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Köhl s.à.r.l. Power Distribution Systems, headquartered in Wecker, Luxembourg, belongs to the Köhl group of companies and is a manufacturer of state-of-the-art power distribution systems for the medium and low voltage levels, also specialising in sophisticated control systems. Since its founding in 1971, the Köhl Group has grown from a one-man electrical operation into an international technology corporation with locations in several countries. The goal of all companies in the Köhl Group is to push innovative technologies and execute complex projects like the one presented here.
“Our switchgear and systems are developed, planned and manufactured at locations in Germany and Luxembourg, and installed for customer projects in many areas around the world”, explains Michael Krämer, Director of Sales & Business Development at Köhl. “To this end, the focus is always on catering for the most demanding requirements in terms of system availability and safety du-ring electric operation.”
Köhl supplies the entire range of products for the gas treatment plant in the Caribbean island state off the coast of Venezuela, including medium voltage switchgear with corresponding protection and switchover devices, low voltage, main and sub-distribution systems plus associated peripheral components such as transformers and busbars. Denovo Energy, a subsidiary of Proman, headquartered in Switzerland, which also has a subsidiary in Trinidad was the prime contractor involved in the installation of a gas processing unit for the Trinidad facility. The gas extracted offshore is treated in a complex process and transported by pipeline to a methanol factory further inland. The methanol serves as the raw material for chemical processing.
The scope and complexity of the project, the necessary permanent availability and the extremely high level of safety in the petrochemical environment place severe demands on all stakeholders when it comes to the technical equipment. “Avoiding sources of error is an important prerequisite for ensuring high system availability”, explains Krämer, “and this applies not only to the petrochemical process itself, but also to the overall energy supply as the backbone of the process chain.”
Detecting electrical faults
In the low voltage network, circuit breakers and residual-current devices protect people and electrical equipment from the effects of faults. In the medium and high voltage ranges, current and voltage are measured indirectly using suitable protection transformers. A digital protective device compares the measured variables with individually configured protection parameters at millisecond intervals.
If a fault is detected in the grid, the protective device issues an OFF signal that triggers the switch-off coil of the circuit breaker. The faulty outlet of a defective motor, transformer or cable is thus reliably deactivated within the space of a few milliseconds in order to protect the surrounding systems. In the medium and high voltage ranges, such grids frequently branch out over several kilometres. In this context, it is important that electrical faults are detected, the fault location determined and the system reliably switched off via the nearest switch. High-performance digital protective devices are therefore used in both medium and high voltage grids.
Routine inspections and tests
Proper functioning of the digital protective devices is tested regularly as part of a protection test programme. The measuring signals from the current and voltage transformers to these devices are specified for this purpose using a special test device. The protection parameters set in the digital protective devices must be configured in accordance with the grid area to be protected and adjusted where necessary.
To ensure that the protective functions for the medium voltage transformers and switchgear of the gas processing unit could be tested for correct functioning, a high-performance plug-in system was specified as a key component of the project. The Fame test system is plugged into the protective test device and the wired Fame plug inserted into the test socket. “Only when the test plug is connected are all current transformers short-circuited and the trip signal for the line switch interrupted by the integrated forced switching sequence”, explains Alexander Stehle, the project manager responsible at Köhl. “You can then start the routine test cycle immediately in order to check the operative function of the protective device.” To this end, the display integrated in the test plug visualises the switching states and short-circuit functions to the test engineer. Several function shafts for plug-in bridges and bridge bars enable versatile use to accommodate all protection requirements.
Unlike with high voltage, spare protective devices are not typically installed in medium voltage applications. During the protection test, the outgoing energy circuit cannot be safeguarded by the protective devices being checked. “If a grid fault occurs during the protection test, serious injuries and damage to property or equipment can result”, Stehle affirms. “For such scenarios, the Fame 2 protective plug-in test system provides the option of looping in a parallel protective device via the additional test sockets.” This innovative technology allows operators to improve system availability considerably during the trip testing procedure.
Cooperative Fame configuration
Numerous innovations of the Fame 2 plug-in test system were showcased at the 2017 Hannover Messe. All requirements defined in the tender were fulfilled – particularly with regard to availability. “We can now configure Fame individually for the part of the plant to be protected”, reports Stehle enthusiastically. “We can thus switch up to 21 contacts with just one plug-in procedure.” The sequence for contacting, disconnecting and short-circuiting is specified by means of the freely configurable plug-in test system. Positively driven contacts prevent Fame from being used incorrectly.
The close collaboration between Stehle, the project manager at Köhl, and the application engineers at Phoenix Contact led to a solution being implemented that exactly matches the end customer’s requirements. The plug-in test system was also configured for the protection systems for both transformers, which convert the high voltage from the supply grid operator into medium voltage on site. In addition to the current and voltage transformers, several control contacts for the step switch and the trip contact of the circuit breaker are also managed via the plug-in test system. It is hence pos-sible, for example, to test the transformer and its auxiliary units such as the step switch with just a single Fame configuration.
“Thanks to clever details like the individual configuration of the test system and the overriding short-circuit protection, coupled with the detailed technical advice, Fame 2 is now our preferred plug-in test system over all other solutions”, explains Stehle. “For us, it’s the safest and most innovative plug-in test system currently available in the market.”
Further solutions in use
Fame 2 is just one of many solutions offered by Phoenix Contact that are used in this project. The LM-S lightning monitoring system was likewise chosen to meet high requirements. Connection technology, high-availability power supplies and industrial relays were also installed in the systems. Following the successful acceptance of the functional system by the end customer at Köhl s.à.r.l. Power Distribution Systems in Luxembourg, the power distribution systems were shipped to the Caribbean to commence productive operation.
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Author: Timo Beuth
Application Engineer,
Phoenix Contact
