User's Manual

3UHOLPLQDU\
Contact Elster Electricity for information
30 November 2006 2-3
REX Meter
Technical Manual 2 Product Description
Meter Engine. Multiplication and other calculations are performed using the
meter engine. The meter engine contains the digital signal processor (DSP) with
built-in analog-to-digital (A/D) converters capable of sampling each current and
voltage input. The DSP multiplies the signals appropriately, using the factory-
programmed calibration constants.
Microcontroller. The microcontroller performs many different functions, for
example:
■ communicates with the meter engine and EEPROM
■ accumulates energy usage data and computes kWh, kW, TOU kW, and
load profiling data
■ sends output pulses
■ controls the LCD
■ controls the optical port
■ provides an option board interface
The microcontroller and the meter engine communicate with each other
constantly to process and accumulate energy measurements. When the
microcontroller detects a power failure, it initiates a shutdown. A shutdown is the
process that stores billing and status information in EEPROM.
EEPROM. The REX meter uses EEPROM for nonvolatile storage of
manufacturing data, meter configuration data, and energy measurement data.
During a power failure, the EEPROM provides storage of all the information
needed to ensure the integrity of the energy calculations, including the following:
■ configuration data
■ billing data
■ meter status
■ constants
■ energy usage
Billing Data
Metered Energy. The meter engine samples the voltage and current inputs,
computes energy, and sends these measurements to the microcontroller. In the
meter engine, each pulse is equal to one K
e
defined as secondary-rated Wh per
pulse. The K
e
is specific for each meter form factor, as defined in Table 2-1.
Table 2-1. K
e
for each REX meter form factor
The REX meter can measure any one of the following quantities:
■ kWh delivered
Form K
e
K
h
1S 0.1 1.0
2S 0.1 1.0
3S 0.01 1.0
4S 0.01 1.0
12S 0.1 1.0