Phoenix Contact 2800785 A surge protection system comprising a protective plug and base element, featuring an integrated multi-stage status indicator on the module for use with three signal wires sharing a common reference potential is suitable for high-frequency applications and telecommunications interfaces that operate without a supply voltage, supporting data transfer rates of up to 90 Mbps. This type of surge protection can be used in safety-critical circuits, providing a SIL 3 level of reliability.