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Testing of inrush-stabilization – quick and easy with ARTES

25. August 2022, bfleuth - Protection relay testing

When transformers are switched on, inrush currents can occur that exceed a multiple of the transformer rated current. Since the inrush current decay again after a few milliseconds, protection devices must separate these from fault currents and block tripping accordingly to ensure correct operation.

If the inrush current is analyzed with a suitable measuring device such as the SHERLOG fault recorder, an increased 2nd harmonic component can be detected. This increased proportion is also used by the protection devices to provide inrush stabilization. If the proportion of the 2nd harmonics exceeds a specified percentage, the trip is blocked by the protection device. 

Since this is a blocking of protection functions, the inrush stabilization testing has to be part of the protection testing. For this purpose, test quantities that are within the tripping range of the protection device have to be superimposed with corresponding proportions of harmonics and the reaction of the relay has to be evaluated. With the VD-Monitor of the ARTES 5 testing software, such test sequences can be created in a simple manner. The ratio between the fundamental signal and the superimposition can be kept constant or changed in steps by means of ramp definition. Thus, combining several test sequences with different settings enables phase-selective testing of the inrush stabilization in a single test routine.

 

Any questions or additions to the topic? Then please use the comment function here in the blog or send an email to bfleuth(at)kocos.com.

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Voltage transformer VT2

14. February 2022, bfleuth - Power source, Protection relay testing

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

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Relay testing with ARTES 5 - The testing software for all cases!

24. August 2021, bfleuth - Protection relay testing

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. 

Database

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

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GOOSE – What does the bird have to do with the protection relay testing?

29. April 2021, bfleuth - Protection relay testing

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. 

Configuration file opened with ARTES 5

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

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