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: 2021-09-28