CERN, near Geneva, is one of the world's most significant research institutions and the largest research center in particle physics. More than 2,000 permanent staff and over 10,000 guest scientists from 85 nations work on a variety of experiments in fundamental physical research, aiming to uncover the secrets of the structure of matter. The technical effort involved is as immense as the demands on the precision and durability of the devices used, and often, entirely new technologies and methods must be developed for the numerous experiments.
 

Unresolved Mystery of Nucleon Spin

One of these fundamental experiments, the COMPASS experiment (Common Muon Proton Apparatus for Structure and Spectroscopy), aims to study certain properties of the spin of protons and neutrons in an atomic nucleus that have not yet been fully understood. Spin refers to the intrinsic angular momentum of a particle, which, while analogous to mechanical angular momentum, can only take on specific values due to quantum physical effects and can also be non-zero for point-like particles. Protons and neutrons have a spin equal to half the reduced Planck constant. However, protons and neutrons are composed of gluons and quarks, which also have spin. Summing the spin values of the quarks does not yield the total spin of a proton – a discrepancy for which there is currently no solid explanation. Possible contributors include the orbital angular momentum of quarks, as well as the spin and orbital angular momentum of gluons.

To find an answer to these open questions, a working group at CERN is currently preparing the COMPASS experiment with significant effort. "In this experiment, we will bombard a cylindrical, approximately 120 cm long and 4 cm thick target of crystallized, deep-frozen ammonia with a beam of muons to investigate the spin structure of the proton through deep inelastic muon-proton scattering," explains Fabrice Gautheron, a nuclear physicist heavily involved in the conception and setup of the COMPASS experiment. "The particle beam used comes from the SPS accelerator (Super Proton Synchrotron), one of several accelerators at CERN, some of which are used for their own experiments or as injectors for the large, 27-kilometer LHC (Large Hadron Collider)."
 

Lowest Temperature at CERN

When the ammonia target is bombarded with muons, new particles such as pions and kaons are produced, which, along with the scattered muons, are analyzed in a downstream, approximately 15-meter-long spectrometer. For the data obtained to be meaningful, the normally randomly distributed spin of the nucleons in the target must be uniformly aligned. To achieve this, the target is exposed to microwave radiation at a frequency of about 70 gigahertz for twelve hours, while a strong magnetic field of 2.5 Tesla is simultaneously applied. This process stimulates spin flipping into a defined state, so that in about 80% of the ammonia molecules, the three free protons are uniformly aligned.

However, such strong magnetic fields require high currents, which can only be realized with superconducting coils. Therefore, the entire apparatus is cooled to 50 millikelvin – the lowest temperature used at CERN. A cryostat is used to achieve these extremely low temperatures with the help of liquid helium. The evaporated helium is fed back into CERN’s multi-kilometer-long pipeline, purified, and re-liquefied so that it can be used for further experiments.
 

A Precise Magnetic Field Enables the Experiment

To generate the required magnetic field, the test setup contains a solenoid in combination with a dipole. The solenoid, a cylindrical coil with 6,000 windings in 10 layers, produces a tubular longitudinal magnetic field. The ammonia target is placed at its center, while the dipole generates a magnetic field perpendicular to the solenoid. Solenoids, however, produce a magnetic field that weakens towards the ends. Since the strength of the magnetic field and the frequency of the microwave field must be precisely matched, and the target must be exposed to a constant magnetic field along its entire length, compensation for this field strength drop was necessary to ensure the entire target is polarized. This compensation is achieved by 16 smaller correction coils strategically positioned on the solenoid. The magnetic fields they generate do not need to be overly strong: while the solenoid is powered by a current of 650 amperes and the dipole by 590 amperes, the correction coils only require currents in the range of three amperes.
 

Maximum Reliability with Power Supplies from ET System electronic

For the power supply of the correction coils, a cabinet containing 16 separate power supplies developed and built by ET System electronic has been installed. These linearly regulated DC lab power supplies of the LAB/SL type operate without thyristor pre-regulation, have very low ripple, and offer fast regulation times of about 250 microseconds. They can be operated as constant current or constant voltage sources, feature various interfaces, and have built-in electronic loads, as well as protection against short circuits, overload, and overheating.

The most important criterion in selecting these power supplies was their high reliability. The COMPASS experiment is scheduled to run initially from mid-2014 to 2017, with possible extensions to 2020, and will provide data to around 220 physicists worldwide during its operation. "We absolutely cannot afford an interruption to the experiment due to a power supply failure," says Fabrice Gautheron. "Since we have been using eight of these power supplies without any issues since 2005, we know exactly how stable and reliable they are. That was the reason for us to order eight more units of this type from ET System electronic to ensure maximum reliability for our nucleon spin experiment." The Central Apparatus for the COMPASS Experiment

16 LAB/SL lab power supplies provide power to the correction coils

ABB STOTZ-KONTAKT GmbH, based in Heidelberg, develops, manufactures, and distributes products for the electrical equipment and automation of buildings, machines, and systems. The specialist in switching and control technology offers customers from industry and crafts a range of products including encapsulated and non-encapsulated switches, circuit breakers, and NH fuse-switch disconnectors in addition to installation devices and building systems. In its in-house development lab, twelve testers work on preparing new products for mass production and demonstrating to certification bodies that legal requirements are met and that the products comply with various international standards such as IEC, CSA, UL, and CCC.

"Our development lab is authorized to carry out these tests itself because we are UL accredited, and this enables us to also test and certify compliance with other standards," explains Simon Stephan from the switching technology lab. "Our lab is audited annually, during which testing performance, procedures, and technical equipment are inspected." For auditing, the lab must also have suitable current sources to test products like circuit breakers and overcurrent protection devices in compliance with standards. The performance and accuracy of the current sources play an important role, as high currents are sometimes needed to test the behavior of overcurrent relays, circuit breakers, motor protection switches, and thermal and electronic overcurrent relays under different loads.
 

Custom Device with Flexible Frequency Range

For these safety-critical testing tasks, ABB STOTZ-KONTAKT has been using a single-phase alternating current source of the EAC-S 9000 type from ET System electronic since 2013. The power supply specialist develops and manufactures AC and DC sources, laboratory power supplies, inverters, and electronic loads—and in addition to its standard product range, it offers custom modifications to meet very specific requirements. ABB STOTZ-KONTAKT had specific demands when searching for a suitable AC source. The device not only had to provide an accuracy of 0.2%, but also deliver currents up to 2000 amps and cover the frequency range between 50 and 400 Hz.

The 400-Hz technology is becoming increasingly important because, compared to the established 50-Hz technology, the same power can be transmitted using smaller transformers or converters, and the cross-section of cables can be smaller for the same power transmission. This weight and space savings is particularly important in aircraft construction. The advantages of higher-frequency power transmission are also increasingly being recognized in other fields, especially in railway and shipbuilding industries.
Overcurrent relays and motor protection switches in 400-Hz technology will be in greater demand in the future—a clear reason for ABB STOTZ-KONTAKT to expand its product portfolio in this segment and to acquire a suitable alternating current source for the corresponding tests and trials.
 

At their Black Forest location in Hornberg, ABB develops and manufactures components for motor protection and control, such as the motor controller UMC100.3. ABB is a globally leading technology company in the fields of electrification products, robotics and drives, industrial automation, and power grids. Working with a Black Forest View: ABB in Hornberg
 

The Motor Controller UMC100.3

The motor controller UMC100.3 is an intelligent motor management system designed to monitor large three-phase motors. The device combines functions such as motor protection, motor control, fault diagnostics, and fieldbus communication. The controllers can be used for single-phase and three-phase motors and for motor voltages up to 1000 V AC, handling rated currents from 0.24 A to 63 A. Thanks to its fieldbus interface, the motor controller can also be arranged in a decentralized manner. Powerful Technology: The UMC100.3

The motor current can be monitored via a control system, and with the digital inputs and outputs, the motor can also be switched on and off directly on-site—functions that are particularly interesting for larger industrial plants.
 

Fully Automated Testing Ensures High Quality

After assembly, the UMC100.3 series devices are thoroughly tested in an automated testing system. "We apply very strict quality standards and therefore subject each of our devices to an individual test, where we check all functions and parameters," says Florian Backfisch, who is responsible for equipment construction, maintenance, and servicing at ABB in Hornberg.

"Since we have specific testing requirements that we need to implement securely, our ABB experts in equipment construction have designed and built the testing system." The Automated Testing System at a Glance
 

Thorough Testing: The Functional Test

The devices are first subjected to a high-voltage test, where the insulation between different potential groups is checked. Then, through a software upload, the devices are equipped with the necessary intelligence. Next, in the third station, the functional test is conducted, where the device is connected to a PLC and subjected to various currents. In this test run, different measurement currents flow through the motor controller, which are controlled by the AC500 PLC at the AC source.

While the current source delivers the corresponding reference values, the PLC connected to the device under test monitors whether the device correctly measures the respective currents and responds appropriately when programmed limit values are exceeded. For example, it checks whether the controller shuts off correctly at certain threshold values and meets the prescribed switching times.
 

Custom Design: The Current Source

To provide the currents with the required stability and accuracy, ABB uses an AC source from ET System electronic. The company from Altlußheim is one of the leading suppliers of AC and DC sources, regenerative sources/sinks, laboratory power supplies, and electronic loads. In addition to its wide standard range, the company offers custom modifications for its devices, fulfilling even the most specific requirements for small quantities or single units. ABB in Hornberg took advantage of this expertise to meet its requirements. "We use numerous laboratory power supplies from ET System electronic's product range throughout our entire production and have been familiar with the high reliability of these devices for many years," says Florian Backfisch. "For the specific requirements in our automated testing system, we ordered a custom-made source from ET System electronic. This source provides all the required currents and is equipped with various inputs and outputs, as well as a converter that converts the RS232 interface signals to a fieldbus interface." The AC Source from ET System electronic

In the system, the three contact rods can be seen, which are inserted into the controller by a linear unit. In addition to the current source, the device also contains a three-phase voltage source that delivers up to 400 V AC. Currents and voltages can be phase-shifted against each other, and we use this to simulate phase failures to test whether our device under test also detects a phase failure."
 

AC500 PLCs Coordinate the Test Run

During the test runs, a PLC in the testing system communicates with the source via a serial interface to set the respective target values for currents and voltages. A second PLC, connected to the motor controllers via a fieldbus connection, reads the values measured by the device under test. The values from the source and the motor controller are compared, providing insights into whether the controller is working correctly. To check the tripping time, however, a current transformer is also used, which allows the current flow to be measured with high temporal resolution. For example, if the device is set to 10 A and suddenly ten times the current flows, the device must shut off within the predefined time. "A measurement transformer is used to precisely capture this time," explains Florian Backfisch. "This allows for real-time measurement." The Neutral Conductor of the AC Source is Routed Through a Current Transformer
 

Many Years of High Satisfaction

"We have had very good experiences with the AC source, as with all devices from ET System electronic," says Florian Backfisch. "In particular, the reliability of the AC source, which was specially developed for us and used in series production, has impressed us. The device works flawlessly, just like the other sources from ET System, which have been running reliably for many years. We are very satisfied and will continue to use sources from ET System for simulating AC and three-phase networks in the future."

A transmitter generates microwave pulses that are reflected by raindrops, with the reflections providing information about the density and size of the drops. In two product lines, Selex ES uses power sources of the LAB/SMS type, which handle the power supply for microwave generation and microwave amplification. This task places high demands on the devices, as the transmission pulses are very short. The power supply must deliver nearly maximum power in the shortest possible time, requiring excellent regulation quality. "The LAB/SMS series from ET System electronic already offers very good performance, but to ensure that the output voltage of a maximum of 800 V DC at up to 6.25 A remains sufficiently stable during our short transmission pulses, we needed additional modifications," says Thomas Breuer, product manager at Selex ES.

"In a very constructive and seamless collaboration, ET System optimized the regulation parameters for us and further shortened the rise time of the power supply. This allowed us to not only meet all technical requirements but also benefit from the fact that ET System devices are particularly compact and lightweight, giving us an additional advantage over other products on the market."
A weather radar system from Selex ES

With the GHP 456 Titan, Netzsch has developed an analysis instrument based on the so-called plate method. A material sample is clamped between an electrically heated and an unheated plate. The electrical power required to maintain a stable temperature in the heated plate provides a measure of the sample's thermal conductivity. For powering the four heaters in the device, specially adapted power supplies are used, which deliver up to 5 A at voltages up to 150 V DC. "For this task, we need reliable and precise power supplies, which is why we use one LAB/SL unit and three devices from the LAB/S series from ET System electronic," says Dipl.Ing. Georg Neumann, responsible for the design and development of the instruments. "Since we control the devices through special software, we wanted power supplies without front-panel controls to avoid any confusion for customers and to provide additional protection against operational errors. ET System electronic made these adjustments in the shortest possible time and has been supplying us with power supplies with front panels reduced to the essential power-on and adjustment options." GHP 456 Titan with four DC sources of the LAB/SL type

To conduct heating tests on switchgear assemblies, the company needed a reliable regulated power source that could deliver up to 250 A of alternating current across three phases in the frequency range of 45 to 150 Hz.

For multi-day heating tests, the devices had to be very reliable, and to protect the operating personnel, the voltage needed to remain below the typical voltage range for such devices, ideally within the extra-low voltage range.

Test technician Heiko Fischer found what he was looking for at ET System electronic: “During the first phone call, we were informed that customizing an AC source of the EAC-3S type to our specifications would be no problem. The corresponding offer for a device with an output voltage of 3x8 V AC at a current of up to 3x250 A was also more affordable than other suppliers, and during a company visit, we were very impressed by the competence and manufacturing quality at ET System electronic. The experience we have had with the devices since then has fully confirmed this positive impression, as evidenced by the fact that we have just placed an order for a third device.”

Images below: The ET System electronic devices in a rack from Hager

TE Connectivity is a global technology company that develops and manufactures a wide range of sophisticated connectors, sensors, and electronic components for use in devices, vehicles, aircraft, production facilities, and power plants. At its automotive site in Speyer, the company develops and produces connector systems and sensors for the automotive industry, focusing on applications for hybrid and electric vehicles, particularly the charging system. This includes all components from the grid connection point, such as charging cables with protective electronics, vehicle connectors, high-current inputs, and the connection to the charging controller, as well as the electronic peripherals around the vehicle batteries.
 

Not So Simple: The Charging Process

There are several ways to charge an electric vehicle. In most cases, the vehicle is connected to the cable of a dedicated charging station. These stations usually have their own power connection, are separately fused, and enable a relatively high charging current. Depending on the conditions, direct current (DC), three-phase current, or single-phase charging is possible at a charging station. Charging currents can be as high as 60 A for DC, 30 A for three-phase, and 10 to 15 A for single-phase charging. DC charging offers the advantage that the current does not need to be converted, allowing for higher currents. This can reduce charging times to as little as 20 minutes, while a standard three-phase charge takes at least 1 hour, and single-phase charging via a wall box typically takes at least 2 hours, depending on the allowable maximum current.
 

More Than Just a Few Wires: The Charging Cable

However, charging stations are not always available, so every electric vehicle comes with a charging cable, often referred to as an emergency or safety charging cable. This cable plugs into a standard household socket, but since other loads often share the same circuit and no communication between the house grid and the vehicle is possible, the charging current must be limited. The maximum continuous current is about 10 to 12 A, which leads to a charging time of up to 6 hours.

"Developing and producing such a charging cable is not a trivial task, as it needs to be usable in as many different countries as possible," explains Stefan Stross, Senior Manager Engineering for the Global Electronic Charger Cable. "Worldwide, a large number of different plug systems are used that are not compatible. Beyond the mechanical design differences, there are significant differences in power grids, not only in terms of voltage systems and grid frequencies but also in how the electrical ground is connected, the design of the return conductors, the phase relationships between the conductors, and whether one or two phases are connected." The global grid landscape is broad, and developing a universally usable cable is unrealistic. To enable at least regional use of charging cables, TE develops and produces different cables for use in Europe, North America, and Asia, covering all the variations in requirements encountered in these regions.
 

Ensuring Safety: The Integrated Monitoring Electronics

To monitor the charging process without a dedicated charging station, TE Connectivity engineers have integrated monitoring electronics into the cable's housing, known as an "in-cable current detection device." The charging cable (yellow) during a test

In the center, you can see the monitoring unit being inserted into a measurement computer. This electronic system is a protection and monitoring unit placed between the vehicle and the grid. It monitors current, voltage, and temperature, and includes features such as a thermal sensor in the plug to monitor the temperature at the socket. The electronics also check whether the vehicle chassis is live due to a short circuit or if there are fault currents due to connection errors or insulation defects. To disconnect the vehicle from the grid in an emergency, the monitoring unit includes contactors that switch the current on or off, ensuring the safety of both the user and the vehicle.
 

The Test Environment: Power Source and Load from ET System electronic

The monitoring electronics must function reliably under all weather conditions. They are therefore designed for a wide range of operating conditions and are initially tested in the lab before field tests are conducted with the vehicles. The test engineers at TE have set up a test bench where single-phase and two-phase systems can be simulated with the appropriate phase relationships and required voltages. A climate chamber also allows for testing the monitoring electronics under a wide range of environmental conditions—from the North Cape to the equator.

To supply the required currents and simulate the necessary loads with an electronic load, programmable power sources and loads are used. They are controlled by a master computer and can simulate various operating and fault conditions, such as short circuits. For the power source and loads, TE relies on proven technology: a modified version of the EAC-S 4000/Mod AC source

The cores are tested in-house by applying a primary and secondary test winding to a core. The primary winding is energized by a defined test current with a specific frequency, creating a magnetic field. This field flows through the core to the secondary winding, inducing a current that provides insight into the strength of the magnetic flux and thus the properties of the core. "For these tasks, we need a current-controlled AC source with an adjustable output frequency of up to 1 kHz, capable of delivering up to 20 A of current," says Managing Director Ewald Sorg. "We initially wanted to use an EAC-S 1000 AC source from ET System electronic, but the standard device, with its output voltage of up to 230 V AC, would have provided four times the total power required for our purposes. However, the complexity and cost of these devices are primarily dependent on power, so we requested a modified device that could deliver only the 45 V AC maximum voltage we needed. ET System electronic promptly offered us the corresponding modification, allowing us to stay within the appropriate power class. This way, we didn’t have to purchase unnecessary power, and this was significantly reflected in the price." Cut strip cores for coils and measuring transformers