APTP Articles

Safety by Design

With technical innovation comes switchgear advancement. The increasing demand for fixed pattern Primary Solid Insulated Switchgear (SIS)

Typically, AIS or Air Insulated Switchgear has been traditional choice for Primary Switchgear installations both national and internationally. AIS switchgear offered the operator visual isolation of the circuit protective device via either a withdrawable vacuum circuit breaker (VCB) or with withdrawable vacuum contactor (VC).

Air Insulated Switchgear – Since the 1960’s+

Traditional Medium Voltage AIS withdrawable switchgear also provides required high operational current ratings up to and exceeding 4,000A with both Internal short circuit and internal arc containment ratings of up to and surpassing 40kA/3seconds and 40kA/1second respectfully.

Since the mainstream introduction in the 1960’s of AIS type switchgear, refinements have only come from advancements in it base components, IAC venting and assemblies and mostly by the implementation of standards such as the IEC 62271 series, however for the most part AIS switchgear is large and requires a generous footprint which has a knock on effect for switchrooms and supporting infrastructure.
The design basis of Air Insulated Switchgear is the requirement for generous dimensions between phase conductors and between conductors and metallic or earthed potentials of the switchgear as is typically defined in AS2067 Table 3.1 as applicable to voltage range.
Basically, AIS switchgear has a larger footprint as it utilises an air gap as the insulation medium that provides the dielectric stability of the system.

Solid Insulated Switchgear – GELPAG MSS the new Primary Switchgear of 2021+

As an international leader in switchgear research and development, GELPAG Advanced Technology GmbH 2019+ has announced the release in 2021 of the MSS (SIS) Solid Insulated Switchgear. Co-designed by GELPAG and European switchgear experts the MSS is marketed in Australia as the POWINS MSS12 and MSS36 (36kV currently in R&D).