Electrical Engineering Articles  
ElectricalSchool.info - a large educational project about electricity and its use. Through our site you will not only go into topic, but also fall in love with electrical engineering, electronics and automation!
Electrical and magnetic phenomena in nature, science and technology. Modern electric power industry, arrangement of electrical appliances, devices and installations, industrial electrical equipment and power supply systems, electric drive, alternative energy sources and much more.
Electrician Schools | Electrical Engineering Articles | Contact

Top Articles In Electronics and Electrical Engineering. Journal of Electrical Engineering & Technology.
Electrical engineering is the branch of engineering that deals with the technology of electricity, including circuitry, power generation, machine control and communications. On our website - collection of technical articles related to electrical engineering, electricity, power and voltage, power substation, electric drive, electric lighting, energy efficiency and alternative energy.


 Electrician Schools / Electrical engineering / Siemens Energy Clean Air Switchgear

Siemens Energy Clean Air Switchgear

"Clean Air" as insulation in switchgear

A switchgear is an electrical installation designed to receive and distribute electrical energy of a specific voltage class. Such an installation includes switching devices, connecting buses, auxiliary devices for relay protection and automation, as well as measuring and accounting tools.

There are switchgears assembled from standard unified cells of a high degree of readiness; such switchgears are called complete switchgears. They occupy a small area under them, so they are well suited for indoor installation.

The usual complete switchgear is a metal box, divided inside into four compartments, located one above the other. In the input compartment there are cable terminations and measuring transformers (current transformers). Distribution busbars are located in the busbar compartment. In the high-voltage circuit breaker compartment there is a power circuit breaker with arc chutes directly.

Siemens Energy Clean Air Switchgear

Siemens Energy Clean Air Switchgear | Source: Siemens Energy

Typically, the circuit breaker is mounted on a withdrawable element, which is accessed using a special key with several levels of protection. Finally, in the relay compartment there are low-voltage relay protection and automation devices, switches, knife switches. On the door of the relay compartment are located: lighting equipment, mnemonic diagram, electricity metering and measurement devices, as well as elements of microprocessor control of the cell.

Device elements under voltage from 1 to 35 kV are traditionally made using air-insulated busbars. However, it is especially worth noting gas-insulated switchgear (GIS), produced for voltages from 6 kV and above - up to 800 kV.

"Clean Air" as insulation in switchgear

SF6 is SF6 (sulfur hexafluoride). This gas is non-toxic, non-flammable, almost completely harmless, but most importantly, in the context of switchgear, it has excellent arc-extinguishing and electrical insulating properties: the electrical strength of SF6 gas is 2.5 times higher than that of air. Its use, especially in cells of complete switchgears for high voltage (from 110 kV and above), makes it possible to make them more compact compared to devices without SF6 gas.

Elements of complete switchgears with SF6 insulation are enclosed in hermetic grounded shells, inside which the environment of the element is represented by SF6 gas under pressure up to 0.6 MPa. Since the 2000s, gas-insulated switchgear has been widely used throughout the world.

And everything would be fine, if not for some features of the SF6 gas. Firstly, it has a limitation on the lower operating temperature of the ambient air: it should not be lower than -5 оC, therefore, it becomes necessary to install complete switchgear indoors or even underground. But it's not so scary. The second feature of SF6 is that it belongs to the so-called greenhouse gases. It is this fact that some switchgear manufacturers have adopted, despite the fact that the volume of SF6 production in the world is quite small, and the contribution of sulfur hexafluoride specifically to global warming does not exceed 1/500.

In particular, Siemens Energy recently received an order from BKK Nett in Norway to supply the world's first complete switchgear for voltages up to 145 kV with no SF6 insulation. A unique switchgear with "clean air" insulation (the synthetic gas mixture will contain 80% nitrogen and 20% oxygen) is planned to be installed at the Koengen substation in Bergen, which is supposed to supply electricity from renewable sources to Norway's largest port for cruise liners.

The officially declared reason for the rejection of SF6 is that this gas is one of the greenhouse gases, and for the sake of the environment, it is necessary to abandon its use in switchgear. The idea has already been picked up by many manufacturers of complete switchgears.

Siemens Clean Air - New insulation medium for blue GIS: