Federal Energy Regulatory Commission Progress Report of Advanced Metering in 2006

FERC (Federal Energy Regulatory Commission)



Docket number 06-2-000



AMI data collection involves the collection and retrieval of meter data without physically visiting the

meter site, and is typically done by means of a fixed network.59 Today, electric utilities use various

types of AMI systems. The different types of AMI systems available on the market today are:

  • Broadband over power line
  • Power line communications
  • Fixed radio frequency (RF) networks
  • Systems utilizing public networks (landline, cellular, or paging)

Each of these different AMI system types are examined in more detail below.

Broadband Over Power Line (BPL)60

BPL works by modulating high-frequency radio waves with the digital signals from the Internet.

These high frequency radio waves are fed into the utility grid at specific points, often at substations.

They travel along medium voltage circuits and pass through or around the utility transformers to

subscribers’ homes and businesses. Sometimes the last leg of the journey, from the transformer to the

home, is handled by other communication technologies, such as Wi-Fi.

As seen in Figure III-2 below, substations receive power from power plants over high voltage lines,

and then step down the voltage to transmit power to distribution transformers over medium voltage

circuits. Each medium voltage circuit services 20-25 distribution transformers which convert the

medium voltage down to the voltage level used within most homes and businesses (110v/220v).

Between one and six homes are connected to each distribution transformer which translates to about

100 homes passed per medium voltage circuit.

(59 A fixed network refers to either a private or public communication infrastructure which allows the utility to

communicate with meters without visiting or driving by the meter location.

60 The information in this section relies heavily on facts provided in a seminar presented in 2005 by UtiliPoint:)

Ethan Cohen, UtiliPoint, “BPL Hope, Hyperbole, and Reality,” April 2005

Power Line Communications (PLC)

PLC systems send data through powerlines by injecting information into either the current, voltage or

a new signal. This can be accomplished by slightly perturbing the voltage or current signal as it

crosses the zero point or adding a new signal onto the power line. The system normally has equipment

installed in utility substations to collect the meter readings provided by the endpoint, and then the

information is transmitted using utility communications or public networks to the utility host center for

the PLC system. The low frequency signals used in PLC communications in the United States are not

filtered out by distribution transformers.

PLC systems are particularly well suited to rural environments, but have also been successfully used in

urban environments.62 For utilities with both rural and suburban areas in their service territory, PLC

provides an option for using one AMI technology for the entire service territory for electric meters.

PLC systems initially targeted residential and small commercial metering, but are now able to read for

larger customers as well.

61 “Is the Ambient system compatible with all distribution systems?” Frequently asked questions on Ambient

Corporation website, http://www.ambientcorp.com/pages/faqs-UTILITY.htm, “For all practical purposes, yes. In the US and

Canada, all systems are essentially the same from a BPL perspective. In other countries, differences in voltage, frequency and

configuration (specifically, the number of customers on each distribution transformer) can impact equipment and system

design. In general, the higher density of customers per transformer in Europe and other countries works in favor of BPL.”

62 PPL Electric Utilities has used PLC in Pennsylvania and, more recently, Pacific Gas & Electric selected a PLC

system for its electric AMI system for both rural and suburban areas

Fixed RF Systems

In basic fixed radio frequency (RF) systems, meters communicate over a private network using RF

signals. Each meter communicates via the network directly to a data collector or a repeater. Repeaters

may forward information from numerous endpoints to the more sophisticated devices called data


Data collectors often store the meter readings from meters within range. The data collectors then

upload the meter readings to the AMI host system at preset times using the best communication

method available, ranging from public networks to microwave to Ethernet connections. The

communications between the data collector and the network controller are usually two-way, and allow

the network controller to query for a recent meter reading and the status of one or a group of meters.

From 1994 to 1999, this type of automated meter reading system was selected for every large fixed

network deployment in the United States. 63 Since 1999, fixed RF has been selected in seven of the 12

large fixed network deployments.

More advanced RF networks have also been developed and implemented. Within these more

advanced systems, the meters themselves may form part of the network, and meters are not required to

communicate directly or indirectly with a repeater or the data collector. One example of an advanced

RF AMI network is shown below in Figure III-3. In this system, endpoints can communicate directly

with towers (similar to super data collectors) or via a ‘buddy” meter. Other advanced systems are

designed with endpoints that form a mesh network, and where some of the endpoints within the mesh

may function as data collectors and meters. The flexibility provided by advanced RF AMI systems is

generally thought to offer advantages in terms of better coverage and more robust communications.

One of the key features of the more advanced RF networks that appeal to utilities is the ability of the

network to “self heal.”64 If the endpoints have more than one communication path to the main hub of

the system, and the best path is no longer available, endpoints can change their communication path.

This is very important to utilities because changes in the service territory are ongoing. New buildings

are constructed, trees or other shrubbery are planted or grow, and other changes occur which affect RF


Major vendors of fixed RF systems include Cellnet, Elster, Hexagram, Itron, Sensus/AMDS, Silver

Spring Networks, Tantalus, and Trilliant.

63 See

Systems Utilizing Public Networks

These systems utilize existing public networks such as paging, satellite, internet and/or telephony

(cellular or landline) networks to provide for communications between meters and utilities. One key

advantage of these systems is the ability to deploy AMI across a wide area with low densities, and the

possible lower upfront cost of deployment since the utility does not need to build a private

infrastructure. Some systems rely on paging networks while others rely on cellular or landline

telephone networks. Some have used satellite communications. Three key limitations include: being

subject to the coverage provided by the public networks; changing protocols (this is especially true in

the cellular segment); and operational costs.

With AMI systems based on public networks, if there is coverage at the customer location, installation

costs are limited to installing the new endpoint, and setting up the service. Utilities are not required to

install any communication infrastructure, which can speed up the deployment process.

All of these systems have been used for larger customers and small rollouts of AMI, but recently these

systems are being considered for much larger rollouts for smaller customers.65

65 Hydro One in Ontario announced in April 2005 it had selected Rogers Wireless Inc./SmartSynch to provide

25,000 “Smart Meters” as part of a pilot program. The Smart Synch system relies on a selection of various public networks

for communications.

Meter Data Management

Meter data management provides utilities a place to store meter data collected from the field. Utilities

that install AMI usually invest in meter data management to provide storage for the large number of

meter readings that will be collected each year per meter. If utilities opt for hourly interval data, this

results in 8,760 meter readings per meter year, compared to 12 each year for a meter that is read once

per month. For a utility of even modest size, the storage requirements and data processing can become


Meter data management can also be configured to meet the specific requirements of other utility

applications. For example, with meter data management, meter data can be provided in the same

manner to all applications, or it can provide data in the exact form that each application requires. If

the utility bills residential customers on the total usage for the billing period, the meter data

management can total all of the daily reads to provide the billing system the total usage for each


READ FULL ARTICLE AT: http://www.ferc.gov/legal/staff-reports/demand-response.pdf

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