“Power lines were engineered to move energy, not certainty. In smart metering, PLC and BPL fail when the utility discovers that every transformer, every kilometre of wire, and every noisy customer load has a vote in whether the data gets through.” – MJ Martin
The Promise and the Reality
Power line communications, or PLC, sounds attractive for smart metering. Every electric meter is already connected to a wire, so the wire appears to be a ready-made communications network. Broadband over power lines, or BPL, takes the concept further by trying to move higher data rates through the same distribution system. On paper, it looks efficient. In practice, especially in Canada, it often fails the test of distance, reliability, speed, and cost.
The Grid Was Not Built for Data
Electric distribution systems were designed to deliver energy, not clean digital signals. A power line is electrically noisy. Motors, switching power supplies, welders, variable frequency drives, solar inverters, and customer equipment all inject noise back onto the circuit. A smart meter signal may be small compared with the electrical environment around it. Unlike fibre, coaxial cable, or licenced radio, the power grid does not provide a controlled communications path. The channel keeps changing as customer loads turn on and off.
Transformers Become Choke Points
The largest technical problem is the transformer. In most Canadian distribution systems, the meter is on the low voltage side of a transformer, while the utility feeder is on the medium voltage side. Transformers are excellent for changing voltage, but poor for passing high frequency communication signals. They act like filters or choke points. A PLC signal that travels along a secondary service may be blocked, weakened, or distorted at the transformer. To overcome this, utilities often need couplers, bypass devices, repeaters, or collectors. Once that happens, the promise of using the existing power line “for free” begins to disappear.
In Canada, the small number of customers per transformer breaks the economics of the required transformer bypass technology so the cost per customer is very expensive and therefore prohibitive to use. In Europe where they have hundreds of endpoints per large transformers the economics make sense. For example, in Italy you may see 500 or more endpoints per transformer. The 50 hertz, 220 volts makes a difference there too.
Canadian Distance Works Against PLC
Canada makes the problem harder because many utilities serve large territories with low customer density. Rural feeders can be long. Farms, acreages, hamlets, and remote services may be separated by kilometres rather than city blocks. PLC performance declines with distance because the signal attenuates, noise accumulates, and impedance changes from one section of line to another. A technology that may work in a compact urban network can become fragile on a prairie feeder, a northern circuit, or a long radial line.
Data Rate Versus Useful Throughput
BPL once promised broadband-like speeds, but smart metering needs dependable throughput more than theoretical speed. Meter reads, outage pings, voltage data, firmware updates, and event logs must arrive consistently. In utility operations, a slow but reliable network is more valuable than a faster network that drops packets, requires retries, or fails during noisy load conditions. Higher frequencies may support higher data rates, but they also suffer greater attenuation and more sensitivity to line conditions.
Efficacy in Smart Metering
For smart metering, efficacy means daily reads, outage notification, tamper alarms, remote disconnect where applicable, voltage monitoring, and secure two-way communications at scale. PLC and BPL struggle because performance varies by feeder, transformer, customer wiring, season, load profile, and geography. The utility ends up engineering exceptions instead of deploying a repeatable standard.
The Practical Conclusion
PLC is not useless. It can work in short, dense, carefully engineered environments. The problem is that Canada is not one uniform environment. It is urban towers, suburban loops, rural laterals, long feeders, extreme cold, mixed overhead and underground plant, and many transformer configurations. For Canadian smart metering, RF mesh, point-to-multipoint radio, cellular, fibre backhaul, and hybrid AMI systems are usually more practical. PLC and BPL fail when elegant theory meets the physical reality of the Canadian grid.
About the Author:
Michael Martin is the Vice President of Technology with Metercor Inc., a Smart Meter, IoT, and Smart City systems integrator based in Canada. He has more than 40 years of experience in systems design for applications that use broadband networks, optical fibre, wireless, and digital communications technologies. He is a business and technology consultant. He was a senior executive consultant for 15 years with IBM, where he worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He is a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN: TSX).
Martin served on the Board of Directors for TeraGo Inc (TGO: TSX) and on the Board of Directors for Avante Logixx Inc. (XX: TSX.V). He has served as a Member, SCC ISO-IEC JTC 1/SC-41 – Internet of Things and related technologies, ISO – International Organization for Standardization, and as a member of the NIST SP 500-325 Fog Computing Conceptual Model, National Institute of Standards and Technology. He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) [now Ontario Tech University] and on the Board of Advisers of five different Colleges in Ontario – Centennial College, Humber College, George Brown College, Durham College, Ryerson Polytechnic University [now Toronto Metropolitan University]. For 16 years he served on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section.
He holds three master’s degrees – in business (MBA), communication (MA), and education (MEd). As well, he has three undergraduate diplomas and seven major certifications in business, computer programming, internetworking, project management, media, photography, and communication technology. He has completed over 80 next generation MOOC (Massive Open Online Courses) [aka Micro Learning] continuous education programs in a wide variety of topics, including: Economics, Python Programming, Internet of Things, Cloud, Artificial Intelligence and Cognitive systems, Blockchain, Agile, Power BI, Big Data, Design Thinking, Security, Indigenous Canada awareness, and more.
Martin in a volunteer, a photographer, a learner, a technologist, a philosophizer, and a romantic optimist.