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GSA OUTBRIEF 23
Submetering & Analytics: Single-Circuit Meter
If you missed our last Outbrief webinar #23, “Submetering & Analytics: Single-Circuit Meter,” a recording and presentation slides are now available.
Many thanks to all the presenters and to the participants for their thoughtful questions, some of which are answered here:
Q: What was it specifically that made the installation of these meters easier/faster? Anything beyond the box build?
A: Installation is streamlined by eliminating programming: the gateways automatically find the meters. For reference, the revenue-grade meters that were mounted alongside the single-circuit meters took 3 times as long to install.
Q: What happens when the internet is unavailable? Does the data continue to record locally on the gateway?
A: Yes—at least 2 months of data is stored on the gateway and is transmitted when the internet is available again. The meter stores 3 weeks of data.
Q: What is revenue-grade accuracy and do these meters match that accuracy?
A: The American National Standards Institute (ANSI) defines revenue-grade accuracy as +/- 2%. In general, the single-circuit meter matched that accuracy. The average error in energy measurement was <2%, except when chillers were online but idling. The manufacturer states that a new meter design combined with high accuracy CTs should mitigate measurement errors for low-power loads.
Q: What calibration schedule is recommended?
A: No calibration is necessary. However, it is important to right-size CTs and transformers.
Q: For high voltages (480V), can the CTs be installed without a shutdown?
A: Yes.
Q: It was mentioned that these submeters monitor lighting and plug loads. Can they also monitor receptacle loads, including Automatic Receptacle Controls per ASHRAE 90.1?
A: Submeters can monitor lighting and plug loads, though this was not part of the evaluation. The best-use case for the single-circuit meter is either a single large piece of equipment or a panel mains.
Q: Sometimes other devices, such as flow meters or temperature sensors, are required for measurement and verification of energy conservation measures. Can the same gateway transmit data from other devices?
A: The gateway can get data from other Zigbee devices, so, if 3rd-party devices use Zigbee protocol, they should be able to be integrated into the gateway.
Q: Can data such as power factors, frequencies, and reactive power be collected with these submeters?
A: Yes, the single-circuit meter measures current, voltage, power factor, frequency, power, and reactive power. It also measures harmonics up to the 45th order.
Q: Can the meters perform trending analysis and produce reports?
A: Analysis and trending reports are available through a software as a subscription service (SaaS). Data can also be integrated into GSALink.
Q: Is the Single-Circuit Submeter available for wider adoption and roll-out?
A: GPG evaluated the field performance of two single-circuit submeters, the Meazon DinRail ULTRA 3-Ph meter, and the Centrica Pan-42 meter. Researchers at the National Renewable Energy Laboratory found that both meters measured energy use with similar degrees of accuracy. For more information on these meters, please contact John Gionas, j.gionas@meazon.com or Stelios Koutroubinas, s.koutroubinas@meazon.com at Meazon and Laura Heon, laura.heon@centrica.com at Centrica.
Reference to any specific commercial product, process or service does not constitute or imply its endorsement, recommendation or favoring by the United States Government or any agency thereof.
Webinar Links
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Emerging Building Technologies’ two programs, GSA Proving Ground (GPG) and Pilot to Portfolio (P2P), enable GSA to make sound investment decisions in next-generation building technologies based on their real-world performance. www.gsa.gov/gpg
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