Are the IP addresses of relay protection devices fixed

The IP addresses of relay protection devices are not necessarily fixed; they can be configured as static or dynamically assigned depending on the network setup and operational requirements.Static vs Dynamic IP AssignmentModern protective relays, especially those compliant with IEC 61850, are typically connected to substation LANs and can have static IP addresses assigned during commissioning for reliable communication and integration with SCADA systems, data historians, and other monitoring tools . Static IPs ensure that each relay can be consistently identified on the network, which is critical for protection schemes that rely on precise device addressing. However, in some installations, dynamic IP assignment via DHCP may be used temporarily during testing or for devices that do not perform critical protective functions over the LAN . Dynamic assignment is less common in operational networks because it can introduce uncertainty in device identification and complicate relay coordination and cybersecurity management.Reconfiguration and Cybersecurity ConsiderationsIP addresses can be changed during relay re-commissioning or when network configurations are updated. This may occur when passwords are updated, devices are replaced, or network topology changes . Any change in IP addresses must be carefully managed because it can affect communication with SCADA systems, DNP polling, and other automation functions. Proper documentation and coordination among protection engineers, automation engineers, and cybersecurity personnel are essential to maintain system reliability and security .Practical ImplicationsCritical relays that perform protective functions over a LAN usually have fixed IP addresses to ensure predictable communication.Non-critical or monitoring-only devices may use dynamic IPs temporarily, but static assignment is preferred for long-term operation.Network security requires that IP addresses, along with authentication and encryption measures, are managed to prevent unauthorized access or interference . In summary, while relay protection devices can have fixed IP addresses, the actual assignment depends on the network design, operational requirements, and cybersecurity policies. Static IPs are standard for critical protection devices, whereas dynamic assignment may be used in limited or temporary scenarios.