Earthing Switch Interlock Mechanism for Gas Insulated Substations
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Solution Overview
Problem
Gas insulated substations lack effective mechanisms to prevent unauthorized or unintended operation of earthing switches, which can lead to safety and reliability issues.
Innovation Solution
An interlock system is introduced that includes a swivel lever, rotating axle, key lock, and spring mechanism to block or free the cogwheel of the actuation mechanism, ensuring the earthing switch can only be operated within authorized and intended states by requiring a specific sequence of actions, including the use of keylocks and a rotating knob.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interlock mechanism is added to prevent unauthorized operation, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The interlock mechanism is divided into separate functional components: a swivel lever for blocking the cogwheel, a rotating axle with cam disc for actuation, a spring for maintaining blocking force, and a key lock for securing the axle. This segmentation allows each component to perform its specific function independently while maintaining overall system reliability without excessive complexity.
Solution Approach 2:
The swivel lever acts as an intermediary element between the operator's action (rotating the axle) and the cogwheel blocking function. The cam disc on the axle serves as another intermediary that translates rotational motion into linear motion to move the swivel lever between blocking and free positions. These intermediary components enable safe operation sequencing while maintaining manageable system complexity.
2Reliability
If a key lock and rotating axle mechanism is used to control access, then unauthorized operation is prevented, but ease of operation decreases
Solution Approach 1:
The key lock must be used first to unlock the rotating axle before the earthing switch can be operated. This preliminary action ensures that only authorized personnel can access the switch, providing security while maintaining a clear, sequential operation procedure that is easy to understand and follow.
Solution Approach 2:
The rotating axle with cam disc provides dynamic control over the swivel lever position. The cam disc profile is designed to automatically move the swivel lever from the blocking position to the free position when the axle is rotated in the correct direction, enabling smooth and intuitive operation once the key lock is unlocked.
3Reliability
If the swivel lever is continuously pressed against the cogwheel by a spring, then blocking reliability is improved, but force requirements increase
Solution Approach 1:
The spring acts as a counterweight providing continuous blocking force against the cogwheel through the swivel lever. This elastic counterforce ensures the lever remains firmly engaged with the cogwheel teeth, preventing any backplay or unintended movement while the spring's elastic nature allows it to accommodate operational movements without requiring excessive force.
Solution Approach 2:
The spring's continuous pressure, which might seem like an unnecessary force requirement, actually provides the benefit of ensuring positive engagement between the swivel lever and cogwheel. This continuous force prevents the lever from disengaging accidentally and ensures reliable blocking, converting the potential disadvantage of continuous force into the advantage of guaranteed engagement.
4Reliability
If the interlock system requires specific sequence of actions, then unauthorized operation is prevented, but productivity decreases
Solution Approach 1:
The required sequence (unlock key lock → rotate axle → move swivel lever → operate switch) ensures security by preventing unauthorized operation. However, once the operator has the key and understands the procedure, the actions flow naturally in sequence without delays, minimizing the impact on operational efficiency while maintaining robust security.
Solution Approach 2:
The cam disc profile is designed to automatically guide the swivel lever through its motion path when the axle is rotated. This self-guiding mechanism eliminates the need for complex control systems or multiple manual steps, allowing the operator to simply rotate the axle and the interlock mechanism handles the rest, minimizing the time and effort required for the security procedure.
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 interlock system securely prevents unauthorized operation by ensuring the earthing switch can only be transitioned between open and closed states through authorized means, enhancing safety and reliability by preventing intermediate state locking and allowing easy integration with existing substation equipment.
Implementation Method 1
a spring having an extremity secured to the swivel lever and another extremity secured to the housing to continuously press the swivel lever against the cam disk
Implementation Method 2
the inner extremity of the rotating axle carries a cam disc cooperating with the swivel lever to move it from its blocking position to its free position and conversely upon rotation of this axle
Implementation Method 3
the end of the swivel lever comprises a pinion to be meshed with two meshed cogwheels of the actuation mechanism when the swivel lever is in the blocking position
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to an interlock system (1) to block or free a cogwheel of an actuation mechanism of an earth switch for gas insulated substation, this interlock system (1) comprising a housing (4) enclosing : - a swivel lever having an end moveable between a blocking position pressed against the cogwheel, and a free position at a distance from the cogwheel ; - a rotating axle movable between a blocking position and a free position, this axle having an inner extremity carrying a cam disc to move the swivel lever, and an outer extremity protruding out of the housing (4) to actuate this axle ; - a spring having an extremity secured to the swivel lever and another extremity secured to the housing (4) to press the swivel lever against the cam disk ; - a key lock (8, 9) secured to the housing (4) and cooperating with the axle (21) to lock it in its blocking or free position.