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
- 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)
- 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.
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.
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
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.
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
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.
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
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
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.
The Power-Rail PLC meter is supplied with
a surge arrestor that is capable of sustaining up to 30kA
for more info - SSP Power Rail Specifications - "allow
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