CITEL DLC-24D3 Ultra Slim (6mm) Din Rail Surge Protector for 4-20mA Current Loops Datasheet Contact Us Data Network: 4-20mA, 2W+SHIELD+G Application: Control Panel, Pump Panel, Power Cabinet, PLC In order to limit the effects of lightning or switching transients to acceptable levels for critical equipment and installations, the most effective solution is to install a protection device against these events. We call this an "SPD" (Surge Protective Device), they are deployed into the wireless network at the input to a distribution bus or directly at a sensitive load. The purpose is to harmlessly divert damaging surges away from your sensitive equipment before any disruption occurs.