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The smart utility’s guide to choosing a smart meter

Intelligent Utilitie, Kathleen Wolf Davis | Apr 22, 2014

 

By Jeff Richardson

Not all smart meters are created equal, and because metering products, marketplace requirements and best practices vary widely around the world, making the best metering choices can be difficult. For North American utilities (U.S., Canada, Mexico, Central America and the Caribbean), this article was written to help answer the question “Which meter is best for me?”

Safety first

1. Look for a meter with a service switch that cannot be left in an indeterminate state, a system that identifies the status of the switch and a sensor that can report whether load-side voltage is present. If your customer is using a backup generator during a major power outage and the switch suddenly closes in to the independently energized circuit, the result could be irreparable physical damage.
2. Smart meters equipped with a surface-mounted button for operating the load break switch may seem like a great idea. It’s best, however, if your meters don’t have them. Requiring customers to interact with the meter is unnecessary and potentially unsafe.
3. Some meters incorporate blades that can slightly adjust their alignment. This makes them better able to make a solid connection with a less-than-perfect socket, a condition that might generate excess heat.
4. Secure connections are essential to safe operation. Open the meter and compare the way in which its components are secured, especially the strength of the connections in the primary current path.

Accuracy and reliability above all

1. Most smart meters have a failure rate of approximately 0.5%. Some have surpassed this, achieving a failure rate of 0.3% and, in some cases, as low as 0.2%. Select one of these.
2. Resolution also varies, from as low as 8 bits to as much as 21. Resolution is important to measurement precision, i.e., the ability to achieve accuracy reliably.
3. Some smart meters use batteries to keep time across a power outage. The use of a supercapacitor can either prolong battery life or reduce the need for a battery. Some smart meter designs don’t require a battery. Find out what your meter uses and why.
4. The meter is the cash register. Your meter shouldn’t sacrifice measurement accuracy or precision for the sake of convenience. Choose one that performs all functions and stores data in the meter itself, not in the communications module. They are more accurate and easier to audit.
5. Anomalies sometimes occur in interval data due to events such as power outages and clock adjustments. Choose a meter that is able to identify and report these anomalies so that the data can be correctly interpreted. This will improve accuracy and billing verification.

Reliable performance

1. Opaque plastic covers or housings significantly reduce thermal gain and internal heating, improving accuracy and extending the life of the meter.
2. While all meters used in the U.S. must meet the ANSI standard, only some exceed it. Look for a meter that’s been subjected to additional engineering and manufacturing tests designed to guarantee even greater accuracy and reliability.

Extended life expectancy

1. Meter failure rates tend to follow a “bathtub” curve -- they’re highest immediately following deployment and at the end of their normal life expectancy. Ask about a meter’s longevity, and check the manufacturer’s warranty and return rates.
2. Technology is changing rapidly; you want a meter that can be readily and remotely modified or upgraded. Look for a vendor whose newer firmware for metrology and communications is downloadable to current hardware.
3. Look for a meter that has fewer or smaller openings in the base. Openings can let in water or insects that may cause damage to the meter.

Minimal environmental impact

1. Choose meters that snap together. They’re easier to disassemble and easier to recycle or repurpose.
2. Some meter manufacturers use common components across their product line, leveraging surplus materials from one product by employing them in a different product. This reduces waste and meter production costs.
3. Some manufacturers have decreased the amount of energy used by their meters. Thus, they’ve also lowered the meter’s internal temperature (improving safety and reliability) and reduced parasitic load (lowering operating costs).

Beyond traditional metering

The smart meter ROI continues to grow and now includes applications extending beyond traditional revenue billing. For example, meters and meter communications are now being used as distribution voltage sensors for outage and restoration management, as well as for connectivity to distribution network edge devices. To support emerging applications, the following features are important.
1. Accurate and flexible voltage monitoring. Meters must measure voltage accurately and should detect changes using programmable thresholds with event logging and notification. Voltage profiling stored in the meter’s nonvolatile memory is essential for post-event analysis.
2. Meters need communication flexibility to allow transport of appropriate messages based on the application. They should also offer the ability to be remotely and securely reprogrammed, especially for communications capability and protocols.
3. Meters and metering communications modules must support robust data security capabilities, including encryption and segregation of differing types of data traffic.
All meters are not created equal. Buyer beware. And be smart.

ABOUT THE AUTHOR:

Jeff Richardson is senior product manager - electricity metering with Elster Solutions and responsible for Elster’s electricity metering product line. He has served on several industry technical committees, including the ANSI communication protocol committee and Measurement Canada joint working groups on firmware updates and VA calculation methods. Jeff has worked on metering and utility solutions in Canada and the United States since 1991. He played a key role in the success of the Ontario Smart Metering Initiative, the world’s largest deployment with daily interval data reads from every meter. Jeff holds an engineering degree from the University of Toronto, and is registered as a professional engineer in the province of Ontario.