KoCoS Blog

Timing measurements of AIS and GIS switchgear, what are the differences?

GIS high-voltage switchgears are located at many nodes in our voltage network, such as three-phase or single-phase encapsulated switchgear panels. High-voltage switchgears consist of several components and can be designed differently depending on the required function. They contain components such as current transformers, disconnectors, ground switches, circuit breakers, etc. Compared to air insulated switchgear (AIS), they offer a number of advantages, including smaller space requirement, higher personnel safety, a longer service life, and higher reliability. Disadvantages compared to AIS are evident in terms of maintenance, as individual components are very difficult to access. Measurements, such as those of circuit-breaker operating times and resistance of the circuit-breaker interrupter units, are rather difficult to carry out, since the basic requirement is that in high-voltage installations, all the parts being worked on must be grounded.

In outdoor switchgear systems (AIS), measurement with ground on both sides is generally not a major problem, simply because the typical ground resistance is much higher than the main contact resistance. KoCoS uses "Dynamic Timing" to combine the ACTAS switchgear test system with PROMET resistance meters.

The standards DIN VDE0105-100 and EN50110-1 clearly state that a GIS system must be measured with ground on both sides. The problem, which is particularly relevant for GIS, is the very low ground resistance resulting from the encapsulation of the entire switchgear in a metal housing. It often can be that the ground and housing resistance is lower than the main contact resistance. This makes it difficult to carry out a condition assessment of the switchgear using standard measuring equipment.

Use of the Kelvin test probes KP 200 together with PROMET R300/R600

The KP 200 Kelvin test probes were developed for safe and easy resistance measurement at measuring points which are difficult to access. The test probe pair is equipped with spring-loaded high-current and voltage contacts for the determination of low-resistance according to the four-wire method for a test current of up to 200 A.

 

Can the test probes be used together with the PROMET R300 or R600 resistance meters?

The PROMET R300/R600 are designed with 13 mm high current sockets for the connection of 50 or 70 mm² high current cables. With the reducers 13/9 from 13 mm to 9 mm socket/plug diameter, it is possible to connect high-current cables with a smaller cross-section and 9 mm plugs or sockets to the PROMET R300/R600, such as the CS 205 cable set (2 x 5 m , 25 mm²).
With these cables it is now possible to use the KP 200 Kelvin test probes with the PROMET R300 or R600.

 

Furthermore, a measuring mode for the safe use of the KP 200 Kelvin test probes has been implemented in the stand-alone operation of the PROMET R300/R600 (from firmware version FWP 1.5).
According to the maximum load of the KP 200 Kelvin test probes, the current output in this mode is limited to 200 A.

If the measurement has started actively, the measuring device waits in this measuring mode for the test probes to be placed on the test object. A measurement is only carried out when the test probes are reliably and completely contacted (voltage and current contact). That is, the test current is output, the best measuring ranges are determined and the resistance value is measured. The measurement is carried out automatically with the shortest possible measurement time.

In order to simplify the use of the test probes on site, the current status of a measurement is also signaled by means of the LED status display and an acoustic signal.
The measurement result now remains on the display until the test probes are removed and the next measurement process is activated by placing the test probes. The resistance measurement results are displayed in a table and the results can be viewed before they can be saved.

With this sophisticated functionality, safe and automated operation of the KP 200 Kelvin test probes together with the PROMET R300/R600 resistance measuring devices is possible.

If you have further questions, please leave a comment or contact us directly.

Share of renewable energy is constantly increasing

In Germany, the share of renewable energies in 2019 was about 43% of gross electricity consumption. In total, about 242.5 billion kWh of electricity were generated from renewable energy sources. 

The aim is to increase the share to 65% by 2030.

The rapid expansion of renewable energy sources in the electricity sector worldwide is definitely the right way forward. However, it also generates undesirable side effects. For example, the structure of the electricity grid, which has grown over decades, is in many parts not designed for decentralized power generation. Many sections of the grid are already operated at the limits of their capacity. The more the decentralized expansion progresses, the more demanding and more difficult it becomes to monitor and ensure Power Quality .

Factors that accelerate the expansion of PQ measurements

The increased demand for PQ measuring points is a direct consequence of the expansion of renewable energy sources and the associated changes to the basic architecture of power supply networks.

There is a continuous and increasing change from a centralized generation model to a decentralized model in order to be able to integrate more and more renewable energy sources - often in smaller power categories and in highly distributed design.

This new model fundamentally changes the characteristics and the electrical signatures flowing in the system.  A change that creates an increasing and urgent need for accurate measurements of power quality at more and more locations within the distribution network. These measurements are not only used to record and monitor quality parameters, but also to detect undesired interactions between network components, which often occur only under certain operating conditions and can lead to shutdowns, unstable operating conditions or a reduction in performance.  

The fundamental changes in our power generation and distribution systems make it necessary to take the monitoring of power quality and the complete recording of all network processes even more seriously in the future.

Conclusion

 

Our measurement systems of the EPPE and SHERLOG product line offer a reliable and robust platform and can be used on all voltage levels.

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.

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.