Technology has transformed the electric utility industry forever in many ways. Utility meters in the past required inspectors, building owners, or building managers to manually read off the face of meters at a property once a month or every quarter. They would then compare it to a reading from the previous period to process an invoice for the utility services used. Today, new remote meter reading technologies have become common replacing traditional manual reading meters.
Manual vs. Pulse Reading Utility Meters
Traditional manual meters still do exist in some commercial buildings. They are usually locked in the basement, and the meters display energy consumption on a screen. They don’t transfer data back to building owners, managers, or engineers. To record the energy consumption, they need to physically go to the location to read the meter.
With advancement, manual meters were improved to produce a pulse. A pulse was counted by a pulse counter that would release the count at the end of a specified period. One pulse could represent a known quantity. The pulse counter (data logger) would release the total pulse count (RFID technology or external wand) and reset itself for the next period count. Pulse output meters combined with data loggers are capable of relaying data into an analytics platform.
Wireless Metering Solutions
Today, utilities are moving to wireless transmission of data by utilizing smart meters with different types of wireless transmission protocols, such as:
Advanced Metering Infrastructure (AMI)
AMI as defined by the US department of Energy is an integrated system of smart meters, communications networks, and data management systems that enables two-way communication between utilities and customers. The applications in AMI provide the ability to automatically and remotely measure electricity use, that is read the meter, connect and disconnect service through the meter, detect tampering, identify and isolate outages, and monitor voltage. All these functions were not possible in the days of manual reading and provide huge improvement as the communication is bidirectional, and not jus passive as in the case of pulse output collection. .
Automated Metering Reading (AMR)
AMR as its name implies is the technology that automates the process of reading meters and transferring the data to a local database for further processing. By establishing a connection between an energy supplier and a business customer. For these meters, communication is uni-directional – from the customer to the supplier, whether an electricity, water, gas or heat utility. The supplier receives meter reads in real-time allowing billing to take place based on more accurate data. The information gathered from the meter allows customers to analyze their energy usage data.
Sub-metering Communications Technologies
Sub-metering is different from the utility approach because the services as the name implies take place behind the utility meter (Bulk-meter) for the whole building or campus. This approach to metering enriches the information available to the owner, the energy or the property manager, and simplifies the integration of all utility services (electricity, gas, water, heating, and cooling) into a single platform. Like at a utility level sub-metering systems can be Automated and the infrastructure, although a smaller scale, can be deployed just like AMI and the reading process can also be automated.
Because the meters are all in close proximity to each other and the spread of meters, even in a large campus, is reduced when compared to the spread of meters of a state or national utility; It is not as expensive to link these meters into smaller networks that use other more common protocols for communication, discussed below.
Modbus was originally published in 1979 as a serial communications protocol developed with industrial applications in mind. It enables the communication of many devices in the same network, it is easy to maintain and deploy. Openly published and royalty-free, it has become a standard communication protocol for connecting industrial electronic devices. It enables communication among devices connected to the same network.
Among all the protocol versions of Modbus the most commonly used are Modbus RTU (usually over RS485 serial communication) that follows an error check mechanism to ensure the reliability of data; and Modbus TCP/IP is a Modbus variant used for communications over TCP/IP networks, that does not require a checksum calculation like ModBus RTU, as lower layers already provide checksum protection.
BACnet (Building Automation Controls Network) is a network protocol designed to allow communication between building control and automation systems (for applications such as HVAC, ventilating, heating, fire detection, access control, and lighting control systems and their equipment) and their users and manufacturers.
M-Bus or Meter Bus is a European standard for remote reading of electricity, gas, and water meters, M-Bus is usable for other types of consumption meters as well. It was developed to enable remote reading and networking of utility meters. While the wired M-Bus system also uses Serial RS485, it is wired in a single pair, non-polarity sensitive mode where meters are "T" tapped and not daisy chained, making the installation a lot easier to deploy and to troubleshoot. Data can be collected with a hand-held computer, or it can transmit readings via a modem.
With energy consumption data being transmitted via wireless routes, we can read it as frequently as necessary. These protocols can provide additional meter information, so that it can be more than just a collection of data on energy consumption. For example, Voltage, frequency, water temperature and water pressure can also be transmitted in real time to monitor the quality of service. In the case of heating/cooling meters, we can obtain information on the flow, direction, and initial and final temperature to get more data for further analysis that can help us improve the building performance. Other control functions can be implemented, like turning on or off loads or suspending the service.
At the database level and with the right software platform; special tariffs can be added to charge for electricity so the users can pay according to his or her time of use.
Today, almost every building has internet accessibility, so it is easier to gather all meter readings in a central DCU (Data Collection Unit) which acts as a gateway to the cloud where the information is stored and processed. This way owners, property and energy managers can have access to their meter data in real-time and with a greater level of detail and certainty.