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Smart grid four-line meter FNN basic meter for iMSys 

The  SGM-D4 system-ready four-line meter is a standard device for measuring active power with residential and commercial customers as a modern metering device.  

The basic meter, smart meter gateway and control box together form the device basis for automation in modern distribution grids (smart grids). 

In the extended version as a smart metering system (iMSys), a TLS-secured communication channel is established via the LMN-485 bus to the secure smart meter gateway. The meter acts as a metering device with secure data transmission. The meter has an FNN-compliant integrated LMN-485 bus interface for system connection and an optical data interface (DSS).

The SGM-D4 can be connected directly as a unidirectional, bidirectional or supply meter.  

Product information

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Product information

The SGM D4 is a sturdy device with the following features: 

  • Housing according to FNN specification for three-point mounting with top-hat rail for integration of additional devices 
  • Flexible measurement via shunts with intrinsic immunity to harmonics and external magnetic fields: +A (consumption meter) or -A (supply meter), +A/-A (bidirectional meter) or totalizing supply meter 
  • LMN-485 bus interface for remote communication with TLS security according to BSI-TR-03116-3 
  • PIN protection for extended data display and data output 
  • Front optical interface for local data provision (INFO interface) 
  • LCD according to FNN specification for display of metrological and historical data over two years,  two lines with special symbols  
  • Output of grid status data 
  • Single-tariff or dual-tariff version with external control via accessory terminals as an option 

Standard functions

In accordance with statutory provisions, the meter acts as a reliable and secure metering device for acquisition of billing-related active power quantities and grid-friendly measurement data and parameters, such as effective values of line voltage and current, power, phase angle and line frequency. 

Active power is measured in both directions, with the following measurement modes being available: 

  • Unidirectional meter (+A or -A)
  • Bidirectional meter (+A and -A)
  • Supply meter, totalizing without reverse running lock (-A) 

The current sensors used are sturdily mounted, precise shunts, which also optionally enable Class b accuracy. The actual power values in all the phases are registered internally and are available over the data interfaces. Actual power values on all lines are logged internally and available over the data interfaces. The measurement mode is set at the factory in accordance with metrological requirements. 

The meter also provides the following grid status data (grid functions): 

  • Active power (total active power P as well as individual phase values PL1, PL2, PL3) calculated as average values over 1 second, resolution 0.1 W 
  • Effective values of line voltages UL1, UL2, UL3 calculated as average values over 1 second, accuracy 1% of measured value, resolution 0.1 V 
  • Effective values of line currents IL1, IL2, IL3 calculated as average values over 1 second, resolution 0.1 A, accuracy 1% of measurement 
  • Phase angles φL1, φL2, φL3, accuracy/resolution 1° relative to the fundamental frequency 
  • Phase angle between external line voltages U2/U1 and U3/U1 
  • Line frequency fline, accuracy 1%, resolution 0.1 Hz 

The daily, weekly, monthly and annual values of active power over a period of two years are recorded in the ring buffer as historical data and displayed under PIN protection. The front optical interface is used for local provision of measurement data and device information according to SML/COSEM at 1-second intervals. This function is also PIN protected. The PIN entry is made via the optical button. 

The LMN bidirectional RS-485 interface serves for system communication with an SMGW at a baud rate of 921.6 kbit/s.  The protocols used are HDLC in the connection layer and SML/COSEM in the application layer. In the “smart metering system” variant communication is TLS-secured in accordance with BSI TR 03116-3.

Optional Functions

As an option, the dual-tariff function with external control is available via terminals 13 and 15. The tariff registers in both power directions, as well as the current tariff, are shown on the display. This function and the display of historical data are disabled by the gateway in the smart metering system variant. Other functions such as tariffing, measurement data recording and control operations are basically assigned to the secure gateway or the respective control device. 

Removing the terminal cover or attempted influence using magnets is detected as manipulation and recorded as such.  

Modern metering device

Smart grid four-line meter FNN standard

In the design versions for 60 A or 100 A, MID Class A/B, the meter can be used as a stand-alone device (modern metering device) in all customer installations directly connected via four lines. Typical application areas include residential customers, multi-unit dwellings, customers with self-generation and feed-in into the public power grid, small businesses and site facilities.

Smart metering system

Smart grid four-line meter FNN basic meter for iMSys

In combination with the smart meter gateway, the SGM-D4 forms a smart metering system (iMSys) as legally prescribed for customer installations with annual consumption greater than 6,000 kWh and installations with feed-in into the public power grid as described by the German Renewable Energy Resources Act (EEG). For use in load management and with renewable energy feed-in, a control box can be used as an additional component connected through the gateway to the control center via the CLS interface.

Your contact

Beppo Knorr

Head of Sales


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