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Voltage transformer VT2 – Extension for ARTES test systems

Testing of protection devices with rated voltages up to 690 VLL

With the steady increase in decentralized power generation, the requirements for power distribution are also becoming more complex. Due to the increasing plant power, these are often connected directly to the medium-voltage distribution grid, but the individual generation units of a plant are interconnected at the low-voltage level. This is raised to medium-voltage at the grid connection point by means of a transformer.

The low-voltage used within a generation plant results in a high current load on the cables for long distances between the individual generation units. In order to minimize the associated power losses, the nominal voltage on the low-voltage side is increasingly being raised to up to 690 VLL, in deviation from the widely used 400 VLL.

With an appropriate configuration, many protection systems can also measure this increased voltage directly without additional voltage transformers. This automatically results in new requirement for the test systems. These are largely designed for testing voltage protection functions up to a nominal voltage of 400 VLL. In order that these systems can also be used for testing with higher voltages, an extension is offered with the VT2 to also meet the new requirements.

During the development of the VT2, care was taken to incorporate the advantages of the ARTES RC3 relay test system. Therefore, the VT2 was also fully integrated into a hard shell case and is thus also ideally suited for use under harsh conditions.

Do you have any questions about the voltage transformer VT2? Then contact us by mail to info(at)kocos.com

In addition to the hardware of a test system, the testing software also plays a major role in protection relay testing. Even though simple test tasks can be performed with ARTES test systems without a PC using the integrated operator interface, it is only the combination of hardware and software that provides the full range of functions. The testing software is designed to simplify and automate even complex protection tests.

KoCoS meets these requirements with its ARTES 5 testing software. ARTES 5 enables today’s protection engineers to perform their daily tasks quickly and easily. To this end, ARTES 5 offers a wide variety of features that make testing as efficient as possible. 


ARTES 5 is a database-based testing software. This allows centralized management of all necessary settings as well as results and eliminates the need for manual data management. In addition to a simple folder structure, entire plants including voltage levels and bays can be visualized in the topology. 

For data exchange with colleagues or customers, individual data sets or entire structures can be exported from the database to a file. In turn, the information contained can be viewed and edited without importing it into the user’s own database. 

All in One

With the increasing complexity of protection functions, the testing software must provide the user with more and more new tools. In ARTES 5, these tools are known as monitors, and various monitors adapted to different protection functions are provided. All available monitors are included in the standard scope of delivery and do not have to purchased additionally by the user. Regular updates, some of which include new monitors, are also provided free of charge. 

Of course, the ARTES 5 testing software offers much more. For a detailed presentation of ARTES 5 our specialists are at your disposal. Contact us via the comment function or by mail to info(at)kocos.com

The comparison of actual test systems shows that the technical data of the devices from different manufacturers are similar in many points. And there are specifications where the devices differ to a greater or lesser extent. When evaluating, however, it should always be questioned what this means for the practical use of the devices.

Specifications as a result of development

In some cases, the technical data are much higher than required by the application. And this was not always the aim during development. Rather, some values are just the result of the development, quasi what has come out.

USPs without added value

And there are certainly manufacturers who deliberately work towards generating "unique selling points", which in the end, nobody needs. A real USP only becomes more important when the existing advantages also offer added value and a special benefit for the customer.

Technical data does not tell the whole story

Technical data are easy to compare. But purely numerical values say not much about which product is best suited for the customer. Product features and properties that cannot be evaluated with numbers, or only with difficulty, often lose their importance in the comparison. And it is often here where the advantages can be found that offer real added value for the customer.

Real USPs are not easy to find

The special features of our ARTES testing systems are pointed out in brochures, articles or blog posts. Customers appreciate, for example, that ARTES can be operated in an upright position. The status LEDs in the front or the operation of our devices on DC supplies are also appreciated by many users.

These properties and the many features and functions of ARTES are often not known. For example, the internal control unit, the low-level outputs, the analogue inputs, the multifunctional inputs or the internal GPS synchronisation unit are already included in the standard scope of delivery of the ARTES 600. In competing products, these features are often found, if at all, as options for which a charge must be paid. ARTES also scores points, for example, with its very low noise level, a feature that is difficult to express in numbers.

The software matters

The software plays a major role in relay testing. The device hardware of a test instrument is primarily a freely programmable function generator. Even though ARTES offers much more with its on-site operation, the test software in the end makes a decisive contribution to the high functionality of a professional testing system.

The ARTES 5 software is not only convincing because of its many useful features. It also has the most advanced user interface and the most intuitive operating concept. With ARTES 5, the user reaches his goal faster and easier, and thus saves time. In a following blog post, we will focus on the features and advantages of the ARTES 5 testing software.

ARTES experience live

The special features of ARTES are also highlighted regularly in social media such as Facebook, LikedIn, Twitter or YouTube. However, a live demonstration also offers the opportunity to find out what a customer's requirements and needs are. Only then is it possible to work out the features of ARTES that are important for the customer and to demonstrate their benefits.

Particularly in view of the diverse functions of the software, we are always pleased to offer our customers practical product presentations. Here, the customer not only learns a lot about ARTES, he can also experience ARTES live.

Answer: Nothing! Because when we talk about GOOSE at KoCoS, we usually don’t mean the animal but the network protocol I protection technology. Further answers to the question of what GOOSE is all about and what role the latest ARTES update plays in this context can be found here. 

The IEC 61850 standard of the international Electrotechnical Commission (IEC) describes, among other things, a general transmission protocol for protection and control technology in medium and high voltage substations (station automation). One topic of this series of standards is the “Generic Object Oriented Substation Events”, in short GOOSE messages. 

But what is the significance of these GOOSE messages in a substation? 
In simple terms, GOOSE messages are used to exchange information such as status messages or excitation signals between the IEDs (Intelligent Electronic Devices) of the station. These information are distributed as an Ethernet packets via the process bus of the substation.

With an update to follow in the next few days, the test systems of the 4th ARTES generation can also be integrated into a corresponding environment to evaluate these signals. Thanks to the powerful signal processor of these test systems, they can be connected directly to the process bus, so that the evaluation of GOOSE messages can take place in real time.

Since a large number of GOOSE messages can be present in a network, but only the information of individual ones is of interest for the protection test, the exact structure of the required GOOSE message must be known. For the correct parameterization of ARTES test systems, a relay-specific configuration file is required. This file contains all information regarding the structure of the GOOSE message and its content. The ARTES 5 software analyses the configuration file and the desired signal can be selected. 

After the appropriate parameterization has been carried out, a GOOSE message can perform the same functions as the already used hardware inputs of the ARTES test systems.

Still questions? Then please use the comment function here in the blog or send an e-mail to bfleuth(at)kocos.com

Create ACI codecs yourself....

Enabling users to create their own codecs for their own needs was a requirement we placed on our latest ARTES innovation. The necessary basic knowledge of program development, especially in processing files, is already available to many users. Not much more is needed!

...or have it created by the specialist

Should the required skill be absent or short on time, KoCoS and its partners are ready to help. In cooperative collaboration, the required information and a sample file can be worked out by the user, and the KoCoS specialists will then take care of implementation. The codec created is then included in the standard so that it is available to all users.

Insight into the "secrets" of codec creation

As already described in the previous article, the ACI codec can be used to transfer any settings from an external file into the ARTES 5 software. ACI Codec is a collective term that summarizes different programs, the codecs. A codec is always adapted to a certain format of the source file. Since the source file can have any format, the complexity of the codec generally depends on its structure.


Since a codec maps the parameters of an output file to the parameters of ARTES 5, it is recommended to first define the links in the form of a table. Any necessary adjustments or conversions of the parameters to be read in can also be entered. These are then implemented in the codec itself.

Creation of an Empty Codec

A C#-project can be created automatically from within ARTES 5. This provides methods and properties on the basis of which the ARTES software can be parameterized. The structure of the created project automatically provides the possibility to read any file. 

Assignment of parameters

Since the concept of ACI-Codec is based on the principle of object-oriented programming, the basic structures of ARTES 5 could be mapped as far as possible by the methods and properties. This enables a similar procedure to be followed when creating a codec as when creating a test object in ARTES 5.
To show the basics of creating a codec, static values are assigned to a test object in the following example. For a mature codec, these must be replaced by variables and linked to values in the source file.  
As in ARTES 5, a new test object must first be created. Afterwards the parameters of the test object can be provided with the corresponding values. Depending on the integrated development environment (IDE) used, the Intellisense function simplifies this process considerably.

The created parameter is now assigned values for the "General Information" and "Rated and Limit Values". 

Elements such as functions and the characteristics they contain must be added to the test object in the software interface before values can be assigned, the same procedure is followed in a codec.

How it all began

As early as the beginning of the 1990s, KoCoS was able to offer products and solutions in the field of disturbance recording and switchgear testing which were unique in terms of their precision, functionality and simplicity of handling and operation. The basis for numerous innovations was a completely new hardware platform in 32-bit multiprocessor technology. 


DMSS - Digital Measurement Simulation System

For the research, development and product testing of these new device generations, a special signal generator was needed, which was not available due to the special requirements. In order to ensure compliance with the specifications and the quality of the products, a special signal generator, the Digital Measurement Simulation System DMSS, was developed. With this system, it was possible to generate any signal waveforms synthetically by using software and to output them as high-precision analogue values via the appropriate hardware.

At that time, the first digital protection relays were already in use. Their functionality also made great demands on the devices needed for testing. For the most part, conventional test equipment was still in use for relay testing, in which transformers were used to generate the signals. However, these devices were not sufficient for testing digital protection relays.

With the Digital Measurement Simulation System DMSS, KoCoS had developed a signal generator that could also serve as the ideal basis for a new generation of relay test systems. What was still missing were components for measuring analogue and binary quantities as well as current and voltage amplifiers to provide the test values with the necessary amplitude and power.


Ideas, innovations and a new standard

The decision was quickly made to develop a relay testing system. For the measurement part, there were already sufficient solutions available from earlier developments. So "only" powerful and precise current and voltage amplifiers were needed.

But before the development could really get started, a precise specification for the new system had to be created. Of course, we first looked at what the market had to offer specifically for testing digital relays. There was not a lot. In fact, very few, and it was therefore not difficult to find a lot of ideas for the new system. Talks with users in the field of secondary technology, with whom we already had contact from the fault recorder application, were certainly helpful here.

The most important requirement, however, was defined by the management. On the one hand, the new relay testing system should be significantly more powerful and cheaper than the products available on the market. On the other hand, it should have unique selling points and advantages that offer the user a high benefit.

In addition, the new system should also define the future standard for professional testing systems. Not an easy undertaking, but it was completely fulfilled with the introduction of the ARTES 440 25 years ago. The many innovations and special features that the first ARTES 440 already had to offer will be discussed in more detail in future articles about the ARTES USPs.


Lightweight and compact,

or bigger and heavier than expected?

At first glance, it seems that the ARTES RC3 is the little brother of the ARTES 460 because of the smaller number of inputs and outputs, just extremely robustly packed. It would therefore be expected that the RC3 would also be more compact and lighter than the ARTES 460. According to the specification, however, this is not so.

During the development of the ARTES RC3, high demands were placed on its robustness, reliability and durability. The basis for these requirements was already given with the 4th ARTES hardware generation. This has already proven itself in the ARTES 460/600 and is considered one of the most robust, if not the most robust hardware platform of all relay test systems on the market.

For the integration of the components into the RC3, a specially stable mechanical construction has also been developed inside a hard-shell case. Due to the construction and the robust and resistant hard-shell case, even hard shocks and vibrations have little effect on the RC3.

The dimensions and weight are higher for the first time.  In practice, however, this looks quite different. A relay test system is rarely used in the laboratory or in the workshop. Rather it is transported to the application site. And especially during the transportation the size and the weight are very important. Later during work the test system is moved rather less.

For safe transport, ARTES 460 is equipped with a robust transport box specially designed for this purpose. Inside the box there is a hard foam insert which fits the device and the cable set perfectly and which determines the external dimensions of the box.

Due to its construction in a robust hard-shell case, no additional transport box is required for the ARTES RC3. In comparison, it is a very compact and lightweight system which is very easy to handle in practice. This also makes the ARTES RC3 ideal for demanding outdoor use in rough environmental conditions. Larger and heavier than expected? Rather not.

Useful addition to the ARTES product line

With the ARTES 460 and ARTES 600, two very capable test systems are offered which provide almost all functions for protective relay testing. Where does the ARTES RC3 come in here and how does it differ from the other systems? 

ARTES RC3 has some features and advantages that are particularly useful for certain applications and target groups.


Renewable energy generation plants, especially wind turbines and solar parks, have become more and more important worldwide in recent years. In these plants there are special relays, such as the Q-V protection, which have to be checked regularly.

Energy suppliers and grid operators are often not in a position to comply with the tests due to the large number of installations and are often not the operators of these plants. The testing of protective relays is therefore more and more carried out by service companies.


The aim of developing the ARTES RC3 was to take into account the special requirements of these service providers or service companies. The new RC3 is also suitable for almost all other protection tests in the field of electrical power supply.

There are certainly some limitations due to the number of current amplifiers when testing differential protection relays. However, tests of frequency, voltage, overcurrent, distance protection and many other protection relays can be carried out just as well and efficiently with the ARTES RC3. In addition to the local operation, the new ARTES 5 software with all its special functions is also available for the RC3.


But what are the criteria that are especially important to service companies? Due to the number of test systems required, price is certainly a very important criterion for many customers. What they are looking for is a cost-effective solution that provides all the necessary functions but does not contain additional, expensive features that are not required for the specific application.

Another important point is the robustness of the device. The environment in which the tests are carried out often does not meet that of many conventional plants. Harsh environmental conditions are often encountered in regenerative energy generation plants. The high demands on robustness, reliability and durability were particularly taken into account in the development of the ARTES RC3. The RC3 is very well protected due to its design in an extremely robust hard-shell case.


And last but not least, the possibility of being able to carry out tests completely without a PC is often very useful for tests in regenerative energy generation plants. Even the test results of the RC3 can be read out via smartphone without a PC using the new ARTES app and clearly displayed in a test report. This report can also be sent by e-mail as a PDF file directly on site. 



The ARTES RC3 should therefore not be seen primarily as a replacement for the ARTES 460 or ARTES 600. Rather, it complements the product line in a meaningful way and offers exactly what a large customer base specifically needs.