Issue link: https://resources.mouser.com/i/1437732
23 littelfuse.com involved. In the following, we present an overview of circuit protection solutions that are particularly appropriate for various industrial automation applications and the advantages they provide for ensuring the reliability of the systems driving the factories of the future. Industrial Ethernet Industrial Ethernet (IE) combines standard Ethernet protocols with rugged connectors and high-temperature switches. Components used in industrial applications must be able to withstand temperature extremes, humidity, and vibration significantly beyond the ranges for equipment intended for installation in typical office environments. Industrial Ethernet networks must interoperate with existing and legacy systems and provide predictable performance and maintainability. In addition to physical compatibility and low-level transport protocols, a practical Industrial Ethernet system must also provide interoperability of higher levels of the Open Systems Interconnection (OSI) model. An industrial network must provide security both from intrusions from outside the plant and from inadvertent or unauthorized use. Figure 1 illustrates one approach to indoor long-haul data line (not PoE) protection against lightning-induced transients, ESD, EFT, CDE, and power faults that's appropriate for use in a factory automation environment. Some Industrial Ethernet circuit protection applications pose even greater challenges, such as in facilities with multiple buildings with equipment and cabling located outdoors. Figure 2 shows a circuit protection scheme optimized for these applications involving severe outdoor exposure in environments with frequent electrical storms. Figure 1: One approach to indoor long-haul Ethernet data line protection against lightning, ESD, EFT, CDE, and power faults. The four data lines shown (Tx± and Rx±) are protected against intra-building lightning transients. The LC03 TVS Diode Array diverts the majority of energy away from the transformer, but any common-mode energy that does get coupled across the transformer interwinding capacitance is diverted to GND by the SP3051 TVS Diode. This component can be connected to the ground on the PHY side of the transformer because the transformer itself meets the IEEE 802.3 isolation requirements. Figure 2: For applications that are subject to severe levels of lightning-induced transients that exceed the limits of today's silicon technology, gas discharge tubes (GDTs) are often recommended to protect the transformer. The GDTs are connected between the data pair (and not GND) to be compliant with the IEEE 802.3 standard. The SL0902A90SM GDTs shown here are used in addition to extremely robust protection components, such as two LC03 Series TVS Diode Arrays, to suppress the let-through energy at the PHY. The F1-F4 TeleLink fuses provide overcurrent protection against power faults.