Product Info

On-Demand 1.2 Overview 2
Technical Brief
Introduction
The Aclara RF™ network is an advanced metering infrastructure or AMI that
allows for meter readings to be transmitted directly to a utility along with various
system performance and diagnostic information. It allows for unmanned reading of
water and gas meters. It is currently deployed in more than 700 utilities worldwide.
The three major components of the Aclara RF™ Automated Metering
Infrastructure system are:
Meter Transmission Units (MTUs) - These are connected to the meter, whether
wired to it for water, or physically attached for gas. They take hourly readings
from the meter and transmit them via radio frequency on a regular basis. Each
meter in the system will have an MTU.
Data Collector Units (DCUs) - These are installed in the field to collect readings
from nearby MTUs. The DCU performs some treatment and consolidation of these
readings and transmits the, typically via cellular service, to the Network Control
Computer.
AclaraONE - This is the head end, the brain of the system and its command center.
It collects all the data from the DCUs in the system, stores it, and uses a web portal
to present that data in usable form for the utility.
MTUs
Aclara’s series 3000 devices connect to the meter, record readings hourly, and
store them in memory. They can hold 12 readings in memory, and every 6 hours
they transmit those readings via radio frequency to nearby DCUs.
Since the MTU can hold no more than 12 readings, each hour a new reading is
added to memory and the oldest reading, the one that is 13 hours old, drops off.
Because MTUs transmit 12 readings every 6 hours, there is redundancy in the
readings transmitted. The first 6 readings from the 6:00 a.m. transmission will be
the last 6 readings in the noon transmission. By the 6:00 p.m. transmission, those 6
readings will have been replaced by 6 newer readings.
This redundancy means that if a transmission fails to reach the DCU for whatever
reason, the readings still have a second chance in the next transmission. Duplicate
readings are filtered by the DCU, so only a single hourly reading is transmitted to
AclaraONE.
Water and gas MTUs differ slightly in the way they connect to the meter. Gas
MTUs are attached to the face of the gas meter, and consequently cannot be
repositioned. (Meter-specific gas meter installation instructions are also available
on Aclara Connect.) A water MTU is connected to the meter register by means of a
three-wire cable. Because water meters may be installed indoors in cold climates,
and either outdoors or in pits in warm climates, the length of the cable allows for
some flexibility in placement of the MTU for optimum radio signal propagation.