Case Study: ARX Engineering achieves reliable automatic power transfer in Calgary high-rises with SEL protective relays

Automatic Transfer Scheme Retrofit Ensures Reliable Power in Calgary High-Rises

ARX Engineering, a Calgary-based electrical engineering firm serving commercial, utility, industrial, and institutional clients, faced a recurring challenge in high-rise buildings where aging transfer schemes failed to automatically restore power after utility disturbances. These outages disrupted building operations, forced evacuations, and created safety and liability risks for tenants and owners. To modernize these systems, ARX Engineering worked with Schweitzer Engineering Laboratories (SEL).

Schweitzer Engineering Laboratories (SEL) provided a retrofit automatic transfer scheme using SEL-351 directional overcurrent and reclosing relays and SEL-551C overcurrent/reclosing relays. The new microprocessor-based solution added automated, synchronized source transfer, remote alarm notification, overcurrent protection, event reporting, and better troubleshooting and monitoring. Installed at five Calgary facilities, the system eliminated malfunctions, improved reliability, and gave building owners confidence in alternate-source transfers while also alerting them when utility transfers occurred or the standby source had issues.

ARX Engineering

Roland Davidson

Operations Manager