Your questions answered: Benefits of powerful embedded metering at the source of consumption

The Oct. 5, 2017, “Benefits of powerful embedded metering at the source of consumption” webcast presenters addressed questions not covered during the live event.


Energy management is a growing practice among large and medium size companies. Successful energy management requires detailed information on how the energy is being used. However, this information is not available in facilities that are not actively being monitored. For proper energy management, it is necessary for facility managers to understand how and where energy is being consumed.

Energy efficiency is the first step in achieving sustainability in buildings and helps to control increasing energy costs while reducing environmental footprints. Energy management system can provide metering, submetering, and monitoring functions that allow facility managers to gather data that allows them to make more informed decisions about energy use.

The presentation will provide a general overview of the submetering and integration capabilities with standalone, energy management, and cloud solutions. Discussions around unique “embedded” solutions will allow consulting and specifying engineers to understand the benefits of an integrated SEM3 solution compared to traditional monitoring.

Presenters Robert Martin, business development professional, Siemens; George Roscoe, product manager, Siemens; and Bala Marimuthu, product manager, Siemens, responded to questions not answered during the live Benefits of powerful embedded metering at the source of consumption webcast on Oct. 5, 2017.

Question: How would you best integrate metering on a supervisory control and data acquisition (SCADA) system based on IEC 61850-2017: Communication networks and systems for power utility automation?

Answer: IEC 61850 is a standard protocol for vendor-agnostic engineering of the configuration of intelligent electronic devices for electrical substation automation systems to be able to communicate with each other. Siemens does have power meters with native IEC 61850 protocol for integrating with systems such as SCADA based on IEC 61850.

Q: How do you ensure meters are integrated into the building automation system (BAS) and/or electrical power monitoring systems?

A: Ensure that the meters have native BACnet IP or BACnet MSTP protocol available for BAS integrations. Ensure that the meters have native Modbus TCP/IP or Modbus RTU protocols available for EPMS system integrations. Siemens SEM3 has both Modbus and BACnet protocol options available for different system integrations.

Q: How best do we do the metering and what devices are available to do this?

A: Siemens power meters and power quality meters meets the ANSI and IEC standards. Siemens has a variety of basic meters and advanced power quality meters for different applications. Please contact us at this link for further request on this topic.

Q: Please discuss submetering accuracy requirements and regulations.

A: In the U.S., revenue-grade submetering accuracy is ±1%. There are ANSI standards available to meet the accuracy. ANSI C12.20-2015: American National Standard for Electricity Meters established the physical aspects and performance criteria for a meter's accuracy class. It supersedes certain details in ANSI C12.1-2014: American National Standard for Electric Meters - Code for Electricity Metering and ANSI C12.10-2011: American National Standard for Physical Aspects of Watthour Meters-Safety Standard.

The existing ANSI accuracy classes for electric meters are:

·         Class 0.5 - having ± 0.5% accuracy.


·         Class 0.2 - having ± 0.2% accuracy.


There are many regulation examples available:

·         NY PSC (New York Public Service Commission) certified meters: If the customer uses the submetering energy data to sub bill the tenants in the state of New York, then the meter must be certified by the New York Public Service Commission.


·         CA Weights & Measures Certified Meters (CDFA- California Department of Food and Agriculture - Division of Weights and Measures): If the customer uses the submetering energy data to sub bill the tenants in the Los Angeles county area, then the meter must be certified by CDFA.


·         Nationally recognized test lab (NRTL) certified meters: Most of the metering products in the industry goes through self-certification testing processes, which may be sufficient to get UL approval/certification. Many companies in the metering market take shortcuts. But only very few metering products in the industry go through very stringent testing processes to pass certain standards using the external NRTL.


·         Siemens SEM3 system meets all the above standards and passed through NRTL.


Q: Are embedded meters available for domestic (home) use at 120 V single-phase 20-amp supply?

A: Yes, the Siemens SEM3 system can measure 120 V single-phase circuits with a 20-amp supply. SEM3 measuring data is very accurate even when the load is very low, which is 1% of the amperage size.

Q: How does the SEM 3 system provide the corresponding potential sources for metering, especially when you might have mixed circuits such as 208Y/120 V and 480Y/277 V?

A: SEM3 can connect directly to a 480 V system and it is a single voltage and multiple current source system. Not used for mixed voltage inputs. If customers have mixed circuits, then they would have to purchase separate controllers for each voltage source.

Q: How does cost compare for embedded metering versus utility-type metering for a building with multiple tenants, say 20 tenants?

A: Costs probably are similar or lower than traditional metering in hardware. The biggest advantage is the customer can collect the data for analysis purposes over specific protocol, historical trending, alarm alerts, and additional savings is the electrical room size reduction. It can be reduced by 50%.

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