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TECHNICAL

Blue GIS: What is it and how does it work?

Energize spoke to Deon Henriksen and

Gert Hoffman recently regarding Siemens new
“Clean Air” RMUs

Many switchgear manufacturers still use SF6 as an insulating
medium because it has such a high dielectric strength that the
device can be very compact. Does the use of clean air as an
insulating medium mean that the unit becomes physically larger
Deon Henriksen Gert Hoffman than an equivalent SF6-filled one?
The concern for the environment is such that Siemens is putting in
Hello Deon and Gert. Thank you for speaking to Energize about a lot of effort to ensure that sustainability is there. Blue GIS makes
Siemens’ latest Ring Main Units (RMUs). Please introduce use of clean air under pressure, so it still has many of the benefits
yourselves to our readers. of a gas insulated switchgear set. And in terms of clean air, that’s
Hi Roger, my name is Deon Henriksen. I am the Vice President of what it is – clean air, with the components that you would find in
Electrification and Automation for Siemens Smart Infrastructure. natural air: oxygen and nitrogen. Clean air load-break switchgear
Gert Hoffman is the technical sales manager for Electrification & with compact dimensions which is environmentally friendly and
Automation, Siemens Smart Infrastructure. maintenance-free for life, featuring a high level of operational
reliability, personal safety, and availability. The hermetically sealed
Thank you. It’s a pleasure to speak to you today. I understand welded switchgear vessel makes the parts carrying high voltage
that this new series of RMUs uses plain air as an insulating gas. insensitive to ambient conditions and prevents the ingress of
Tell us more about that please. foreign objects.
The Siemens 8DJH product family has been used by customers
worldwide for more than ten years. Now, the 8DJH-12 expands All switchgear must comply to certain local and international
this portfolio. It is a switchgear using clean air – an insulating gas standards. What standards does Siemens’ new range comply with?
exclusively consisting of natural elements of the ambient air. The use This is the first ring main unit to comply fully with the latest SABS
of clean air ensures easy operation throughout the entire lifecycle. standard with cable testing. That is, SANS 1874. We obviously
Thus, the new 8DJH-12 combines the sustainability of the “Blue GIS” expect to do well in the market with this product. There are still
portfolio with the advantages of the proven 8DJH product family. some challenges that accompany the introduction of a new product
into the market, but we are proud that it was the first ring main
The term “Blue GIS” is interesting. I imagine many people might unit to comply fully to the latest SABS specification with the cable
be surprised by the term ‘blue’ and expect the word ‘green’ to test facility.
have been used. What’s the reason behind the choice of blue?
The new 8DJH 12 belongs to the “blue” portfolio of Siemens. Every What voltages can these RMUs be used with?
GIS of this portfolio is equipped with clean air and the proven There are many design concepts which need to be considered
Siemens vacuum technology. It meets the expectations of Siemens’ to allow us to use clean air, even though, like I said, it is under
customers with respect to switchgear availability, maintenance-free pressure. We’ve achieved it with the 12 kV version, and we’ve
design, personal safety, environmental independence and cost- succeeded now with the 24 kV version. We are still busy working
efficiency. Sustaining the environment is important to Siemens, on the 36 kV version. The 8DJH-12 is a factory-assembled, type-
particularly as South Africa moves towards the energy transition tested, and 3-pole metal-enclosed RMU using clean air rated at 12
with renewables. This must be considered at a product level too kV, 20 kA and 630 A. The switchgear is used in public and industrial
and at Siemens, we’re developing answers to these environmental energy systems of the secondary distribution level.
challenges with Blue GIS, with clean air. When equipment is
decommissioned after 20 or 30 years, some people simply discard Besides the use of clean air instead of SF6, what other new
the equipment. Often, they don’t have a policy in place to get rid of features do Siemens 8DJH RMUs offer?
the SF6 gas, so they just break it and let the gas dissipate into the Siemens 8DJH RMUs incorporate a number of important safety
air. But you’re supposed to have a recycling plan. Siemens extracts features. The first is the new venting system. Our latest RMUs
the gas from the equipment before recycling the metal parts. have a special built-in arc-vent at the back of the cabinet. If there

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