Energy Meter

Smart power devices

The EFR family of devices for smart grids

EFR offers smart metering and smart grid solutions for comprehensive measurement and grid management tasks and is an accredited SMGW manufacturer (BSI-DSZ-CC-1000). Our smart power devices family consists of:

  • FNN basic meter (in various versions): SGM-D 1/2 with SMGW, SGH-S and GCU-S control unit;
  • mMe with single-phase meter: SGM-C2
  • mMe with three-phase or single-phase meter: SGM-C4
  • BAB adapter: MT 930 A

The SGM series gives you system-ready meters for measuring active power with residential and commercial customers. Also available as compact modern measuring devices (types SGM-C4 or SGM-C2) or an FNN basic meter (type SGM-D1/2). These devices are fully compliant with the statutory provisions of the Metering Point Operation Act (MsbG) and the Bundesnetzagentur (BNetzA) and can be securely linked to an SMGW.

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SGM-D (FNN basic meter)

Four-line smart grid meter

Four-line / direct, semi-indirect or indirect connection / +A/-A, four-quadrant measurement / RS-485 bus / TLS security

  • Housing conforms to FNN specification for three-point mounting with top-hat rail for integration of accessory devices
  • Flexible measurement via shunts with intrinsic immunity to harmonics and external magnetic fields: +A or -A with reverse lock, bidirectional +A/-A, direction-independent |A|, and four-quadrant measurement (pending)
  • RS-485 bus interface for remote communication with TLS security compliant with BSI TR 03116-3
  • Front-mounted optical interface for local data acquisition
  • Multifunction display for meter data and historical data
  • Sturdy, low-emission power supply
  • Measurement data and network quality parameters
  • Optional dual-tariff version with external control via accessory terminals
  • Optional built-in 120 A contactor for power limitation (pending)
  • Optional provision of time series (pending)

With its standard design for 5(100) A Class A/B MID-compliant service, this meter can be used as a stand-alone device for all customer installations directly connected over four lines. Typical application areas include residential customers, multi-unit dwellings, customers with self-generation and infeed into the public power grid, small commercial operations and agricultural operations. The version for semi-indirect or indirect connection with four-quadrant measurement is used for industrial and commercial customers.

In combination with the secure gateway, the SGM-D forms a measuring system for customer installations with an annual consumption greater than 6,000 kWh and installations with infeed into the public power grid in accordance with the statutory provisions of the German Renewable Energy Resources Act (EEG). In future, customers with load management and EEG infeed will receive the control unit as an accessory component that connects to the control centre through the CLS interface and the gateway. The secure gateway and the control or CLS device are integrated into this standard meter. Together they form the basis for the automation of modern distribution networks (smart grids).

Continuous advancements in distributed power generation and the growing popularity of electric vehicles create new applications for this family of devices, such as smart control of distributed storage components and regulated charging of vehicles according to dynamic grid status. The smart grid meter provides the required measurement data for these network service tasks, including real and apparent power, line voltages and currents, and line frequency.

Standard functions

In accordance with statutory provisions, the meter acts as a reliable and secure measuring device for the acquisition of billing-related parameters (active and reactive power) as well as measurement data and parameters related to network services used for network management. These include effective values of line voltages and currents, line frequency, active and reactive power, line outages including number and duration, and voltage surges and dips.

In the directly connected version the active power is measured in both directions, with the following measurement modes available:

  • Unidirectional measurement with reverse lock
  • Measurement of absolute magnitudes |A|: direction-independent sum of magnitudes on all lines
  • Bidirectional measurement +A and -A
  • Measurement of power consumption over two lines with supply over one line

The current sensors used are sturdily mounted, accurate shunts suitable for accuracy class B. Actual power values on all lines are logged internally and available over the data interfaces. The measurement mode can be set in the factory according to metering requirements. Four-quadrant measurement with +A, -A, +R and -R is available in versions with semi-indirect or indirect connection. The current sensors used for this are shielded converters.

Other functions such as tariff setting, measurement data recording and control tasks are basically assigned to the secure gateway or the corresponding control unit. However, the device is also optionally available with the dual-tariff function with external control to enable broad deployment amongst customers with low consumption.

The bidirectional RS-485 interface supports TLS-protected system communication compliant with BSI TR 03116-3. It is designed for bus operation with the HDLC protocol. The baud rate is 921.6 kbit/s, and the application protocol is SML/COSEM. The measurement data is constantly transmitted to the opposite party in push mode.

The meter enables display of historical consumption and generation data with PIN protection using an optical port and has an operating log implemented as a ring buffer. Removing the terminal cover is detected as tampering and recorded in the log.

The front-side optical interface supports local operation, and in push mode it provides online access to measurement data and device parameters at one-second intervals in compliance with SML/COSEM.

SGM-C4

Compact system-ready four-line meter
Modern measuring device

The system-ready SGM-C4 four-line meter is a standard device for measuring active power with residential and commercial customers as a “modern measuring device.” The meter has an integrated RS-485 interface for system integration. Designed as a compact unit, it fulfils the functional requirements of the FNN industry standard. The SGM-C4 can be connected directly for both power directions (consumption and infeed) and is also available as a dual-tariff meter with external control. With the BAB adapter connected externally to the RS-485 interface, the SCM-C4 can be upgraded to a “smart measuring system.”

SGM-C2

Compact system-ready four-line meter
Modern measuring device

The system-ready SGM-C2 four-line meter is a standard device for measuring active power with residential and commercial customers as a “modern measuring device.” The meter has an integrated RS-485 interface for system integration. Designed as a compact unit, it fulfils the functional requirements of the FNN industry standard. The SGM-C2 can be connected directly for both power directions (consumption and infeed) and is also available as a dual-tariff meter with external control. With the BAB adapter connected externally to the RS-485 interface, the SCM-C2 can be upgraded to a “smart measuring system.”

EFR MT930 communication adapter

For the EFR SGM-C device family

The BAB adapter enables secure connection of modern measuring devices in the EFR SGM-C series to a smart meter gateway in accordance with the provisions of the Measuring Point Operation Act (MSBG) and the BSI. The BAB adapter supports secure linking of a modern measuring device to a smart meter gateway (SMGW) in compliance with TR-03109. The communication interface of the modern measuring device sends data to the BAB adapter using the SML protocol in accordance with DIN 62056.21, and the BAB adapter is linked to the LMN interface of the SMGW. In addition to these properties, the requirements of technical guideline TR-03109 and in particular the provisions of the FNN requirements specification apply to interfaces and adapters.