Box-Type Substation Key Interlock for Safe Transformer Maintenance
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Solution Overview
Problem
The interlocking design of existing box-type substations is complex, requiring maintenance personnel to read operation guides, which hinders quick maintenance and increases time during emergencies, affecting maintenance efficiency and safety.
Innovation Solution
A simplified mechanical lock interlocking system with keychains and locks that ensure circuit breakers, disconnectors, and grounding switches are sequentially switched off and locked, allowing for safe and efficient maintenance without guides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex interlocking logic with multiple conditions is used to ensure maintenance safety, then safety of maintenance personnel is improved, but device complexity and operation time increase
Solution Approach 1:
The interlocking system is segmented into multiple independent keychains, each associated with specific circuit breakers or disconnectors. Each keychain independently controls its associated device, eliminating the need for complex centralized interlocking logic while ensuring safety through distributed control.
Solution Approach 2:
Keychains serve as intermediary physical objects that mediate between the operator and the circuit breakers/disconnectors. The keychains must be transferred between devices in a specific sequence, providing intuitive physical guidance for safe operation without requiring complex logical conditions or reading operation guides.
2Reliability
If complex interlocking logic with multiple conditions is used to ensure maintenance safety, then safety of maintenance personnel is improved, but loss of time during maintenance operations increases
Solution Approach 1:
The keychains are pre-associated with specific circuit breakers or disconnectors before maintenance operations begin. The physical presence of keychains on devices indicates their status, and the required keychain transfer sequence is predetermined, allowing operators to perform maintenance without reading operation guides or performing complex logical checks during emergencies.
Solution Approach 2:
The system provides self-guided operation through physical keychain constraints. The keychains automatically guide operators through the correct sequence of operations by being physically attached to specific devices, eliminating the need for external operation guides or complex interlocking logic verification during maintenance.
3Reliability
If keychains are locked at circuit breakers when switched on, then prevention of misoperation is improved, but ease of operation decreases
Solution Approach 1:
The keychains are designed to be automatically locked at circuit breakers or disconnectors when they are in the switched-on state, preventing premature removal or transfer. This preliminary anti-action ensures that operators cannot accidentally operate devices that are still energized, while the locking mechanism is designed to be simple and intuitive, requiring only straightforward insertion and removal actions when appropriate.
Data Source
AI summary
A box-type substation, an energy storage power supply system, and a photovoltaic power generation system. The box-type substation includes a low-voltage cabinet, a high-voltage cabinet, a transformer, a first keychain, and a second keychain. When two circuit breakers in the low-voltage cabinet are in a switched-on state, each of the first keychain and the second keychain is locked at a corresponding circuit breaker. Therefore, when maintenance is performed on the transformer, the circuit breakers in the low-voltage cabinet are switched off first to remove the first keychain and the second keychain. Then, the first keychain and the second keychain are used together to switch off a disconnector in the high-voltage cabinet, and the first keychain and the second keychain are locked at the disconnector when the disconnector is in a switched-off state. Mechanical lock logic of the box-type substation is simple with high efficiency.