VCB & Isolating Switches in 110kV Substation Renovation

2025-06-03 13:35:31

The following is a practical summary of the collaborative application of Vacuum Circuit Breakers and isolating switches in a 110kV substation renovation project, combined with technical selection solutions:

1、 Background of transformation and necessity of collaboration

Pain points of old equipment

The original substation used traditional SF6 circuit breakers and independent isolating switches, which posed a risk of gas leakage (GWP=23500), and the reliability of mechanical interlocking was low. Therefore, expansion requires a total power outage of 69%.

The operation of the isolation switch once caused an arc reignition accident due to a grounding fault (case: misoperation of a 110kV station resulted in an explosion of the switchgear).

Collaborative design objectives

Security enhancement: Through the dual safety mechanism of "circuit breaker disconnection+physical isolation of isolation switch", the risk of tripping under load is eliminated.

Environmental upgrade: Replace SF6 equipment with vacuum Circuit breakers and use modular isolation switches to reduce greenhouse gas emissions.

Flexible expansion: supports uninterrupted expansion of GIS equipment, reducing power outage losses during the renovation period.

2、 Core equipment selection and technology integration

(1) Vacuum circuit breaker: 126kV environmentally friendly vacuum circuit breaker

Technical parameters: rated current 3150A, breaking capacity 40kA, power frequency withstand voltage 230kV+73kV, GWP ≤ 1 (CO ? insulation).

Innovation point: The single break arc extinguishing chamber solves the compatibility problem between insulation and current flow, and is suitable for environments in high-altitude mountainous areas at -30 ℃.

(2) Isolation switch: Three position isolation switch (GW4 optimized type)

Function integration: Merge isolation/grounding/disconnection functions, operating torque ≤ 150N · m, mechanical life 10000 times.

Error prevention design:

Mechanical locking: prevents the isolation switch from being operated when the circuit breaker is closed.

Electrical interlocking: linked with the relay protection system, the fault locking isolation switch is activated

(3) Collaborative layout plan

Space optimization: The circuit breaker and isolation switch are arranged vertically, saving 40% of the floor space (compared to traditional AIS).

Interface standardization: Reserved PASS modular interface, supporting later plug-in expansion (such as adding new energy outlet intervals)