gREX AMI meter

Built on the patented REX meter platform, Elster’s gREX meter offers the same state-of-the-art AMI capabilities that provide significant value in residential applications.

The gREX meter offers a flexible platform providing metering functions including bidirectional energy, power measurement, time-of-use metering, interval data recording, and critical peak pricing. With the EnergyAxis System, any of these features can be controlled remotely.

gREX meters include an integral Elster-designed frequency hopping spread spectrum transceiver operating in the 900 MHz band. This 900 MHz module provides excellent communications range and penetration, allowing the gREX meter to act as an intelligent two-way element in the Elster EnergyAxis System.

The gREX meter has a small footprint that allows for installation in the smallest physical locations. It conforms to typical IEC standards as well as ANSI electrical standards.

gREX meters are available in most common residential wiring configurations.

Quantities Demand and TOU Interval data recording Service control switch Security  
Standards compliance Style numbers About EnergyAxis  

First energy source

  • kWh delivered
  • kWh received
  • kWh sum (delivered + received)
  • kWh net (delivered – received)


Second energy source

  • kWh delivered
  • kWh received
  • kWh sum (delivered + received)
  • kWh net (delivered – received)

The demand source is used for up to 3 demand registers:

  • kW delivered
  • kW received
  • kW sum (delivered + received)


The 3 demand registers can be total kW or kW for a specific tariff. The gREX meter supports a 4-tariff, 4-season TOU rate.

Demand is computed on 15, 30, or 60 minute intervals.

The gREX meter provides interval data recording in 1 or 2 channels. The selectable interval lengths are 15, 30, or 60 minutes. End of interval (EOI) energy snapshots are provided to improve data validation.


The gREX meter interval data is periodically transferred to the local data collector where it is stored until transferred to the EnergyAxis Metering Automation Server (MAS) via a public wide area network (WAN) connection.

The gREX meter’s optional 100 A integrated service control switch can disconnect and reconnect the electrical service. Based on significant field experience, the gREX meter’s service control switch has been optimized to provide low contact resistance for increased life. The gREX meter supports advanced demand limiting and lockout functionality. The switch can be operated remotely through the EnergyAxis network or locally at the meter.

The gREX meter uses full 128-bit AES encryption when communicating over the EnergyAxis network. The meter’s many status and error alerts are reportable though the network, quickly notifying the utility of possible meter tampering or energy theft.

The gREX meter meets or exceeds the following standards for electricity metering:


  • IEC 62052-11 (2003): General requirements, tests and conditions (Metering Equipment)
  • IEC 62052-21 (2004): General requirements, tests and conditions (Tariff and load control equipment)
  • IEC 62053-21 (2003): Particular requirements-static meter for active energy (Classes 1.0 and 2.0)
  • ANSI C12.19 (1997): Utility Industry End Device Data Tables
  • ANSI C12.22 (2008): Protocol Specification for Interfacing to Data Communication Networks (draft)
  • AS/NZS 4268 (2003): Radio Equipment and Systems – Short Range Devices – Limits and Methods of Measurement
  • NMI M 6 (2004): Pattern Approval and Initial Verification of Electricity Meters and Associated Transformers: Definitions, Metrological and Technical Requirements

The meter's nameplate provides important information about the meter, such as LED pulse setting, EnergyAxis network information, and manufacturing information. The nameplate also displays the Elster style number.

For more information, download the gREX meter nameplate and style number data sheet.

EnergyAxis System

EnergyAxis is the most advanced and complete suite of smart grid solutions. Developed by Elster, the world's leader in smart metering, the EnergyAxis System architecture is the most interoperable smart grid communications solution available. With verified applications for demand response, distribution automation, outage detection/restoration, revenue protection, we know how to seamless integrate with almost any operation.


EnergyAxis is engineered on open standards, allowing us to interface with the greatest range of powerful third-party technologies and providing you with the widest choice of communication paths possible. Our unsurpassed interoperability enables us to partner with over 40 smart grid companies and apply all relevant technologies to meet your need, and they are proven to work.


Elster is committed to supporting utility initiatives in energy conservation. Through its open architecture, EnergyAxis is able to integrate with third party electric load control devices, demand-side management devices, in-home displays, and pre-payment services.


Visit the EnergyAxis Web site for more information on Elster's advanced metering infrastructure solutions.