the movable terminal in the open state even when the interior pressure increases, preventing the terminal from moving to the closed state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the movable terminal is allowed to move freely between open and closed states, then the vacuum interrupter can operate normally for circuit protection, but the open state cannot be maintained during pressure increases leading to potential implosion
Solution Approach 1:
The movement counteracting arrangement applies a counteracting force in advance to prevent the movable terminal from moving to the closed state during pressure increases. This preliminary anti-action ensures the open state is maintained even when pressure differential tries to force the terminal closed, preventing implosion before it can occur.
Solution Approach 2:
The movement counteracting arrangement acts as a mechanical counterweight or counteracting force mechanism that balances the pressure differential force. When pressure increases create a force trying to move the terminal to the closed state, the counteracting arrangement provides an opposing force to maintain equilibrium and preserve the open state.
2Ease of manufacture
If standard electric/electronic components are used at atmospheric pressure, then component availability is improved, but thick walls are needed to withstand pressure difference making equipment heavy and costly
Solution Approach 1:
The vacuum interrupter is extracted from the atmospheric pressure environment and placed within a sealed enclosure that maintains vacuum. This allows standard components to operate in their optimal atmospheric condition while the pressure vessel only needs to withstand the external hydrostatic pressure, not the pressure differential, significantly reducing wall thickness and weight requirements.
3Weight of stationary object
If equipment is pressurized to hydrostatic pressure level, then no thick walls are needed for enclosure, but all components must be free of gas inclusions and compressible voids otherwise they implode
Solution Approach 1:
The system is segmented into two distinct pressure zones: the external pressure vessel operates at hydrostatic pressure with thin walls, while the internal vacuum interrupter enclosure maintains atmospheric pressure. This segmentation allows standard components to operate in their native atmospheric environment within the vacuum interrupter, eliminating the need for specialized pressure-resistant components while still achieving the weight reduction benefit of hydrostatic pressure operation externally.
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
Ensures a fail-safe operation of the vacuum interrupter by maintaining the open state during pressure increases below the critical pressure that would cause implosion, thereby protecting the equipment from damage.
Implementation Method 1
The fixed contact and movable contact are arranged within an enclosure which is subject to very low pressure, thus essentially defining a vacuum
Implementation Method 2
when the movable terminal is in the open state and the interior of the subsea pressure vessel is subjected to a pressure increase compared to a normal operating pressure
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The present disclosure relates to a subsea pressure vessel (1). The subsea pressure vessel (1) comprises a housing (3) arranged to maintain a pressure within an interior of the subsea pressure vessel (1) which differs from ambient pressure, a vacuum interrupter (5) arranged within the housing (3), which vacuum interrupter (5) has an enclosure (7) for maintaining a vacuum within the vacuum interrupter (5), and which vacuum interrupter (5) has a fixed terminal (9) with a fixed contact (9a) and a movable terminal (11) with a movable contact (11a), wherein the movable terminal (11) is operable between an open state in which the fixed contact (9a) and the movable contact (11a) are electrically separated and a closed state in which the fixed contact (9a) and the movable contact (11a) are electrically connected, and a movement counteracting arrangement (14) comprising a first counteracting member (15) arranged to move concurrently with the movable terminal (11) between the first state and the second state, and a second counteracting member (17) arranged to apply a counteracting force to the first counteracting member (15) when the movable terminal (11) is in the open state and the interior of the subsea pressure vessel (1) is subjected to a pressure increase compared to a normal operating pressure in the subsea pressure vessel (1) to counteract movement of the movable terminal (11) from the open state to the closed state. A subsea unit comprising a subsea pressure vessel (1) is also presented herein.