SF6 and SF6 free ring main units, sealed for life.

Cable cubicles from 210 mm wide in a single sealed tank, for compact substations and kiosks where floor area is limited. A 24 kV rated unit also covers 12 kV applications.

Cable cubicles from 315 mm wide for 12 to 36 kV networks, with a 40.5 kV version for the highest distribution voltages.

Cubicles connected one at a time with solid insulated coupling, so boards can grow over time. A slim 406 mm wide version suits confined spaces such as wind turbine towers.

A switch disconnector with high voltage fuses protects distribution transformers, and vacuum circuit breaker cubicles with protection relays serve feeders and larger transformers. Fuse links of 292 mm and 442 mm are accommodated.

Air insulated cubicles for voltage and protection transformers, internal arc classified to 20 kA for 1 second.

The same compact construction and sealed arcing chambers, insulated with technical (dry) air (80% nitrogen and 20% oxygen) instead of SF6, for owners who want SF6 out of their networks without changing substation footprints.

Arc quenching takes place in patented, hermetically sealed chambers, separate from the insulating gas, in both SF6 and SF6 free versions. If pressure drops or the tank leaks, the insulation level falls but the switches keep their full switching capacity, at full load current and down to atmospheric pressure, so the unit stays in service while the leak is repaired. Where the gas also quenches the arc, low pressure means taking the unit out of service. Leaks should still be repaired promptly.

In service in wind turbine tower bases, heavily polluted industrial areas and hot, humid, salt laden coastal climates across Australia, New Zealand and the Pacific, including Darwin. Rated for −25°C to +60°C, with sealed gas tanks and cast resin cable connections that are unaffected by pollution, dust and salt deposits.

A fast acting system senses a pressure rise in the gas tank or cable termination area and closes pre loaded earthing switches on the incoming cubicles, turning the arc into a metallic short circuit within milliseconds, from 30 ms. There is no release of hot gas, no pressure rise against the substation walls and no injury risk. Units are classified to IAC AFLR 20 kA for 1 second, with 25 kA available.

A special patented variant, available as a standard offering, contains an internal arc completely within the unit, with no release of pressure, gas or hot particles from the arc. Because nothing is vented, there is no pressure load on the room, which suits cellars, small kiosks, plant rooms and buildings where no pressure can be tolerated.

Separate devices at separate positions on the front panel remove the risk of a faulty three position mechanism and keep interlocking simple.

Pluggable epoxy resin cones accept screened elbow connectors and surge arresters and can be exchanged on site. Optional galvanic test ports allow cable testing and voltage checks without dismantling terminations, and one operating handle opens the main switch, earth switch and cable cover.

Cubicles can be added later through external cone connections. Motor mechanisms on all switches, including the fuse switch, with position indication, fault detection, load and gas monitoring and remote control through IEC 61850, DNP3 and IEC 60870 5, can be retrofitted on site without changing the dimensions of the unit.

Front accessible fuse compartments, fuse tripping and sealed fuse canisters, temperature rise tested for use with larger distribution transformers.

The surrounding gas is filled at low pressure, so a three way unit holds only about 1.2 kg of SF6, and every tank is leak tested after assembly. The SF6 free range holds none.

Mimic diagrams are painted rather than applied as stickers, so they stay legible and are unaffected by moisture or heat.