The answer is . Thousands of substations worldwide still run SIPROTEC 4 relays installed between 2005 and 2015. These relays are built to last 20+ years. Replacing a working SIPROTEC 4 relay with a new SIPROTEC 5 relay costs $5,000–$15,000 per unit plus engineering hours.
Once you obtain DIGSI 4.91, backup the installer and your license dongle in a fireproof safe. Finding this software again in 2028 will be even harder than it is today. Disclaimer: This article is for informational purposes. The author is not affiliated with Siemens AG. All trademarks are property of their respective owners. Always verify software licensing with your local Siemens representative. siemens digsi 4.91 download
If you have landed on this page searching for a "Siemens Digsi 4.91 download," you are likely an electrical engineer, a substation technician, or a maintenance specialist facing a specific challenge: You have an older SIPROTEC 4 relay (such as the 7SJ62, 7SJ64, 7UT61, or 7SA6 series) and need to interface with it. However, finding a legitimate, safe, and functional download link for legacy software is notoriously difficult. The answer is