FlexNet is the industry’s only solution for utilities that demand unmatched customerservice and pinpoint-accurate reads.Only FlexNet delivers Primary-Use licensing by the Federal CommunicationsCommission, which guarantees an uncluttered, crystal clear path for transmissions. That paves the way for an industry-leading two watts of power, making yourFlexNet system the only mass-deployed utility system to enjoy the highest levelof protection, power and productivity in North America.FlexNet Advanced Metering Infrastructure (AMI) solution is offered exclusivelyfrom Sensus Metering Systems. It provides real time information from the distribution system at a level unavailable previously as well as empowering electricity, gas, water andcombination utilities with a proven means to increase meter reading efficiency,reduce overhead costs and enhance customer service – simply, reliablyand with unlimited flexibility.
Simple Communications
FlexNet’s single-tier design relays communications directly from meter-to-receiver. The streamlined infrastructure eliminates complex databases, algorithms and store-and-forward nodes, while maintaining coverage over a large geographical area. The tower-based system allows for a turn-key deployment program, delivered via master agreements with nationwide owners of existing radio towers—eliminating easement and access issues. Optional, all-inclusive pricing ensures utility budget control.
Secure Reliable Transmissions
The FCC license awarded only to the FlexNet system clears the airways for your transmissions on this dedicated frequency. While others fight over shared bands, your reads will be sent and received seamlessly under this Primary-Use licensed spectrum. Your data collection is securely protected; FCC laws assure that any interference is removed immediately. This dedicated frequency allows Sensus to offer our clients the highest RF power in the industry. Two watts is at your fingertips, increasing range and reliability on endpoint-to-tower communications.Reliability is further ensured through an overlap of receiver endpoint coverage, data/message redundancy, and backup provisions.
Flexible Operations
FlexNet is designed to allow both one-way and two-way meter endpoints to co-exist in the same network, giving customers the freedom to apply FlexNet to all of their endpoints. Whether your needs are based in electricity, gas or water, or in an urban, suburban or rural landscape, FlexNet is the solution that gives protected results with the flexibility to adapt the system to your utility’s needs. The FlexNet system also offers options beyond the meter, including distribution automation, load control and demand side management.
1.1FlexNet’s Architecture
FlexNet’s data collection and command network consists of a Local RF network and a Regional Network Interface (RNI). The Local RF network consists of FlexNet transmitters and/or transceivers at the meter and Tower Gateway Base Stations (TGBs). TGBs, which use existing radio towers, have antennas installed at heights ranging from 200 to 650 feet. TGBs provide the best solution to cover large areas. In addition, they have the ability to store 30 days of data and provide eight hours of battery backup, should the primary source of power be interrupted. The RNI is the network backbone of the system. It receives and stores the reading data from the TGB(s). The RNI also monitors the system health of the TGB(s), while also keeping a 60-day log of metering data. The RNI provides network capacity for all of the TGBs in one local RF network.
How FlexNet Works
- FlexNet transmitters collect meter consumption and status information and communicate that data to the TGBs
- The TGB forwards data to the RNI via standard telecommunications, but stores data in the event of communication interruption
- Once data reaches the RNI, a utility is able to perform billing, account management, network management, data warehousing and customer hand-off functions based on the information received
Two-way FlexNet Features for Electric Utilities:
2 watts of 900 MHz licensed power output
Programmable daily, hourly, 15 and 5-minute data intervals
Time-of-use billing
Remote Disconnect/ Reconnect
AC Load Shed Transition
CRC-32 protected, redundant data messages
Tamper and energy theft detection
Under the glass integration of electric meters
Programmable Power Fail notification
Programmable momentary outage notification
Programmable low voltage detection
Hot Socket Detection
Programmable thermostat that allows two-way communications between utility and customer
Meter location using poll command
Demand reads and demand register reset commands
Both simple residential and advanced C&I applications with a single network
ANSI Table sessions (virtual modem)
One-way FlexNet Features for Gas Utilities:
2 watts of 900 MHz licensed power output
Hourly or daily reading options
Flexible programming options
CRC-32 protected, redundant data messages
20 year battery life
Both residential and C&I Meters
Multiple Meter Compatibility
1.2Sensus Electricity Metering Solutions
The iCon electricity meter, a solid-state electronic meter with a patented, mutual inductor-sensing technology that provides the most accurate and reliable technique for measuring electricity throughout the entire operating life of the meter (with the inherent advantages of electronic solid state meter technology) as well as a modular mechanical meter design, was developed specifically for easy integration of AMR/AMI communication applications.
While proving this technology to the market by delivering over a million iCon meters to date, Sensus pursued a parallel strategy of establishing our AMR/AMI communications and information based solution. The AMR/AMI communications and information strategy is accomplished with the purchase of Advanced Metering Data Systems (AMDS). As a technology and service provider, AMDS brought experience and expertise unparalleled in the industry.
The iCon meter’s two-board design features a second board for the display with plenty of real estate for communication technology.Since the metered data is stored on the main board, the display board can be easily and quickly replaced in the field, without interrupting the metering values.More importantly, this design will protect investment with future flexibility while maintaining metering integrity.
The iCon meter family of meters features a truly solid state design that does not accumulate pulses but is a direct read of energy from the metrology platform. The meters information is directly available visually from the display.
1.2.1Electricity Meter Interval Data
The FlexNet system delivers interval data utilizing the system to read electricity, water and gas endpoints.C&I meters are supported in their native resolution, where data is then accessed through the use of the included C12.19 tables.The residential Icon electric meters that are equipped with the FlexNet modules can measure energy in intervals of 5, 15, 60, 360 (6 hours) 720 (12 hours) and 1440 (24 hours) minutes, which is programmable through the network. This measurement time is based upon a real time clock in the radio module. The real-time clock is synchronized to within one minute of NIST utilizing a time-sync transmission from the tower. The iCon meter is equipped with sufficient memory to store 30 days of two channel data in non-volatile memory storage.
All interval data is gathered directly from the endpoints and populated into the SQL database for later aggregation for measurements.
1.2.2Electricity Meter Home Area Network (HAN) Interface
The FlexNet communication can be extended to the HAN. This has many advantages; particularly that it is the same frequency protection afforded the communication to the meters themselves.The sensitivity and the ability to overcome greater impediments than other technologies also aids in the use of the FlexNet radio. Devices that have been demonstrated with the FlexNet embedded radio are an in home display and a smart thermostat.
The FlexNet system allows for communication internal to a location via a local HAN.There are currently two different HAN systems under evaluation: A ZigBee HAN and all FlexNet HAN. The ZigBee solution has been requested by several customers in the belief that the common architecture lends itself to greater acceptance while the FlexNet-equipped in-home devices offer greater communication capabilities while utilizing the primary-use, licensed frequency that the other endpoints use.
The Sensus in-home network consists of ZigBee Gateway under glass in the Sensus meter that communicates with both ZigBee-enabled thermostats and ZigBee-enabled displays.
Control of the in-home network is facilitated by Sensus application software that interfaces with a Sensus network. The Sensus software communicates via the TGB to a Sensus meter using the Sensus FlexNet RF link over a licensed RF band. The Sensus Meter’s FlexNet processor will pass on any ZigBee-network related information to the ZigBee Gateway (also located in the Sensus AP electric meter), or the Meter Gateway. The Gateway examines the message and either responds with the requested information, or forwards the information to the thermostat or display via the ZigBee RF link.
If the thermostat or display has a response that is sent to the Gateway that should be forwarded to the Sensus application, then the Gateway will forward the message to the Sensus application via the Sensus FlexNet RF link.
Figure 4-1: Sensus In-home Network
1.2.3Electricity Meter Service Disconnect Relay
The iCon FlexNet meter supports a 200-amp, integrated under-the-cover connect/disconnect/load-limitation capability both the iCon A and iCon AP meters support this functionality. The units are capable of sensing the voltage on the load side of the circuit and react based upon programming to the situation.When the disconnect switch is in the open mode, the meter is still capable of detecting and reporting voltage on the load side.The switch is rated at 200 amps and capable to handle 200 amps for limited periods and 160 amps continuous.
Electricity Meter Nodal Capability
All electricitytwo-way devices are capable of relaying a message from a nearby communication module (any that communicates via the FlexNet protocol which would include water and gas meters).This relaying of messages is referred to as “Buddy.” The Buddy system is a stateless relay—once a relaying endpoint has repeated the message it retains no knowledge.This stateless relaying mechanism allows for a continuously self-healing system in which no single element is capable of stopping communication to the endpoint.
Endpoint configuration is managed through multiple approaches.On a manual basis, endpoints can be configured through the web interface either individually or through a batch request. Meters may also be configured through the new meter life cycle management system due to be available Q1 of 2008. The configuration of the TGB’s is performed through menu interfaces on the TGB itself, which is accessible either remotely or via direct connect at the TGB.
1.2.4Electricity Meter Outage Notification/Restoration
The FlexNet system provides a great deal of flexibility in dealing with the determination of an outage vs. a momentary outage.
Initially upon the detection of a loss of power the module will wait a programmable amount of time, up to 120 seconds, prior to declaring an outage and transmitting an outage alarm.Once an outage timeout occurs, the meter sends 4 power fail alarm messages using energy from an on-board storage capacitor, if power is restored prior to the timeout, no alarm is forwarded to the RNI
During the time which the outage has started and prior to the timeout any momentary restoration of power is counted and stored as a ‘click’ count.The click count represents the number of times the breaker up-line from the meter opens and re-closes.The click count duration is also programmable and defined as number of cycles i.e. a ‘click’ may be defined as 2 cycles of 60 Hz power
The ‘click’ count is available in the database for further examination as required by the utility.Should power not be restored prior to the timeout, an alarm message is sent to the RNI.This alarm is then available in the database and also as part of the JMS stream which may be subscribed to and utilized as real time data by various systems in the utility
Power restoration is similar to power failure in that the meter waits a programmable amount of time before determining power has been restored
This prevents false indications of power restoration when only momentary restoration has occurred
Once power has been restored a series of 4 randomly time-dithered alarm messages are sent to the RNI.This alarm is then available in the database and also as part of the JMS stream which may be subscribed to and utilized as real time data by various systems in the utility
FlexNet meters provide an individually programmable register that represents a 0-to-120 second hold-off time before transmitting a power outage notification. The actual voltage is also programmable to provide a low voltage warning. After the hold-off time is reached the Meter Module transmits a sequence of messages over several minutes to reduce the occasions of data collisions.
First power fail transmission 0 to 60 seconds (time randomized in 50 ms slots)
Second power fail transmission 0-120 seconds after the first (time randomized in 50 ms slots)
Third power fail transmission 0-180 seconds after the second (time randomized in 50 ms slots)
Figure 4.2 illustrates the expected performance of the outage reporting capability of the FlexNet solution (the picture can be cut-and-pasted into a new document to expand and view).
Figure 4-2: Outage & Restoral Reporting Capability
1.2.5Electricity Meter Power Quality Reporting
Residential FlexNet meter provide voltage monitoring and alarming based upon outage and sag. Should a meter lose power, an autonomous alarm is generated and gathered by the FlexNet network. Voltage quality is monitored and sampled over a controllable period of time of 1, 6, 12 or 24 hours. The values of average, minimum and maximum over the sample period are provided. Current and harmonic data may be obtained from C&I meters through direct access to the C12.19 tables that contain the information.
1.2.6Electricity Meter Compatibility
The following table provides an overview of Sensus electricity meter integration by Manufacturer:
Figure 4-3: Meter Integration by Manufacturer
1.2.7Electricity Meter Remote Programmability
The FlexNet system fully supports the download of new, executable software to all elements of the network including the endpoints. Changes to software and set points is acknowledged and reported to the data collection system.Additionally, the current settings for all endpoints are periodically sent to the data collection system autonomously.
The control system for meter executable modification is now being developed to allow for scheduling, as well as interruption and resumption of processing.As each module receives the new code it verifies that it has the complete set and if not requests the individual blocks that are missing.Once the code has been fully downloaded to the devices they are verified and marked as ready.The endpoints then await a switch over command before switching to the new set of code.The old code remains in place until the next generation of code is sent to the module.
The modules themselves will retain much of their profile prior to switch over to ensure continuity of service to the given endpoint.This will include metering profile, communication and identification.Should a set of firmware require the restoral to a default set of parameters, this will be contained in the downloaded code.
Endpoint configuration is managed through multiple approaches.On a manual basis endpoints may be configured through the web interface either individually or through a batch request.
1.2.8Electricity Meter Demand (KW) Reading and Reset
Demand meters are reset through a three step process internally to the FlexNet module itself to ensure proper operation:
The meter is first read to obtain the latest information
Upon successful completion of the read a demand reset is sent and upon success an acknowledgement is sent back
After a successful reset the meter is again read to ensure proper operation
1.2.9Electricity Meter Tamper Detection Method
The tamper detection method is sophisticated as it actually measures the impedance of the transformer and the load (home) to verify that a meter has been removed from the socket (pat pending). Should a meter be removed from the socket while energized a tamper flag is set and an alarm message is transmitted to the head end.The data is then populated into the database for later extraction or is available from the JMS stream.
1.2.10Electricity Meter Diagnostics and Status
The iCon residential meter continuously performs diagnostic tests to ensure proper operation.The results of these tests are stored as health status information in an internal register of the meter.This status information is included with each consumption message delivered by the FlexNet system.Meter diagnostics available for the iCon meter are;
7759 Calibration error,
7759 register check error,
7759 reset error,
RAM bit error,
General CRC error,
Soft EEPROM error,
Watchdog restart,
7759 bit checksum error,
Soft kWh error, data ok,
Low AC Volts,
Current too high,
Power failure,
Hard EEPROM error,
Hard kWh error, data lost,
Configuration error,
Reverse power
The advanced iCon AP single phase and iCon APX three-phase meters also perform diagnostic tests on a continuous basis to ensure proper meter operation.The results of these tests are those flags that are available with C12.19 tables as well as the health status flags available from the residential iCon platform of meters.