Armored Metal-Clad Enclosure — Fault Containment by Design
The cabinet is built as an armored metal-clad structure that physically isolates the busbar, circuit breaker and cable compartments from each other. If a fault develops inside one compartment, the metal partitions contain the event to that compartment and stop it propagating to adjacent cells. This is the same containment principle that lets the panel carry its 31.5kA / 1s internal arc rating, and it is why metal-clad construction remains the accepted standard for 24kV primary distribution rather than metal-enclosed alternatives.
Complete HV / LV Compartment Separation with Double-Sided Maintenance Access
The high-voltage compartments (busbar, breaker, cable) and the low-voltage control compartment are separated by grounded metal barriers with sealed cable transitions. Control wiring, protection relays and communication modules in the low-voltage compartment can be worked on with the panel energised on the HV side. The cabinet is dimensioned for double-sided access: cable terminations, current transformers and the low-voltage compartment are all reachable from the appropriate side without disturbing adjacent panels in a line-up, keeping the overall footprint compact.
4000A Main and Branch Busbar with 40kA / 4s Short-Time Withstand
The main busbar and the branch busbar are both rated at 4000A, so the assembly handles heavy incomer duty and heavy outgoing feeder duty in the same physical framework. Short-time withstand reaches 40kA for 4 seconds with a matching 100kA peak withstand — a fault-level headroom that suits 24kV grid-connection points and industrial plants where upstream protection may take several cycles to clear a bus fault.
IAC 31.5kA / 1s Internal Arc Resistance
The assembly is type-tested to internal arc classification 31.5kA / 1 second. Pressure-relief flaps direct expanding gases upward, away from the operator zones at the front, rear and sides of the panel. The ventilation pathway is co-designed with the pressure-relief path, so normal thermal air movement and abnormal arc pressure relief share a coordinated exhaust route — this is why the cabinet can carry a full internal arc rating without derating current under normal service.
AG5 (9-Degree) Seismic Rating — Highest Standard-Tier
Seismic performance reaches AG5, corresponding to the 9-degree earthquake intensity level under the Chinese national criteria. This is the highest standard seismic tier for medium voltage switchgear and applies to the most demanding seismic-zone installations without additional structural bracing at the switchgear line-up. Trolley interlocks, door hinges and busbar supports have all been type-tested to remain functional after the seismic loading test cycle.
Modular Breaker Trolley with Selectable Main Switching Device
The breaker truck follows a modular design with a simple, high-endurance mechanical structure. Main switching device is selectable per project: vacuum circuit breaker for standard duty, vacuum contactor for high-cycle motor switching duty, or load-break switch trolley for cable network switching. Because the trolley interface is standardised across the switching options, a future upgrade or type change (for example, replacing a contactor with a full breaker when load characteristics evolve) is a same-day activity.
Comprehensive Five-Prevention Interlocking with Closed-Door Operation
A complete mechanical and electrical five-prevention interlock is built into the breaker trolley, earthing switch, cable compartment door and shutter mechanism. Operators cannot rack the breaker in or out with the primary contacts closed, cannot close the earthing switch onto a live circuit, and cannot open the cable compartment door until the circuit is isolated and earthed. Full closed-door operation is supported, so routine switching does not require the operator to open any high-voltage compartment.
Motorised Operating Module for Remote Drive
A motorised operating module can be fitted to both the breaker trolley and the earthing switch. This allows remote or scheduled operation of the primary switching devices from the substation SCADA — useful in unmanned or lightly-attended substations, and essential in installations where operator access to the front of the panel is restricted (elevated platforms, hazardous-atmosphere rooms).
Full-Stack Digital Layer — Mechanical, Thermal and Partial Discharge Monitoring
The assembly is instrumented as a digital medium voltage switchgear from the design stage. The sensor stack covers breaker mechanical characteristics (travel curve, coil current, operating timing), one-key sequential control, visualised HMI operation, cabinet temperature monitoring, and partial discharge measurement. Data is automatically collected, stored and analysed, feeding into power monitoring, energy consumption management and equipment health-state assessment. The operations team gets condition-based signals — rising temperature at a bus joint, changed mechanical timing, drifting partial discharge — so maintenance activity is targeted to panels that actually need it, extending the useful service life of the installation.
