KoCoS Blog

In our latest blog, we provide exciting insights into the use of our PROMET R600 micro-ohmmeter at the renowned company TRUMPF Laser-und Systemtechnik GmbH. Read how our micro-ohmmeter helps to minimize electrical losses and thus also ensures longer ranges for electric vehicles.

The requirement: Reduction of contact resistances

In e-mobility, systems and components must be one thing above all else: extremely efficient. Every kilometer counts and vehicles with a long range have the edge. Even the smallest components often have a major influence on this - such as copper contacts. These so-called busbars are often used in inverters and conduct the current from the battery to the drive, for example. They are usually screwed together. However, this reduces conductivity: a lot of energy is transferred via the contacts. The force-fit connection using a screw leads to a high contact resistance and therefore to power losses. To make matters worse, although copper is very conductive, it oxidizes quickly. The oxide layer on the surface also causes energy losses at the connection points. In electric vehicles, this affects the range, reduces performance and shortens the service life of the components. Reducing the contact resistance of billions of connections in e-vehicles worldwide offers enormous savings potential here.

The solution: Structuring the joint with a laser
TRUMPF takes this into account with a specially developed laser process. With its TruMicro7070 lasers, the Ditzingen-based company structures the copper busbars at the connection point before screwing them together. The laser removes any impurities and the old oxide layer and also creates a specific surface topography. The resulting new, pure oxide layer protects and preserves the condition of the surface in the long term. During screwing, the resulting structure leads to micro-deformations, resulting in a significant reduction in electrical losses - even over several screwing and unscrewing cycles.    
The laser removes the old oxide layer from the copper surface and ensures better conductivity at the screwed points thanks to the structuring.

The proof: measurement with the PROMET R600 micro-ohmmeter
The electrical conductivity can be determined by measuring the contact resistance. A lower resistance in the contact leads to lower electrical losses in the system and therefore also to a longer service life of the contact.

TRUMPF uses our high-precision micro-ohmmeter PROMET R600 for this measurement.

The PROMET R600 is a precision measuring device for determining resistances in the μΩ to mΩ range. Due to the measurement in four-wire technology and the output of high test currents up to 600 ADC, the resistance measuring device meets the highest accuracy requirements. The use of state-of-the-art power electronics and the robust design guarantee maximum reliability for stationary and mobile use in industrial environments such as at TRUMPF.

The contacts are evaluated both on the basis of the absolute measurement of the contact resistance and by measuring the so-called quality factor. The resistance in the contact is compared with the resistance in the homogeneous conductor.

By equipping the systems with three voltage measurement inputs, the resistances can be determined and compared in parallel at two measuring points at the same time. The quality factor K is calculated as the ratio of the resistance RCON of the connection over the overlap length lCON to the resistance RREF of the busbar of the same length lREF.

The result allows a direct comparison of different qualities of electrical transitions.

Copper contacts can be structured quickly and efficiently using laser technology. The result is a significantly reduced contact resistance, which is activated when the two metal components are screwed together. The KoCoS precision resistance meters PROMET R300/R600 are an ideal tool for characterizing such connections for high current and low resistance due to their measurement in four-wire technology and the ability to accurately measure both current and voltage.

Information on Trumpf's laser process can be found in the white paper "Laser structuring of copper busbars" at https://www.trumpf.com/de_DE/loesungen/branchen/automobil/e-mobility/laserschweissen-von-leistungselektronik/

Do you have any questions or additions regarding resistance measurement or our measuring devices? Then contact us via the comment function here in the blog or by email to info(at)kocos.com.

Compact motor and coil testing system for switchgear testing

KoCoS Messtechnik AG now offers the compact, portable EPOS MC4 test system for the supply, testing and analysis of motors and trip coils of switching devices.
In addition to its use as a powerful AC/DC source, EPOS MC4 records the operating currents of spring tensioning and pump motors as well as release coils and displays the motor and coil currents as numerical results on a 5" touchscreen.

The voltage source is based on state-of-the-art power electronics and is insensitive to interference in the power supply due to the synthetic generation of the output variables. Test sequences can therefore always be carried out under the same conditions, which enables a direct comparison of the results.

The EPOS MC4 can be operated and controlled via the integrated operating unit with high-resolution, resistive 5" touchscreen, rotary selector switch and function keys or in combination with the ACTAS test systems. EPOS MC4 can be conveniently integrated into switchgear tests via the ACTAS test software. A remote control unit is also available for controlling motor and coil outputs.

EPOS MC4 provides additional functions for analyzing switchgear:

  1. Analysis of motor running and coil tripping
  2. Determination of the coil resistance
  3. Determination of the minimum tripping voltage
  4. Testing undervoltage releases

The evaluation of the results is simple and conclusions about the condition of coils, motors and mechanics can be drawn immediately. The integrated measuring functions therefore guarantee meaningful analyses for maximum operating times and minimum maintenance effort.

EPOS MC4 enables the direct connection of a PC/notebook. The measurement results stored in the device can be read out and managed using easy-to-use software.

The test system is housed in a handy, extremely robust and hard-wearing hard case. Waterproof and dustproof to IP67 when closed, the case absorbs even hard knocks without sustaining damage. The robust test system is just as suitable for demanding outdoor use as it is for use in production or in the laboratory.

A special feature of the EPOS 360 three-phase signal generator is the operating unit for on-site operation. All basic operating and parameterization tasks, such as changing amplitude, phase angle or frequency, can be performed via the operating unit with touch screen, function keys and jog wheel. In addition, information about system states and an overview of the set signal values are displayed.

The jog wheel enables fast and precise changes of values and is used for setting as well as for controlling the device. The integrated illuminated ring provides a clearly visible display of the system states, acoustic signals provide additional information and feedback during settings and output.

The states and the operating modes of the inputs and outputs of the EPOS 360 are further signaled by numerous LEDs in the front panel. A quick glance is enough to see which outputs are active and which states are present at the binary inputs and outputs.

The function keys are used, among other things, to start/stop tests and to accept settings as well as to confirm memory prompts.

The VD-Static and Symmetric monitors are available for local operation. Amplitude, phase and frequency can be set independently. The output can be started directly and the signals can be changed stepwise during the output.

The function of changing the output values in specified step sizes allows simultaneously increasing or decreasing the values for voltage, current, frequency and angle in one step via the jog wheel.

The settings for a symmetrical three-phase system are to be made via the Symmetric monitor. For example, when setting the voltage value, the setting for all three voltage phases is adopted.

In the VD-Static monitor the settings for an unbalanced three-phase system are to be made. In this monitor the parameters for each phase are to be set independently.

It is possible to choose between different views for the monitors. The numerical view NUM gives an overview of the parameters and states of the outputs. In the VD view, the signals are displayed in a vector diagram. The right status bar shows the current status of all binary inputs and outputs.

The control of the output of the voltage and current amplifiers can be done in static or dynamic mode. In static mode, changes to the output values are only accepted and output after confirmation.

In dynamic mode, changes are accepted immediately. Thus, dynamic adjustment of the output values is possible without having to confirm them beforehand.

In addition, it is possible to store up to ten individual parameter sets for each output mode, giving the user the option of easily accessing predefined values.

With the high-resolution 5" touchscreen with Smart-Touch technology, function keys and a ergonomic jog wheel, three-phase signals can be output quickly and easily with the EPOS 360 signal generator, even without connecting an external PC. The clear user interface guides the user intuitively to the target.

Do you have any questions about our measuring devices?

Then contact us via phone +49 5631 95960 or by mail to info(at)kocos.com.

For many years, KoCoS has been recognized as the world's leading manufacturer of switchgear test systems. With the new ACTAS P260+ and ACTAS P360+ switchgear test systems, KoCoS now offers two portable devices which once again overtop the previous series in terms of performance.

  1. Larger range of functions thanks to new hardware and software features
  2. Increased flexibility in switchgear testing
  3. Improved ergonomics, functionality and performance
  4. Operation via integrated operating unit with 7" touch screen and/or the specially developed test software
  5. Easy operation with optimal display of all information
  6. Built in an extremely robust and compact case housing

ACTAS P360+ has been extended by two controllable outputs in the form of relays, which can be easily integrated into the test sequence. This also works retroactively with existing test templates from the pre-production series. ACTAS P260+ also received two additional control outputs, one also in the form of a relay, the other as an IGBT control output. For example, the reserve output coil of a switchgear can be connected directly without reconnection, which enables the connection of one input and two output coils simultaneously. The systems offer another major advantage with the display of measurement data oversampled at 200 kHz at 50 kHz.

There is also news in the testing software. ACTAS EXPERT is now generally included in the scope of delivery and offers some additional functions. Among other things, it is possible to export measurement data in various formats, to overlay measurement data using the measurement history and compare them directly, or to insert envelopes as a reference. For the display and analysis of the data, you can also create your own display graphics, which are also used in the corresponding test reports.

Do you have any questions, additions to the topic or would you like to convince yourself of the performance of the systems during a product demonstration online or in person at your premises? Then feel free to contact us via the comment function here in the blog or by e-mail to cstuden(at)kocos.com.

Gas has been getting more and more expensive for a year now, and the price of electricity in Europe is also rising significantly. Are these prices related and what role does which power plant play in this?

Gas shortage. Why is the price of electricity rising at all?
Since in Germany, as in the rest of the world, electricity is mainly generated by fossil fuels, the price of a kilowatt-hour naturally depends on the basic price of gas, coal, oil and, to a certain extent, uranium. If the prices of fossil energy sources rise, the price of electricity also rises.

How have energy prices developed so far?
Concerns about a shortage of gas supplies from Russia have driven gas prices ever higher, and not only in Germany. Power plants paid almost 227.0 percent more for natural gas in June 2022 than in the previous year. The gas bills of many end consumers have tripled. Alongside these rapid increases in prices in the gas market, electricity prices have also risen at the same time. Within one year, for example, the price of electricity on the Leipzig European Power Exchange (EEX) has increased 10-fold (as of August 2022) - from 50 to 565 euros per MWh. Of course, this also has a knock-on effect on consumers: the electricity price for new contracts in mid-November 2022, for a consumption of 4,000 kWh incl. basic fee, was 0.427 euros per kWh - and the trend is uncertain.

And what about electricity from renewable energies?
Electricity from renewable energies is by far the cheapest way to generate electricity. Once wind or solar power plants are built, they consume almost no resources for direct electricity production. However, they do not supply electricity continuously. This means that although energy from these sources is cheap, it is not constantly available everywhere without large storage facilities and well-developed electricity grids. Does the price of electricity fall when more electricity is fed into the grid from renewable sources? No, unfortunately it is not that simple. This is because the electricity market works according to the "merit order" principle.

Definition: Merit order
The merit order is the order in which power plants are deployed, which is determined by the variable electricity production costs. The cheapest power plants are switched on first to meet demand, and the last power plant with the highest marginal costs needed to meet demand determines the price. The merit order thus determines the electricity price on the energy markets.

In a simplified way, this means: All power plants offer their production capacities until enough electricity is produced in Europe to cover demand. However, no distinction is made in the type of generation: All suppliers receive the same price, determined by the most expensive power plant on the grid. In the merit order principle, for example, it does not matter at all how cheaply the renewable electricity was generated. Subsidies for the expansion of renewable energies do not count either.
Thus, at present, a single gas-fired power plant on the grid is enough to greatly increase the price of a kilowatt hour of electricity, regardless of the low costs of other energy sources or "power plants" at that time.

So why is there a "merit order"?
In a conventional market, supply and demand would determine the price - until the time when a product is no longer available. As a result, however, gas-fired power plants would then almost never be in operation, as cost-covering operation is not guaranteed. The "merit order" balances this out so that there is always enough electricity available to meet demand and the grids remain stable.
Each producer offers its electricity in such a way that its costs (marginal costs) are covered. All offers are then successively made until demand is covered - the most expensive power plant used then determines the price for everyone. This power plant only covers its marginal costs, all others make profits. The resulting price is called the marginal price.
Marginal costs are the costs incurred to produce the next commodity or, in this case, the next megawatt hour. Investment or capital costs are not included, but fuel costs, for example, are.
On the energy market, it generally applies that the "product" electricity must not be "sold out", as otherwise the energy supply can be disrupted and, in the worst case, a local or area-wide blackout could occur.

Who invented the merit order principle?
"The marginal price (found through the merit order) is not an artificial rule that someone made up," Lion Hirth elaborates in the Stuttgarter Zeitung. Lion Hirth is junior professor for energy policy at the private Hertie School in Berlin and managing director of the energy consulting company Neon. "It is not an arbitrary choice between alternative market designs, but the natural way prices form in free markets," he continues. Other commodity markets also function according to this principle - "no matter whether it is oil, gas, copper, milk or solar plants", says the energy expert.

What is happening at the moment?
Currently, several developments are coming together: Firstly, about half of the 56 nuclear power plants in France are currently out of operation due to maintenance work or technical defects. Secondly, the low water level of the rivers is hampering the supply of coal to the coal-fired power plants. And thirdly, the gas price is at a high level and, as described above, influences the electricity production costs.

Will coal, nuclear power and renewable energies not suffice?
Unfortunately not. On the one hand, this is because the current capacities of hydropower, wind power and photovoltaics are not sufficient to cover the entire electricity demand, neither in Germany nor in Europe as a whole. In addition, as described above, many conventional power plants are currently shut down or can only be operated to a limited extent.
Furthermore, there is a lack of transmission grid capacities across Europe. Often, for example, the electricity generated on the windy North Sea coast in Germany cannot be transported to the energy-hungry south of Germany. The Federal Network Agency reacts to such a bottleneck with a "Redispatch": the output of wind turbines is reduced in the north and the output demand of the power plants is increased in the south so that an overload of the electricity grid is avoided. Gas-fired power plants, which can adapt their electricity production particularly flexibly and quickly, are often used here. Of course, this also has additional effects on the electricity price.

Opportunities for action and risks
The increased gas price, mainly caused by the war in Ukraine, is also driving up electricity prices. Since electricity is included in the prices of many other products, including breakfast rolls, this is fuelling inflation. For weeks, there have been many discussions on how the price increase could be stopped.
"A discussion about redistributing profits and relieving the burden on consumers, but maintaining savings incentives, i.e. not a simple price cap, is in my opinion the way to go in the short term," says Christoph Maurer, Managing Director of the Aachen-based energy consulting firm Consentec. However, a fundamental change in the market design should definitely not be decided in the short term, he warns. "The risk of then arriving at solutions that have not been thought through and possibly even intensifying the crisis is very high" Maurer, an energy expert, told the Stuttgarter Zeitung.

References: The magazines: "Zeit, Standard and Stuttgarter Zeitung", the technical magazine "Chip", Wikipedia and own research.