KoCoS Blog

Filtered by category Power source Reset filter

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.

Modeling and generating power quality disturbances

Monitoring power quality (PQ) in the distribution system is an important task for energy suppliers and their customers. In a distribution system, various types of faults cause power quality disturbances. Power supply operation can be improved and maintained by systematically analyzing power quality disturbances.
The power supply is designed to operate with a sinusoidal voltage at a constant frequency. Power quality disturbances occur when the magnitude of the voltage, frequency, and/or waveform deviation change significantly due to various types of faults such as nonlinear loads, switching of loads, weather conditions, etc.
The effects of poor power quality depend on the duration, magnitude, and sensitivity of the connected equipment. Poor power quality can lead to process interruptions, loss of data, malfunction of computer-controlled equipment and overheating of electrical equipment.
It is important to detect and classify power quality disturbances. A variety of waveforms can be generated by simulations and be useful for disturbance detection and classification.
The waveforms of the possible disturbances are created in this description by mathematical models. The EPOS 360 three-phase signal generator and EPOS operating software are available for modeling and generating signals to analyze the events in the power system.

The mathematical models of the power quality signals can be implemented in the EPOS operating software by means of the "Signal Editor" module and generated with the EPOS 360 signal generator. The use of equations offers advantages as it is possible to vary signal parameters in a wide range and in a controlled way.
The following pictures show the different power quality signals which have been defined via the Signal Generator module.

Ideal voltage/current source
An ideal AC voltage source generates a continuous, smooth sinusoidal voltage.

Voltage fluctuations
A drop (undervoltage, voltage dips) or rise (overvoltage, swell) of the mains voltage of at least ½ cycle up to several seconds.

Voltage interruptions
A significant or complete voltage interruption. The interruption can be short-term but also permanent.
 

Harmonics
Distortion of voltage and current waveforms caused, for example, by operation of nonlinear loads.

Transients
A sudden disturbance in the line voltage that typically lasts less than one period and consequently the waveform becomes discontinuous.

In this description, the basis for generating typical power quality disturbances was presented. This signal generation solution includes the EPOS 360 signal generator supported by a PC with the EPOS operating software. The software includes the Signal Editor module, through which parameters such as amplitude, phase angle and frequency can be adjusted for signal generation. Furthermore, the Signal Editor module provides many other functions for adjusting the basic parameters, such as offsets, overlays and harmonics.
The hardware and software functionality makes it very easy to perform the generation of diverse waveforms. The generation of the previously defined waveforms is provided by four voltage and three current output channels of the EPOS 360. The signal generator can thus be used in procedures for testing instruments and devices for power quality measurement and analysis.

For more information, please refer to the following application notes:

  1. Signal generator EPOS 360 - A laboratory for power quality
  2. Three-phase signal generator for precise power network simulations

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

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

When testing electrical components, such as motors, accurate, reliable and powerful power supplies are required. Furthermore, in production, many processes are automated where time is an important factor in testing.

The voltage sources of the EPOS CV series are designed for above mentioned requirements, where adjustable output voltages up to 270 VAC / 300 VDC are needed.

A special feature of the EPOS CV voltage sources is the variable transformer with a fast motor drive that controls the AC/DC output voltage. A variable transformer is used because it enables a continuously adjustable voltage and is insensitive to current peaks. With the EPOS CV voltage sources, the output voltage can thus be steplessly adjusted to the respective requirements automatically and manually. 
The voltage sources are provided with internal voltage and current measurements via a controller, which significantly increases the efficiency of the system. The internal measurement electronics permanently control and regulate the values and ensure function monitoring. Among other things, the voltage sources are overload-protected with a circuit breaker that disconnects the output circuits in the event of a short circuit, for example. 
The series has been equipped with a convenient operating unit with touchscreen, jog wheel and function keys. The system is easy to operate and extremely user-friendly due to the control unit and display.
The output voltage can be set in stand-alone mode via the rotary knob. In automatic mode, the EPOS CV voltage sources can be easily integrated into own applications via an Ethernet interface.
The voltage sources of the EPOS CV series are available in different power classes. They are used wherever continuously adjustable DC and AC voltages in the range up to 270 VAC or 300 VDC are used. All models are suitable for connection in the frequency range 50 Hz / 60 Hz. 

Typical data of the motor-driven EPOS CV voltage sources are:

EPOS CV 821

  1. one phase
  2. 1 x 15..270 VAC
  3. 1 x 15..300 VDC
  4. 1 x 30 AAC
  5. 1 x 20 ADC
  6. 8,1 kVA

EPOS CV 831

  1. one phase
  2. 1 x 15..270 VAC
  3. 1 x 15..300 VDC
  4. 1 x 40 AAC
  5. 1 x 30 AAC
  6. 11,5 kVA

EPOS CV 753

  1. three phase
  2. 3 x 15..300 VACPN
  3. 3 x 15..520 VACPP
  4. 1 x 15..300 VDC
  5. 3 x 25 AAC
  6. 1 x 32 ADC
  7. 22,5 kVA

EPOS CV voltage sources provide both a high output voltage and a high output current. Especially when operating motors, large starting currents occur when the full rated voltage is applied, which can be many times the rated currents. The voltage sources are capable of supplying these current peaks up to 10 times the rated current of the load during the switch-on process.

Testing is the only way to ensure that electrical components function correctly. By analyzing the curve signatures of the actuating and operating currents and the resulting characteristics, it is possible to make accurate statements about the behavior of components and thus draw conclusions about their electrical and mechanical condition. For such analyses, KoCoS provides powerful AC/DC sources in the form of the EPOS CV series of voltage sources.

Would you like to find out more? You can find more information at the following link or contact us by mail at info(at)kocos.com.