Introduction and overview

The Split Single Phase (SSP) meter is a compact, two wire, keypad-based prepayment electricity meter which comprises two parts, the Energy Management Unit (EMU) and the Customer Interface Unit (CIU).

User interaction with the meter and access to meter information (such as a low credit warning, energy consumption, and load contactor status) are available using the keypad and LCD display on the CIU

Split Meter Concept

The meter consists of two parts namely, the CIU and the EMU. The CIU is the customer’s only interface with the meter, and is a compact unit with a user-friendly keypad and display. It is usually installed in a convenient location in the consumer’s home - remote from the EMU, and is connected to the EMU with a pair of communications wires.

The EMU contains all critical metering, number decryption and load control functionality. It operates independently and is immune to any form of tampering on the CIU interface. The EMU is usually installed in a secure, locked enclosure, typically a pavement kiosk or pole-mounted equivalent. It is outside the consumer’s home to facilitate easy inspection by the utility at any time and to reduce the opportunity of fraud by tampering. As an option, the EMU can be supplied with its own LCD display and keypad, which allows the utility to view important meter parameters without the need for an interrogation tool.


      • Compact meter (EMU) design, with British Standard layout
      • Easy to install and ideal for new reticulation as well as retrofitting of credit meters with BS footprints
      • Proven keypad technology
      • Meter provides valuable information to help consumers effectively manage and budget their electricity consumption
      • Galvanically isolated communication to CIU for consumer safety
      • Tamper detection
      • Significant Reverse Energy (SRE) detection
      • Programmable software power limit
      • Advanced commissioning / decommissioning feature
      • STS Compliant
      • Language independent user interface
      • Optional large LCD and keypad at the EMU
      • Improved sealing against ingress of insects
      • Easy to see diagnostic LED’s on the EMU for Meter state indication and communications
      • High surge withstand capability for areas prone to lightning or other line surges
      • SABS 1524 and IEC 62052-11, IEC 62053-21 compliant

Principle of operation

The SSP is most suitable for new reticulation. The communication wires are non-polarised, which simplifies
the installation. In addition, the communication lines are galvanically isolated from the mains, thereby ensuring
personal safety.

The communication wires can be included as separate cores in a concentric reticulation cable and provide a
very robust communications interface between the EMU and CIU over a distance of at least 130 metres.

User-friendly customer interface

The EMU is operated via the CIU in exactly the same way as other meters in the Meter Mate range. User interaction with the meter and access to meter information (such as a low credit warning, energy consumption, and load contactor status) is available using the CIU’s keypad and large LCD display. The makes use of clear, language-independent icons.

In addition, various audible tones are sounded under different conditions (e.g. Low Credit Alarm).

Meter status and diagnostic indicators

The EMU includes an LED status indicator. This allows a technician to view the state of the meter without the need for specialised interrogation tools or having to gain access to the consumer’s premises. Information such as tamper status, power limiting, commissioned status and credit status are available.

The EMU also features a dedicated diagnostic LED for the CIU interface. It can indicate the presence of “Open” or “Short” circuited communication lines. This is a valuable visual aid that assists the technician to validate the installation and determine probable fault types.

Local HMI

As an option, the EMU can be supplied with a local Human-Machine Interface (HMI). This includes a large pictographic/numeric LCD, a keypad and an audible buzzer. This allows the utility to inspect and update various meter parameters manually.

Interrogation port

As a customer option, more detailed information and programming is achieved via the standard interrogation port at the rear of the EMU.

Optical interface

As a standard feature, the compact Gemini family offers an IEC 62056-21 compliant optical communications port. This allows the utility to access a variety of information stored inside the meter and to upload it to a hand-held unit.

Tamper detection

The split configuration of Gemini CSM meters significantly reduces the risk of tampering. The EMU is installed in a remote, secure location and is mechanically sealed against tampering through the use of a factory-sealed screw plug on the rear panel, and a utility-sealed wire seal on the front of the meter. The use of these mechanical seals ensures that there are visible signs of tampering if unauthorised entry to the system is attempted.

In addition, the units are equipped with a tamper sensor that will automatically disconnect the power to the load in the event of tampering.

The meter also has a feature allowing detection of Significant Reverse Energy (SRE). If the line and load wires are swapped during installation, the meter will continue to operate and decrement credit but can be factory programmed to tamper and disconnect the load should SRE be detected.

Surge protection

The meter has been designed to have a surge voltage withstand that significantly exceeds the requirements of both SABS 1524 and IEC 62052-11.

Depending on the environment, the customer may want to protect the installation by providing additional surge current protection. The compact Gemini family has the option of being supplied with a built in surge arrestor that is capable of sustaining up to 30kA during transients

Communication line protection

The communications interface can withstand voltage surges of 6kV, however it is recommended that one of the communication lines be earthed at the EMU for additional protection. Should the customer not want to earth a communication line during installation, the meter can be fitted with protection circuitry in the terminal cover.

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