Cable traysThe electromagnetic compatibility isCable tray manufacturersImportant issues of concern. Their research shows that cable trays are not only part of the grounding structure, but also a shielding structure for closed electronic systems. The key to this construction is the quality of the connection between the pallet components and the cabinet. However, it is important to note that the cable separation on the cable trough does not improve without a clear grounding structure.
Although the application of cable trays is mainly about mechanical and geometrical aspects to find the appropriate cable routing between different systems and devices, the electrical characteristics must be paid attention to from the perspective of electromagnetic compatibility. Schneider Electric's wibe has initiated work to address the differences in electromagnetic compatibility performance between different cable tray types and electrical connections between the mechanical components of the system.
A cable tray is a metal structure that supports cables, but does not contain electronics. In order to evaluate EMC performance, the entire system must be considered, including the electronic subsystems, interconnect cables, electronics enclosures, and metal trays surrounding the cables. Therefore, the cable tray can be considered as part of the shielded grounding structure to some extent, and its protective effect depends on the overall quality and good installation of the sub-components.
The EMC Directive of 2004 108 EC emphasizes the importance of installation quality for system performance, but there is less specific information on good engineering practices. However, modern literature and installation standards, such as EN 50174-2 and the EMMA manual, provide some technical recommendations and specifications. The purpose of these documents is to describe the effect of different installation qualities on electromagnetic compatibility.
In shielding and crosstalk performance tests for selected cable trays and their installations, the main objectives are to quantify the performance of the different cable tray systems and to evaluate the impact of poor and good installation of pallets and cabinets on the electromagnetic compatibility of the system.
Theoretically, cable trays are typically larger in size than most interfering wavelengths. If the interference wavelength is similar to or smaller than the size of the device, resonance may occur, reducing the electromagnetic compatibility characteristics. However, if the cable tray system is smaller, it is expected that the EMC characteristics can be improved. Therefore, the size of the cable tray system will have a direct impact on the EMC performance of the electrical or electronic system, especially in the low frequency range from 0 Hz to tens to 100 MHz. A wide range of disturbances can occur in this range, such as transients due to short circuits in the power system, leakage currents, switchgear leakage currents, power-frequency harmonics, lightning-related transients, RF radiation, and susceptibility.