Switchgear suitable for use on and offshore

Edited by the Engineeringtalk editorial team Apr 11, 2006

Compact modular metal-clad gas-insulated switchgear developed to meet demand from distribution network operators and industrial users for flexible and expandable, primary medium voltage substations.

ABB's ZX family of compact modular metal-clad gas-insulated switchgear (GIS) has been developed to meet the growing demand from distribution network operators and industrial customers for cost-effective, flexible and expandable, primary medium voltage substations for various applications.

The primary GIS equipment is rated at 3kA, fully temperature rise tested at 40C, making it suitable for applications in the oil, gas and petrochemical industries, both on and offshore.

It also suits applications in utility networks, public buildings, factories and rail infrastructure.

The range covers single busbar (ZX0 and ZX1.2) and double busbar (ZX2) configurations.

With rated voltages from 12 to 40.5kV, rated short circuit currents up to 31.5kA (40kA for the ZX2) and rated currents up to 3kA, it is suitable for utility and industrial installations where electricity is generated or distributed.

Features include laser-welded stainless-steel enclosures, compact modular construction and the introduction of plug-in technology that facilitates simple, controlled connections of busbars, cables, test bushings and voltage transformers.

All maintenance-free live components, such as switching devices and busbars, are contained under SF6 in gas-tight enclosures.

This eliminates the effects of ageing processes and environmental influences to ensure increased operator availability and a long service life, even at high altitudes or in harsh conditions such as offshore platforms.

The design also has easy cable access - accessible from the rear in the ZX1.2 and ZX2 versions - and provision for conventional control and protection devices.

There are dedicated cable test sockets and full mechanical interlocking between the disconnector and earthing selector and the circuit breaker.

Current transformers can be mounted either in the circuit breaker gas compartment or externally on the high voltage cables.

Options are available for current and voltage sensors.

While installing a conventional panel often takes up to two days, a ZX plug-in panel can be installed in less than half a day.

So in typical primary distribution substations, comprising 10 to 20 panels, customers can expect installation savings.

Each panel is supplied as a complete factory-tested unit, so there is no need to work inside high-voltage compartments or handle gas on site.

It reduces the normal 50 installation steps to five.

The modular approach lets users upgrade their network gradually, simply by plugging in more units.

Maintenance times are short compared with conventional switchgear as there is no need to disconnect parts, clean the compartment or refill gas on site.

The ZX1.2 completed a rigorous test programme to gain technical acceptance from the ENA and Network Rail for use at 33kV for ratings up to 31.5kA and 2kA.

Hundreds of ZX1.2 panels were used on the Network Rail Southern Region power supply upgrade project.