Top Design Considerations for Low-Power Metering Applications

As green energy management becomes a global imperative, the idea of implementing intelligent systems and wireless technology to more efficiently use energy and other natural resources has become a pervasive reality. It began with a relatively simple idea. If you add embedded intelligence and a communications link to a traditional metering device, you have the ability to remotely access the data that the “smart meter” has collected.

Multiple forms of energy are monitored and controlled in the energy metering ecosystem, including gas, water, electricity and thermal energy. Metering information from a group of residential, commercial and industrial facilities is typically sampled at regular intervals and aggregated by a common metering collector before being sent to the service provider.

Primary utility meter types

In the very broadest sense, there are three distinct categories of metering devices. The most common is the electricity meter, which quantifies the consumption of electrical energy.

With respect to electricity meters, functionality can be split into two functional areas: the metrology or measurement function and the communications subsystem. The requirements for the metrology function vary by region and meter type (residential versus industrial), with some of the variables including the number of phases being measured, the accuracy of the measurement, the requirement for different rates dependent on time of use and the level of security required at the communication layer.

Primary utility meter types

In the very broadest sense, there are three distinct categories of metering devices. The most common is the electricity meter, which quantifies the consumption of electrical energy. The second most common is a meter that measures the consumption of a fluid, such as water, natural gas, or fuel oil.

With respect to electricity meters, functionality can be split into two functional areas: the metrology or measurement function and the communications subsystem.

Metering functions
With those basic categories in mind, nearly every type of meter has to provide one or more of the following functions:

• Quantitative measurement: This varies by meter type, but the primary function of any meter is to accurately measure a quantity of something. These measurement systems span a wide range of topologies. Some examples include, but are not limited to: temperature sensors, flow sensors, shunt resistors, isolation transformers, current transformers and time-keeping systems.

• Control and calibration: This also varies by type of meter and is typically needed to compensate for small variations in the measurement system. These systems can also perform functions such as tamper resistance and interruption of service.

• Communications: This can be used to configure parameters in the meter and transfer stored data to a host via wired or wireless connection. It can also be used to update the firmware or other operational characteristics of the meter.

• Power management: Low power and system robustness are needed in the event of a primary source of energy going down. In nonelectric metering applications, power management is critical to minimize power consumption and maximize the battery service interval.

• Display: Interfaces to low-cost and low-power LCD and LED displays in seven-segment, alphanumeric, or matrix format are very common user interfaces. In many cases, there is a regulatory requirement that a customer must have the ability to view the billable quantity directly from the meter.

• Synchronization: Timing synchronization is critical for the reliable transmission of data to central hub or other collector systems to support functions such as data analysis and accurate billing. This is particularly needed in a wireless network that has an unpredictable or asynchronous communication protocol.


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