The performance of meters in service has a direct impact on the power utility’s bottom line. However, achieving a healthy revenue status can only be attained by having an effective metering strategy – but where do you start?

A meter is the cash register for any utility and all the revenue collected can only be accounted for through this humble asset. It is, therefore, pertinent that utilities and municipalities have the right metering strategy to deliver dependable and sustainable revenue.

This article first appeared in ESI Africa Issue 3-2019.
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The secret behind having a versatile metering strategy is not only in selecting the right product but also in carrying out due diligence and choosing the right technical partner. These two attributes, which are the key elements to implementing sustainable metering solutions, are explained in this article.

Selecting the right technical partner

The old electromechanical meter was an essential gadget that did not require indepth technical skills for fault diagnosis and repair. However, with the migration to advanced electronic technology in metering, meters have become sophisticated gadgets, which need specific technical skills along with specialised equipment and after-sales support.

Plus, for the advanced metering infrastructure of today, most utilities do not have the in-house skills required for proper maintenance and support of the electronic meters deployed. There is, however, a need to upskill local engineers to understand the basic principles of designing a smart meter in line with the DTI requirements for localisation in terms of manufacturing in South Africa.

Local-meter manufacturers can customise designs to local conditions such as for surge immunity where international models are based on standards that are not necessarily adequate for African utilities where there is high lightning activity. Support for local manufacturers, where they exist, is also beneficial for the economy at large through employment creation. As such, many utilities have a policy that makes it mandatory for meter manufacturers to have a certain percentage of local value addition.

Selecting the right product

In a world full of fake and pirated products, the quality of technical specifications used for tendering purposes will determine the quality of meters and associated material that a utility can acquire.

It is a daunting task to pinpoint and set the best specifications required, and where utilities find it challenging the consequences are dire. For example, the acquisition of inferior or inadequate meters, which expose the utility to technical and non-technical revenue leakage, can lead to revenue loss.

A well-thought-out meter specification takes into account business requirements and potential risk exposure for the utility. Potential threats include issues such as level of non-technical losses, level of debt, and climatic conditions.

Common to most meters are the rated levels of performance where some of the more universal performance metrics include: accuracy, precision or repeatability, resolution, ease of installation, on-going operations and maintenance, and costs. Here follows an overview of each performance metric:

Accuracy

In terms of accuracy, this performance metric is the difference between a measured value and the actual value. No meter is 100% accurate and tighter accuracy requirements are typically more expensive to procure and may also be more restrictive to specific applications.

Accuracy may be stated in different ways; for example: Class 1, Class 0.5, Class 0.2, Class 0.5S, and Class 0.2S. Note that in these examples, classes 1, 0.5 and 0.2 are percentages of scale, whereas classes 0.5S and 0.2S are quoted as a percentage of reading.

Figure 1 illustrates the difference in reading error between accuracy stated as a percentage of reading and percentage of scale. Within the realm of electric meters, there are multiple accuracy classes for electric meters defined by IEC standards. The selection of accuracy level is determined by the capacity of energy metered and other contractual and legal requirements.

Precision or repeatability

The precision or repeatability of a measurement entails the ability to reproduce the same value (e.g. voltage, power or current) with multiple measurements of the same parameter, under the same conditions. Resolution The resolution is the smallest increment of energy consumption or flow that can be incrementally registered by the meter. For example, the theoretical resolution of a 2,000-count meter with a 3½-digit display is (1/2,000) (100%) = 0.05%. The higher the resolution, the higher the accuracy.

Ease of installation

Here the make-and-model selection criteria consider the size and weight constraints, specific electrical and communications needs, and the overall environment in which the meter will operate.

Ongoing operations and maintenance

The lowest cost metering technology may not be the best choice if it has high associated maintenance costs (e.g. frequent service, calibration and recalibration). A recommendation for decision making, as with most capital purchases, is a life-cycle cost approach (including all capital and recurring costs).

Installation versus capital cost

In some situations, the cost to install a meter can be higher than the capital cost; this can be true where system shutdowns are necessary for meter installations, or where significant redesign efforts are needed to accommodate a meter’s physical size, weight, or required connection. In these circumstances, it may be necessary to consider alternative technologies that may have a higher capital cost but a much lower installation cost.

Utilities need to select the right technical partner and product as well as invest in technological know-how to counter the challenges in reducing losses, increasing revenue collection and reducing downtime. ESI

About the company

Nyamezela Metering is a 100% Black Woman Owned Company, established in 2012 as a meter manufacturer and metering solutions firm. Our main objective is to provide metering hardware and services to utilities, municipalities and the private sector.

www.nyamezela.co.za | info@nyamezela.co.za