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Automation in the field of low-resistance measurement is increasingly required in the factory or laboratory. Be it in the automotive/electromobility sector, in the investigation of soldered or welded joints of high-current connections or in a wide variety of other applications.

For special requirements, e.g. for use in test stands, the easy-to-use PROMET PI programming interface is available for control and measurement with the PROMET R300/R600 resistance measuring devices. This can be used in COM/ActiveX-supporting as well as in .NET environments.
By programming the measurement sequence once, it is possible to integrate the PROMET R300 or R600 resistance measuring instruments into the test equipment via the programming interface and to perform measurements automatically.

A driver is installed with the programming interface, via which the connected devices are addressed. Communication between the software/PC and the external PROMET R300/R600 is made possible by the installed ActiveX component. This allows communication via USB or Ethernet interfaces.
As an example, an Excel sheet is used to control the PROMET R300/R600 and to evaluate the measurement results in this description, via which the programmed VBA macros (Visual Basic for Applications) are executed. Programs can be modified and adapted according to the requirements.

The PROMET R300/R600 precision resistance meters are an ideal tool for characterizing components for high current and low resistance due to their four-wire measurement and ability to accurately measure both current and voltage. 
As demonstrated in the article, a resistance measurement system controlled via external software can be easily integrated into an automated application. Using the PROMET R300/R600 resistance measuring instruments to perform such measurements simplifies the test setup, reduces programming time, and enables efficient test sequences.

Further information on the use of the PROMET PI programming interface can be found in the application report PROMET R300/R600 - The intelligent way to measure resistance!

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

Postscript
The EPOS 360 three-phase signal generator can also be integrated into your own test applications in a similar form via the EPOS PI programming interface!

Redispatch 2.0

Electricity network operators are required by the Energy Industry Act to ensure the security and reliability of the electricity supply in their network.

Redispatch refers to interventions in the generation output of power plants in order to protect line sections of the electricity network from overload and avoid bottlenecks. If there is a threat of congestion, certain power plants are instructed to reduce their feed-in capacity. At the same time, other power plants must increase their feed-in capacity. This balance-neutral control creates a load flow that counteracts the bottleneck.

Due to the steady growth of renewable energies, whose feed-in capacity is also largely determined by the weather and is subject to strong fluctuations during the course of the day, grid operators have to carry out redispatch measures more and more frequently. 

Previously, redispatch was only carried out with conventional large-scale power plants of 10 MW or more.

With the new Redispatch 2.0, all generation plants with a generation capacity of 100 kW or more, as well as smaller plants that can already be remotely controlled by the grid operator, will also be included in this control process on a mandatory basis. This also includes many decentralized CHP, wind and photovoltaic plants. 

The aim is to increasingly use even more accurate forecast data for predictive grid control in order to ensure grid stability and avoid bottlenecks. In addition, decentralized EEG plants are often located closer to the bottleneck to be resolved and can therefore be deployed in a more targeted manner. This reduces the control services required from large power plants and helps to lower costs in the overall system.  

When Redispatch 2.0 comes into force on 01.10.2021, operators of affected generation plants will be obliged to regularly provide comprehensive data to the grid operator. This includes, among other things, the live measurement data of the plant, which the grid operator can use to determine the power reserve available to it on the basis of the average power value of the past 15 minutes and use it for redispatch. This data is also used to determine possible compensation payments. 

But it is not only the power data that is of interest here. The applicable technical connection rules for power generation plants in medium and high-voltage networks VDE-AR-N 4110 and VDE-AR-N 4120 additionally prescribe the monitoring of voltage quality according to EN 50160 Class A as well as the high-resolution recording of network disturbances.

The measuring systems of the EPPE and SHERLOG product lines fully meet the requirements. Permanent power quality measurements, transient disturbance recordings as well as real-time measurement data transmission and visualization are performed in parallel and independently on these systems.  

Voltages and currents are recorded with a temporal resolution of 200 kHz and a measurement deviation of maximum 0.05%. The resulting data is stored fail-safe in a 32 GB ring buffer and transmitted via cable or LTE/G5-based network connection or can be read out directly at the device via USB interface. The remote data transmission can be time or event controlled. Thus, for example, a detailed fault report including the fault type, fault duration, maximum values that occurred, fault impedance and fault location can be automatically generated by the associated Expert software just a few seconds after a fault occurs and sent to operations management, e.g. by e-mail. Voltage quality reports can also be generated automatically and stored as PDF reports. Real-time measurement data can be read out via MODBUS or IEC 61850, for example, and visualized on all common browsers and platforms via the integrated web server.

LOTOS LT is a flexibly applicable standard measuring system and extremely cost efficient.
It is suitable for a wide range of applications in the automotive industry, in the field of medical technology, in the plastics and packaging industry, and also for fully automated testing of construction and insulation materials.

It has a height-adjustable operating touch screen and an integrated evaluation unit. Thanks to the small footprint, this standard module is extremely space-saving. The integrated evaluation unit ensures fast and fully automatic measurement evaluations. Inside, the LOTOS LC has various connection options to extend it with peripherals such as code readers. The stand-alone device is suitable for use in a production environment as well as in laboratory or measuring room.

Test parts can be measured at extremely high speed for 2D dimensional tolerances, as well as completely in 3D.

Example of measuring insulation materials:

Video of a measurement run:
https://cloud.kocos.com/index.php/s/XWz6Bg3WG2iyA6S

Graphical measurement results:

Saving of working time through simultaneous resistance determination at three measuring points

For switchgear in the medium-voltage and high-voltage level, the switchgear standard IEC 62271-1 requires a static resistance measurement of the main circuit in order to exclude an unacceptable heating of the current path.

Traditionally, the measurements are carried out one after the other and individually at each phase. The main circuit is supplied with 100 A direct current and the voltage drop is measured. If the measured value, i.e. the voltage drop is within the specified limits, the test is passed and the results can be recorded/stored. This measuring procedure is time-consuming as the three phases are tested one after the other.

To increase productivity and improve reliability, the measuring method for resistance and voltage drop measurement can be optimized with the PROMET R300 or R600.

The PROMET R300/R600 resistance measurement systems are equipped with three voltage measurement inputs, allowing parallel measurement at three measuring points, for example to measure the resistance of three main contacts statically.

 

In order to perform a simultaneous measurement of three main contacts, the test objects must be connected in series and provided with a test current connection. Since a four-wire measurement is carried out, it is important to ensure that the voltage connections are between the high current connections and that they are connected exactly at the points where the resistance is to be determined.

Connection example for a measurement on three test objects connected in series, e.g. three interrupter units.

In stand-alone mode, the three static resistance results with the measurement details (actual test current and voltage drop, measurement ranges etc.) can be stored in the measurement device.

 

The data stored in the device can be read out and managed with an easy-to-use PROMET software. The clearly displayed measurement results can also be output in a PDF test report or exported as CSV data.

The described simultaneous measuring method for the acquisition of three resistances thus saves working, changeover and measuring time!

As a further automation option, PROMET R300/R600 are equipped with interfaces for connection to the ACTAS 2.60 switchgear testing software. Resistance measurement can be conveniently integrated via the ACTAS test software. Even without an additional ACTAS test system, automated test sequences and a comprehensive analysis of the test results can be carried out without any problems.

 

The method is not only applicable in switchgear testing, but also in applications such as e.g. in the field of e-mobility, where several resistors have to be detected at the same time.

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

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.