Digitalization and SF6 free applied to Medium Voltage Switchgears

We live in a world with great demand for energy solutions. These solutions are already there, delivered, and ready to be delivered for new demands. But this fact is only one side of the coin meanwhile the other side is that we are running out of resources and severely damage our planet through keep satisfying our demands with the same old solutions. This goes in all our life routines.

In this article I want to focus on medium voltage solutions and how to keep responding to the increasing demand meanwhile saving our planet.

I will discuss 2 main initiatives; first one is digitalization and second one is SF6 free solutions.

1.??????Digitalization:

????????????????????????????????I.???????????What does it mean?

??????????????????????????????II.???????????Does automation the same as digitalization?

????????????????????????????III.???????????Examples and benefits.

2.??????SF6 free:

????????????????????????????????I.???????????Why engineers use SF6 SWGs?

??????????????????????????????II.???????????Is there a difference when we say SF6 SWG or GIS?

????????????????????????????III.???????????Why we shall stop SF6?

???????????????????????????IV.???????????Example and benefits.

Digitalization:

What does it mean?

Digitalization is mainly about shifting from traditional solutions to new smart and more eco-efficient solutions. Why? The answer is that by shifting to digital solutions you already improve the reliability of your systems, reduce downtimes, improve safety and shifting from routine maintenance plans to smart predictive maintenance approach.

Does automation the same as digitalization?

For the 1st time it sounds logic to think digitalization as the automation systems. But digitalization is much wider concept to be limited to automation scope.

Most will perceive automation as systems like RTU and PLCs. That is right for automation. But when we talk about Digital switchgear we are talking about wider approach.

In digitalization we are thinking about the smart systems. Equipment that can have dialogue with the operator. Innovators are thinking is what makes it easier for the operator to interact with his assets of SWGs. Thus, one of the main points you must consider is what most issues you face when operating SWG and what is its root causes. Based on that innovators start to generate solutions for SWG to reduce the probability of occurrence of these root causes.

Among many solutions in digital SWGs is the condition monitoring allowing you to keep monitoring the main critical SWG conditions such as temperature of connection points, partial discharge, and circuit breaker condition monitoring. Keep an eye on these parameters is great value add to operators, utilities, and owners.

Another aspect of digitalization is shifting from using traditional components like current and voltage transformers to using current and voltage sensors. Great benefits are captured with these new devices as below:

·????????Higher safety by shifting from secondary current of 1 or 5 Amp and risk for leaving the secondary circuit open with all its consequences to secondary value of 150 mv @50 Hz connected via RJ45 cable.

·????????Faster delivery and lower technical specifications risks. This is based on the fact of these sensors normally work in a range. So as long you specify the circuit breaker rated current, then no need to go in the sophisticated calculations of CT ratio, burden and accuracy. This help in many aspects mainly manufacturing can start immediately getting your SWG on site fast responding to the fast-track project demanded now.

·????????Reduce cost of last-minute change. Many of us faced the situation of approving submittals and during FAT, we see a real system and may demand some changes. These changes can be in CT ratio based on updated load list which was dramatic change with traditional CTs as it comes with great cost and time delays. Or change in the operating sequence logic which its severity varies with the scope of the change. Even this operation change can be done as in digital SWG, traditional control circuits are being replaced by the IED to carry all the functions including the sequence of operation. So, change in the logic is a matter of programming change that can be done using IEC61850 by commission engineer over a short break after which new system can be tested and verified.

·????????Lower operating costs. This comes from the fact of having SWG ready for future demand change. Remember that sensors are working in range of current. So after 3 or 5 years if you face increased demand, you will only need to re adapt the IED setting and keep your system running. In traditional CT, you should purchase new CTs (cost+time) and shutdown your SWG to install the new CTs then test it (cost+time). So, by purchasing digital SWG you are investing not only in having world class solutions but also you are reducing your operating costs and improving your system reliability.

·????????Reduce your electricity bill through reducing loses. Yes, with traditional CTs you are paying money for losses in the CTs. It is being said that replacing CTs with Rogowski coil sensors for 14 MV panels can contribute to saving you around 250 MWH losses over SWG lifetime.

·????????Reduce civil works. Set of 3 VT + set of 3 CT weight on average of 135KG. if you replace them by current and voltage sensors this will dramatically reduce to average of 7.5 KG. This great reduction in weight shall be a dream for your civil engineers.

·????????CTs accuracy used to be ranging from standard values starting from 5P10 to 5P30 in very rear cases. Current sensor accuracy can reach up to 5P630. A magic, is not it?

A lot of other benefits of digitalization and this may be why digitalization is considered as the new industrial and technological revolution. So, the key message is that digitalization is not only automation, but it is much more.

Example and benefits:

I will refer to ABB Medium voltage SWG type UniGear digital. The key benifits can be summarized as below:

1. Comply with specifications and standards
2. Keep project time schedule
3. Keep cost targets
4. Flexible to changes
5. Maximize integration

SF6 free solutions:

Why engineers use SF6 SWGs?

The normal solutions of SWG business is to deliver Air insulated SWG (AIS) achieving all the needed clearances specified in the international standards. But in some cases, customer may have limitations for the space putting great constrains on the SWG dimensions. To address these challenges, many solutions were developed including Fixed CBs, double level arrangement and most common is to shift to Gas Insulated Switchgear (GIS) in which air is being replaced by gas having higher electrical strength reflecting in reducing clearances and thus reducing SWG dimensions.

When innovating such GIS solution, SF6 was identified as the best alternative to be used.

Is there a difference when we say SF6 SWG or GIS?

The answer is very straight-forward; NO. GIS is technology as said before using gas instead of air to reduce SWG dimensions. SF6 was the original used gas, but technology elaborate over time. So when you specify GIS please do not get your-self trapped by stating SF6 because doing so limits your profitable investment.

Why we shall stop SF6?

It was proved that SF6 has its GWP 23,500. It means that SF6 is severely contributing to the warming of our planet. That fact encouraged international leaders and unions to start asking for alternatives for SF6 and it is being said in many global supplier sustainability reports that they are targeting to stop SF6 products within the coming few years. Even it is target identified by governments and the Europe is a clear example driving that initiative.

Example and benefits:

Here I can give an example with ABB MV secondary switchgear SafeRing/safePlus Air/Airplus. This SWG is offering fully GIS solution free of SF6 replacing it with dry air.

Dry air has GWP <1 compared to SF6 has GWP 23,500

Finally, you must ensure that both solutions, digital and GIS eco-efficient; are fully comply and type tested according to the relevant IEC of each component and mainly IEC 62271-200 for SWG up to 52 KV.

Technology is there, tested and has huge installed based and all it takes you to decide.

In the links below, I am leaving some valuable links to examples of ABB solutions.

ABB ability, Electrification portal:

https://new.abb.com/about/our-businesses/electrification/abb-ability

UniGear Digital web app:

https://new.abb.com/medium-voltage/unigear-digital

ABB SafeRing/SafePlus Air/AirPlus

https://search.abb.com/library/Download.aspx?DocumentID=1VDD006404%20EN&LanguageCode=en&DocumentPartId=&Action=Launch

Mostafa Khater