In early 2005, AMPS began replacing manually read electric power
meters with automated devices called Turtles. Automated Meter
Reading, or AMR, has a number of benefits. For one, once fully
deployed, AMR allows AMPS to eliminate the cost of sending an
employee out to locate and read every meter in the system. As a side
benefit, eliminating hand written read sheets and manual data entry
into the billing system each month reduces the number of possible
human errors in the billing process.
Several different AMR technologies are in
currently being used in the electric utility industry. Some systems
utilize a radio receiver to collect meter data, this system requires
a "meter reader" or utility employee to visit each meter location
and request meter information via a hand held transmitter. The
information collected by the transmitter is then downloaded into the
utilities billing system for customer invoice generation. Others use
stationary radio receivers mounted on poles in
neighborhoods to collect local meter readings, once the information
is collected it is then transmitted to the utilities billing office
for customer invoicing. The system AMPS has
chosen is called the Turtle system from Hunt Technologies, and which
transmits meter readings over the actual power lines without the
need for expensive radios.
Electric power meters are very simple devices conceptually. They are essentially electric motors which turn at a speed proportional to the amount of power passing through them. The motor speed is governed by the physical construction of the meter and cannot be changed except for minor adjustments which can be made to correct a meter that is aging and running too slow - they cannot be made to run too fast. This motor is then connected to a series of gears which move the dials on the face of the meter in an exact ratio such that the number of turns of the motor is converted to a number of kilowatt-hours of energy usage. This counting and conversion calculation is a fixed ratio and never varies, much as the gears in a watch always allot 60 seconds to each sweep of the minute hand, and 60 minutes to each hour. This makes modern electric meters extremely reliable and rugged, essential in our climate. To implement AMR with Turtles, a small electronic module is installed inside a standard power meter - no other change is made. This module simply counts the number of turns of the motor inside the meter and reports the number at regular intervals using a signal transmitted over the power line. This information is collected by a receiver installed at a substation and held until requested by a computer at the main office.
Several times a week AMPS calls the receivers to keep current information on hand and to monitor for possible electric system problems, a Turtle suddenly not reporting can indicate a problem that should be checked immediately. At the end of each billing period the receivers are read from the office, and the most current readings are transferred electronically to the billing system. The Turtle software calculates the number of kilowatt hours used by each location from the counts reported by the Turtle modules, and sends the actual energy usage to the billing software, essentially duplicating the calculation that is performed in the meter by the gears and indicators. This provides an excellent checkpoint to monitor the health of the Turtles; if a spot check of a meter shows a mechanical reading identical to the most recent Turtle data, the system is working correctly. If there is a significant difference, we investigate the problem and correct it.
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