Page 59 - Energize July 2022

TECHNICAL

were to be a cable fault, for instance, the Siemens RMU would the proven properties of GIS in their networks and want to use
vent through a tube to the top of the cabinet. The operator, who insulating media free of fluorine gas; at the same time 8DJH 12 can
would be standing in front of the unit, would be protected from be controlled from remote, is communication-capable, and can be
harmful material or particles of steel, and flames, because all linked with IoT platforms such as MindSphere, the cloud-based,
these things would vent to the back of the ring main unit and exit open IoT operating system from Siemens, and with other systems
at the top, away from the operator. as well. Furthermore, it offers a possibility for the integration
Another important safety feature is the set of interlocks on of components for condition monitoring and distribution grid
the doors. An operator cannot simply open a door and have automation, an innovation with far-reaching benefits.
access to live conductors. One has to physically switch it off and
isolate it before you can test the cable. The cable compartment Please tell us more about how MindSphere supports Internet of
has a handle, and the cable test compartment has another Things (IoT) technology. What is a typical application?
handle. It’s important to have these built-in safety features and Software integrators can develop applications that fit on top
interlocks. of MindSphere. It can be easily integrated with our ring main
An additional feature to note is the manometer on the front units. It might be a conveyor belt in a production plant, or a
of the cabinet. This indicates whether gas is present or not. It robot in automotive factory, or indicator lights, meters, etc. So
doesn’t provide any specific pressures or anything, it just shows it’s essentially a data gathering service. And on top of that we
green or red. If it’s green, you can operate, if it’s red, you can’t can have anybody writing applications for specific functions. And
operate because you don’t have any gas in it anymore, which I think this is one of the things what we are seeing especially
means it might have been damaged. with the municipalities. They need visibility to what is happening
Furthermore, this series of RMUs have earthing levers. Say at their substations. They can identify an outage quickly and
you want to operate the earth switch. To do so, you have to pull send someone to repair it. Siemens’ RMUs can potentially assist
a lever and indicate that you will switch the earth on. But because municipalities to have better visibility, very quickly, of their
it has a three-position switch you can’t connect a live cable to distribution articulation network.
earth. It’s designed as a safety feature. There is also a specific
module, a little self-powered relay which will reveal an earth fault Are any of these RMUs in operation in South Africa yet?
and overcurrent faults. So that’s one of the benefits as well. Yes, Johannesburg’s City Power and Ethekwini Municipality use
These RMUs also have voltage present indicators (VPIs). these RMUs already.
This contains a capacitor divider on the bushing, which senses
a voltage on the cable. In this way, the operator knows that Do any of the local minisub manufacturers use these RMUs?
the cable is live and shouldn’t go put it to earth. There are also Yes, Revive Electrical Transformers use Siemens RMUs in the
interlocks blocking that prevents operators from putting a live minisubs they supply to City Power and other customers. By using
cable to earth. Same with the circuit breaker. Siemens RMUs, Revive Electrical Transformers offer a completely
type-tested solution.
Is the use of clean air instead of SF6 unique to Siemens or will
this become an industry norm? What services does Siemens offer in terms of training and product
There are other OEMs looking at gas-free equipment, but usually backup for these RMUs in South Africa?
there’s still some sort of sulphur gas that they are using. We say Siemens offers the training a lot of the utilities ask for in their
ours is clean air, which means that its components are the same tender documents. When we offer training for the operators, we
as you would breathe, although it is under pressure. There are show them a video which demonstrates all the product’s benefits.
still some other OEMs which make use of GIS vacuum breakers, We also have a demo trailer, which contains a ring main unit. We
and SF6 vacuum breakers as well. These would have a SF6 breaker open the doors and give an operating handle to the operator and
inside either air or SF6. Siemens only makes use of vacuum let them touch and handle the RMU to become accustomed to it
breakers. That is something that sets Siemens apart. Clean while it’s off and safe to play with. We show them physically how
air consists of the natural elements of the ambient air and is the unit works – providing real hands-on training.
therefore free of F-gases, with a global warming potential of less
than 1, highly stable, non-toxic, non-flammable, and suitable for Thank you Deon and Gert for answering these questions. We hope
every application temperature. our readers get excited about the new Siemens 8DJH-12 RMU and
contact your sales department soon.
What applications are these RMUs suited to?
Possible applications are secondary transformer substations, For more information about Siemens 8DJH product family,
customer transfer sub-stations and switching substations, as please contact Althea Borman, Siemens, Phone 011 652-2000,
well as industrial and infrastructure facilities that benefit from althea.borman@siemens.com, www.siemens.com

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