SGM-DD Smart Grid Four-Line Meter 

Product information

The SGM DD 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 
• Additional multi-purpose bay for use with a variety of communications modules, 
• e.g. BAB or Wm-bus module 
• Illuminated display 
• Flexible measurement via shunts with intrinsic immunity to harmonics and external magnetic fields: +A or -A with reverse running lock, +A/-A bi-directional, 

• LMN-485 bus interface for remote communication with or without TLS security in accordance with BSI TR-03116-3 
• PIN-protected data display and output 
• Front optical interface with two operating modes (D0 according to IEC EN 62056-21 Mode C, DSS according to FNN) for local data provision and readout 
• No power readout function 
• Test point mode 
• Installation mode with phase sequence and undervoltage/overvoltage indication 
• Internal or external battery with battery management 
• Operation via buttons or via light pen 
• Integrated real-time clock 
• Multifunction display for metrological and historical data over 2 years, based on accurate daily meter values and other consumption data 
• Monthly value storage on the first of each month 
• Internal and external tariffing with key data regulation 
• Tariff period archive for external tariffing 
• Internal logbook 
• Dual-tariff version with external control via accessory terminals 
• Legally compliant display of consumption data with SMGW operation 
• Load cycle display 
• Sturdy, low-emission power supply

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. 

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

• Measurement in one direction with reverse running lock 
• Measurement in two directions: +A and -A 
• Measurement of power consumption over two lines with supply over one line 

The current sensors used are robustly mounted, precise shunts, suitable for accuracy class B. The actual power values in all the phases are registered internally and are available over the data interfaces. The measurement mode is set at the factory in accordance with metrological requirements. 

For start-up and connection tests, a convenient tool is available to the installer after removing the terminal cover, enabling display of phase sequence and checking/displaying overvoltage or undervoltage. 

To simplify readout after shutdown of the installation or removal of the meter, the complete data set can be read out up to five times per day using the external battery. 

The battery can be replaced without opening the calibration seal. 

Summer/winter time control can be set accurately in the event of changes to legal requirements. 

The active power values are recorded in a ring buffer as historical data over a period of two years and can be displayed for individual days with customer-modifiable password protection. The daily meter reading cycles and tariff switching times can also be viewed with the same PIN protection. A monthly stored values memory enables convenient checking of the billing period. The front optical interface is used for local provision of measurement data and device information in accordance with SML/COSEM at one-second intervals or via D0 according to IEC EN 62056-21 Mode C. These functions are also protected by a multilevel PIN. PIN entry is via the optical button or the mechanical button. 

The LMN bidirectional RS-485 interface (only in connection with the optional BAB adapter) supports system communication in bus operation. The baud rate is 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. 

The dual-tariff function with external control is available via terminals 13 and 15 of via an internal tariff schedule. 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. Additional 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. Other operational results are also recorded in the logbook. To use the switching functions with the power limitation or prepayment function, the externally connectible terminal switching module is required in addition to the smart metering system with secure gateway and  GCU-S control device.