Excellent wireline and wireless solutions exist for all utility sectors, but cost, security, and usability considerations may render them redundant or logistically difficult to manage when implemented as separate systems. Both may result in network infrastructures that are at best inefficient, or at worst too costly for large-scale deployment. This article outlines a way to leverage electricity metering infrastructure to perform gas and water metering at a low marginal cost.
The global communications phenomenon has clearly taken hold in the AMR industry. Now meters of all kinds can benefit from longer-range and more cost-effective data connections than ever before. This means utility companies have the potential to install systems that read meters from anywhere at any time. Most often, data collection and maintenance of remote fixed networks can be automated through the use of intelligent two-way communications. Utility personnel and contractors can read individual meter data without leaving the office, and can easily check up on network status and receive automatic alerts in case of anomalies such as leakage, tampering, backflow and low battery (if battery operated). Part of the improvement in the AMR network chain comes from the increased use of GSM SMS-GPRS services. This new wireless machine-to-machine (M2M) technology complements wireline PSTN networks (regular and high-speed WAN/Internet connections) to get data from the field back to the utility office when using a fixed network topology.
Figure 1: Re-use existing gateways to bundle water, gas, heat
and electric metering services using ultra low power RF technology
Wireless metering solutions have also made significant progress, with continuous improvements in long-life battery-powered meter monitors and associated network devices that can relay data from apartment complexes and other commercial and industrial environments via various concentrator units and gateways. Such solutions are particularly applicable to AMR for water utilities, where electrical wiring or cabling to water meters is a costly option, and for gas meters where electrical cabling is not safe.
At the same time, electricity meters often benefit from high levels of AMR connectivity. This is due at least in part to the meters’ access to a power supply for external data connections, such as via the cellular telephone network or other WAN installation. In addition, electricity meters that are connected to each other in local networks (LAN) via power line carrier (PLC), serial links (RS485, RS422…), or even twisted pair (TP) can benefit from efficient use of fewer gateway devices to reach the outside world.
Given that electricity meters are usually installed with remote AMR solutions before water or gas meters, wouldn’t it make sense to be able to take advantage of that infrastructure to add remote AMR solutions for the other types of nearby utility meters?
WHY INSTALL SEPARATE AMR NETWORKS AT THE SAME SITE?
Vendors of ultra low-power (ULP) wireless AMR solutions have encountered this situation many times. Customers have a connected electricity metering solution, and look for a gas and/or water AMR solution to offer new global added-value services. Clearly, the individual meter monitors still have to be installed for the different utility types, but there is an easy way to avoid redundancy of costly gateway equipment and to benefit from the existing electricity AMR system with very little additional cost.
The solution is to enhance the connected electricity meters with the necessary technology to act as a bridge between a wireless gas and/or water AMR network and the outside world. This would most likely be provided as under-glass integration in electricity meters that already embed a WAN gateway (PSTN, GSM). In this scenario, you would equip the non-electricity meters with wireless monitoring devices, and build the most appropriate wireless network for the premises.
Among the network equipment would be repeater devices, or meter monitor nodes with a built-in capability to forward data from the most remote meters. Today, wireless AMR solutions exist that offer an intervention-free lifespan of 10-15 years, and allow you to build wireless unlimited in size using mesh network topology for easy installation and maintenance. The lifespan/power consumption ratio is optimised with respect to the relatively low volumes of data traffic from individual meters, which should not overload the existing network connection. (On average a meter that transmits data once a day can be expected to last 15 years in the field).
In addition the wireless router for the water and/or gas AMR system can benefit from the power supply available to the electricity meter, and thereby alleviate the battery constraints for that business-critical piece of the network puzzle. A properly implemented wireless network will also help you avoid costly cable-laying issues.
EFFECTIVE WIRELESS SOLUTIONS FOR AMR IN A PIGGY-BACK NETWORK
Connecting electricity meters is technically no problem, as they are by definition already connected by PLC links, and possibly by serial or even wireless links of their own. Gas meters, on the other hand, should not be cabled with live electric wiring! Therefore a purely wireless solution is best for gas, and is certainly a proven efficient choice for water meters and heat cost allocators (HCA) monitoring systems.
In order to gather meter data from geographical zones of different densities – sometimes high-rise apartment buildings, sometimes sprawling suburban neighbourhoods – it is necessary to use a radio frequency (RF) technology that meets a fairly strict list of requirements. For example, due to harsh conditions and out-of-the-way placement of utility meters, wireless AMR requires an RF solution that is highly resistant to obstacles (not to mention over-the-air activity from potentially hundreds or thousands of network nodes) and can offer long enough range coverage that the need for dedicated repeaters is minimised. Since utility companies are implementing AMR to improve efficiency and service quality in the first place, the solution has to offer both a high level of reliability and two-way communications for anytime reading, alert notification, and remote maintenance.
Wireless network technology has indeed made a lot of progress over the past few years, and now offers simplified (if not fully automated) installation procedures that save time and money in the field, as well as the ability to support nearly any requirements for residential and C&I settings – including features such as point-to-point, point-to-multipoint (broadcast, polling) and integrated repeater operating modes in star, tree, and mesh network topologies. When all these conditions are met and accompanied by low per-unit cost and ultra-low power consumption, the task of forwarding data to the electrical meter gateway(s) is not a difficult one. From there it is a relatively straightforward matter to leverage the proliferation of cellular network and other WAN solutions to get data from the field back to the utility office automatically.
The missing link for combined gas, water, and electric metering may already be in place. Now it’s just going to be a matter of implementing the tools to take advantage of it.