Submeters and Analytics: Wireless Current Transformers (CTs)

Integrated sensors and analytics simplify submetering and reduce costs. Wireless CT sensors clip onto circuit-panel electric wires and draw power from them.

Researchers from the National Renewable Energy Laboratory (NREL) found that the easy-to-install technology could detect and diagnose faults.

View full-size infographic. [PDF - 388 KB]

GPG Findings 042, June 2019, SUBMETERS AND ANALYTICS: WIRELESS CURRENT TRANSFORMERS Opportunity: Why is GSA interested in submetering and analytics? TENANT OR EQUIPMENT-LEVEL BILLING, FAULT DETECTION & DIAGNOSTICS (FDD), ENERGY CONSERVATION MEASURES (ECMS) Technology: What are wireless current-transformers (CTs)? CLIP-ON SENSORS POWERED BY CURRENT IN ELECTRICAL WIRE No battery, meter, wiring or conduit required; data sent to the cloud Measurement and Verification: Where did Measurement and Verification occur? NATIONAL RENEWABLE ENERGY LABORATORY (NREL) assessed wireless CTs at the Cesar Chavez Memorial Building in Denver, Colorado. Technology was provided by Centrica. Results: How did wireless CTs perform in M&V? FDD ACTIONABLE Insights included short-cycling, on/off issues, and seasonal trends, 1 DAY INSTALLATION for 144 individual circuits in 13 panels and 4 HVAC equipment disconnects. Configuration software streamlined the process with real-time feedback, 7% AVG. ERROR IN MEASUREMENT up to 52% measured error for VAV loads with heavy cycling; not accurate enough for tenant billing, Accurately Tracks Load Profile Trends Precisely tracks on/off state of equipment, supporting FDD Deployment: Where does the study recommend deploying wireless CTs? FAULT DETECTION & DIAGNOSTICS Wireless CTs can monitor systems not typically captured by a building automation system and can be integrated into GSA’s smart building platform, GSALink. Pilot project is recommended to determine best practices, cost-benefit analysis and site selection. [PDF - 388 KB]


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Last Reviewed: 2022-05-06