User`s guide

1-1
1 PRODUCT DESCRIPTION
1.1 Product Overview
A traditional electric power meter incorporates an electric motor whose speed of rotation
is directly related to the amount of power being used by the customer. The motor drives
a collection of gears and dials that provide a visual indication of the power consumed
since the meter was installed. A person from the utility company must visit each meter
on a regular basis to record these readings so that the utility can provide an accurate bill
to the customer. The cost of this activity is quite high and continues to increase as
salaries, vehicle costs and insurance rise.
Some meters can also provide an electrical signal (a pulse) for each watt or kW that has
been consumed. These pulses can be counted and recorded by another device
mounted near the meter. These devices usually contain modems connected to wired
phone lines and will occasionally call a central computer to report their readings.
Therefore on-site visits are eliminated, the chances for errors are reduced and the
information is timelier.
Technological advances now permit microprocessors, memories and precision
measurement circuits to be incorporated within the electric meters themselves. The
mechanical dials have been replaced with digital readouts, and a modem or other
communications device may be included to allow for remote data collection. Much more
information is available than with traditional meters such as power factor, phase angles,
histories of usage, etc.
With this rapid evolution came a need to develop a universal way to communicate with
any of these meters, regardless of the manufacturer. A standard was developed by the
Accredited Standards Committee on Electricity Metering, C12, and was approved by the
American National Standards Institute, or ANSI. Any meter following this standard is
expected to behave and communicate in a consistent manner.
Yet there remain problems associated with wired telephone service. There may be no
lines available in the area where the meter is to be installed. In some cases it may be
physically impractical or too expensive to run a phone line. The communications speeds
offered by the internal modems are relatively slow, resulting in long communications
sessions. Finally the monthly charges for phone service may outweigh the advantages
of an automated system.
Metretek’s DCM-200 is a wireless system designed to connect to an ANSI C12-
complient meter and transfer its information over common digital cellular phone
networks. The unit supports 850 / 900 / 1800 / 1900 MHz GSM, the primary cellular
system used throughout most of the world. Depending upon the cellular service
provider’s capabilities, the DCM-200 can originate calls, receive calls or both. The DCM-
200 can communicate with another modem using a circuit-switched data (CSD)
connection, or can use the general packet radio standard (GPRS) to exchange
information over the Internet.
Primary power for the DCM-200 is obtained from the AC line itself, with a small backup
battery used for emergency call-ins during power outages. An industrial grade fiberglass