Introduction and overview

The Split Single Phase (SSP) Power Rail meter is a compact, two wire, keypad-based prepayment electricity din rail mounted 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

Cashpower Power-Rail consists of two parts namely, the Customer Interface Unit (CIU) and the Energy Management Unit (EMU).

The CIU is the consumer’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 inside the consumer’s home - remote from the EMU -
and is connected to the EMU with a pair of communications wires. The connection of these wires at the EMU is achieved by means of a plug in connector, facilitating easier installation and maintenance. The EMU contains all critical metering, number decryption and load control functionality. It operates independently of the CIU 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 reduce the opportunity to defraud or tamper with it.

Features

• Compact meter (EMU) design, with DIN rail-mount layout
• Easy to install and ideal for new reticulation in areas where low installation cost is a primary concern
• Proven Cashpower keypad technology
• Meter CIU provides valuable information to help consumers effectively manage and budget their electricity consumption
• Galvanically isolated communication to CIU for consumer safety
• Plug in communications connector on the EMU for easier utility access & maintenance
• Significant Reverse Energy (SRE) detection
• Programmable software power limit
• Advanced commissioning/decommissioning feature
• STS Compliant
• Language independent user interface
• Meter state indication LED and COMMS diagnostic LED at EMU
• High surge withstand capability for areas prone to lightning or other line surges
• High temperature withstand capacity
• SABS 1524 and IEC 62052-11, IEC 62053-21 compliant

Principle of operation

Power-Rail 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 consumer 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

Power-Rail is controlled via the CIU in exactly the same way as other meters in the Cashpower 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 CIU 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.

Interrogation port

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

Optical interface

As a standard feature, the meter 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 the Power-Rail meter significantly reduces the risk of tampering. The EMU is installed in a remote, secure location and is mechanically sealed against tampering through the use mechanical clips and inaccessible assembly screws. Utility-sealed wire seals can be field fitted to secure terminal screw inserts in place. The use of these mechanical seals ensures that there are visible signs of tampering if unauthorised entry to the system is attempted.

Power-Rail 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 in addition, the meter can be factory programmed to tamper and disconnect the load should SRE be detected.

Disconnect on Power Fail

Power-Rail has a unique feature to cater for the condition where the neutral link to the meter is removed. The meter can be personalised to disconnect the load if a power failure is detected, as would be the case when neutral is removed.

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 fitting an additional surge arrestor. Power-Rail has the option of being supplied with a surge arrestor that is capable of sustaining up to 30kA during transients.