Fixed-Type MV Switchgear - XGN Series

The difference is in isolation and maintenance, not in electrical performance. A withdrawable cubicle mounts the breaker on a truck, racks it right out for maintenance, makes the isolating gap by that racking movement, and restores supply quickly by swapping in a spare truck. A fixed cubicle bolts the breaker in place, makes the gap with the isolating switch, and requires the circuit to be dead and earthed before work starts inside. Withdrawable cubicles are larger and cost more, and suit transformer incomers and critical feeders where fast restoration matters; fixed cubicles are simpler, smaller and cheaper, and suit installations with many circuits of ordinary criticality, packaged substations and tight switchrooms. Mixing both in one substation is common.

Start with rated current. XGN2-12 covers 630-3150 A with 20/31.5/40 kA breaking capacity and carries the upper end of both current and fault level among the three, so main incomers and large feeders go there. XGN66-12 covers 630/1250/1600 A with 20/31.5 kA short-time withstand in a 900 x 950 x 2300 mm envelope, about half the volume of a conventional cubicle, and is built for packaged substations, underground substations and small switchrooms. YF-XGN450-12 is a miniaturised derivative, air-insulated and further compressed, suited to ring-main supply units and distribution automation, with its ratings confirmed per project. All three are 12 kV indoor box-type fixed cubicles and can be mixed in one line-up.

XGN2-12 has a high-altitude derivative, written XGN2-12(G). Reduced air density at altitude weakens external insulation, so the derivative is built with increased creepage and clearance distances and the envelope grows to 1200 x 1350 x 2900 mm, while the rated current range narrows to 630/1000/1250 A. Send the installation altitude, the annual minimum temperature and the pollution level together; sites above 2000 m are calculated for insulation coordination on a project basis.

Three things give a preliminary scheme: the medium-voltage single-line diagram, rated voltage with the rated current of each circuit, and the short-circuit capacity with its duration. For a contract-grade quotation, add the cubicle schedule with each panel function (incomer, bus-tie, feeder, metering, VT), the protection scheme and communication protocol, cable sizes and entry direction, control supply voltage, installation altitude and environment, and the standards and document list for the destination market.

It prevents mis-tripping or mis-closing the breaker, switching an isolator on load, applying earth while live, energising onto an applied earth, and entering a live compartment. The XGN series achieves it with forced mechanical interlocking: the isolating switch, vacuum circuit breaker and earthing switch are three independent units interlocked by the mechanism itself, so an out-of-sequence operation is physically blocked rather than merely forbidden by a permit or an electrical circuit. Where additional electrical interlocking or solenoid locks are needed to work with a substation automation system, that is settled together with the technical agreement.

Yes. The main switching device is a vacuum circuit breaker, and the component platform is agreed at project confirmation stage against the technical agreement, with final types, ratings, lead time and document scope following the confirmed component list. The one thing to check alongside it is the mounting interface — changing breaker brand within the same cubicle type does not guarantee the same mounting dimensions, mechanism travel or secondary terminal assignment, and that matters more on a fixed cubicle than on a withdrawable one, because there is no truck acting as a standardised intermediate.

Yes, and fixed cubicles often suit a module better than withdrawable ones — the cubicles are shallower and need no racking aisle, so a module of the same length holds more panels. Switchgear is supplied as equipment while an MV switchgear E-House or power module is supplied as an enclosure: the first is the panel itself, the second covers the enclosure, equipment layout, auxiliary systems and interface integration. Where the line-up goes inside a module as the medium-voltage primary equipment, ETENZ details the line-up arrangement, busbar connections and in-module interfaces, and the delivery boundary is settled once at contract stage.

Standard documents travelling with the panels are the approved project drawings, the single-line diagram, component list, wiring records and packing list. Inspection records are issued to the scope agreed in the order technical agreement; where witnessed tests or a specific report format are needed, raise it during quotation and technical clarification so test and witness slots can be arranged.