Introduction and overview

The Power-Rail PLC is a single-phase 80Amp keypad based, split prepayment meter in a DIN rail-mount housing, using PLC communications between the meter and the customer interface unit. The meter uses the standard PLC customer interface unit which is common to the Single Phase SSP PLC and Three Phase PLC products.

The meter is typically installed in a pole-top enclosure or secure street kiosk and the small size of the product means a smaller street kiosk can be used. As with the SSP PLC and Three Phase PLC, the meter can be accessed remotely using the PLC Remote Access Terminal

Features

• Compact meter design, with DIN rail-mount layout
• Ideal for new reticulation in areas where low installation cost is a primary concern
• Proven Cashpower keypad technology
• Power Line Carrier communication between meter and the customer interface unit
• Quick and easy to install - uses existing household wiring, ideal when additional communication wire is not convenient.
• Significant Reverse Energy (SRE) detection
• Programmable software power limit
• STS Compliant
• Language independent user interface
• SABS 1524-1 compliance is pending

Split Metering Functionality

The split prepayment meter consists of two parts, the meter and the customer interface unit. Communication between the meter and the customer interface unit is by means of Power Line Communication (PLC), using existing household wiring; - no additional communication wires are required. The customer interface unit is a compact unit with a userfriendly keypad and display. It may be installed in any convenient location in the consumer’s home where there is an electrical socket outlet.

The prepayment meter contains all critical metering, number decryption and load control functionality. It operates independently and is immune to any form of tampering on the customer interface unit. The meter is usually installed in a secure, locked enclosure, typically a pole-top enclosure. 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.

Benefits

A key feature of the Cashpower Power-Rail PLC split prepayment meter is the ability to use standard household wiring for communication between the customer interface unit and the prepayment meter. This capability enhances retrofitting or replacement of conventional meters with prepayment meters.

The benefits include lower cost of installation, as no new cabling needs to be laid, and speed of installation. The keypad or customer interface unit is simply plugged into any existing mains outlet and, after a simple commissioning procedure, the unit communicates with the remote meter up to a distance of typically 200 m. The maximum communication distance is dependent
upon network attenuation and interference.

Customer interface

The customer interface is connected by a power cord to an existing mains outlet in the household. Under normal conditions, when there is sufficient credit in the meter, the customer interface unit operates directly from mains voltage. However in the event that the meter credit expires and the meter disconnects power to the house, the customer interface unit is fitted with two standard
AA Alkaline batteries to allow the customer to re-enter a new credit voucher.

The customer interface has a large backlit display with configurable functionality. The customer or field technician can access meter parameters by entering specific register information using the keypad. In addition, the customer interface unit has audible low credit warning tones that can be silenced with a key press.

Meter status and diagnostic indicator

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

Optical interface

As a standard feature, the Power-Rail PLC meter offers an IEC 62056-21 compliant optical communications port. This allows the utility to access a variety of information stored inside the meter using an optical pick-up.

Anti tamper features

The split configuration of Power-Rail PLC meter significantly reduces the risk of tampering, especially considering that the meter is installed in a remote, secure location. The meter is mechanically sealed against tampering through the use mechanical clips and inaccessible assembly screws. Utilitysealed 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.

The meter also has a feature allowing detection of Significant Reverse Energy. 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 Significant Reverse Energy be detected.

Disconnect on Power Fail

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

Remote Access

The meter is capable of “upstream” communication to a concentrator at a kiosk, low-voltage distribution transformer or mini sub-station. This feature enables the Power-Rail PLC meter to be remotely accessed by the utility to check the remaining kilowatt-hours, total kilowatt-hours used to date, maximum power limit and other useful parameters stored by the prepayment meter.

Communications capability can be implemented by using the Remote Access Terminal which can be fitted into a secure enclosure or substation to provide connectivity via wireless technology to a power utility’s back office. By means of the concentrator, bi-directional communication is possible. A message can be sent to each meter to request information and prepayment vouchers (purchased by a specific consumer or generated for maintenance purposes) could be sent in a virtual payment process.

Prepayment / Credit feature

Using supplier-specific 20-digit STS prepayment vouchers which are unique to each meter, the Cashpower Power-Rail PLC prepayment meter can be converted into a standard credit meter, while retaining some of the useful features of a prepayment meter.

These include the maximum power limit and remote customer interface unit for customer convenience. The meter can be switched between credit mode and prepayment mode when necessary, using a 20-digit STS prepayment voucher generated by the prepayment system.

Surge protection

The Power-Rail PLC meter is supplied with a surge arrestor that is capable of sustaining up to 30kA during transients.