Test & Measurement
Boosting energy efficiency through accurate power measurement
There is also a need to carry out
Energy efficiency requires standards and ensuring compliance requires accurate measurement. Hafeez Najumudeen looks at how developments in digital power meters will help the industry to achieve this
M
anufacturers of electrical equipment – whether for industrial use or for the domestic
appliance market - are increasingly focusing their efforts on energy conservation. This trend is reflected in the growing emphasis on both renewable energy and energy efficiency measures to reduce the amount of energy consumed. Governments and regulatory authorities are establishing new standards for the energy consumption of various types of equipment.
Appliance manufacturers now have to
prove that their products comply with certain IEC/EN standards, for example. Equipment has to meet complex and stringent specifications, and in many cases products have to carry energy efficiency labels to show that they meet these requirements.
Standby power consumption Typical of this trend is the demand for a lower threshold in standby power consumption. This is an important area for a number of reasons. For example, it is estimated that between 5% and 15% of residential electricity used in the OECD countries can be attributed to the power consumption of appliances in standby mode: equivalent to about 240 million tonnes of carbon dioxide emissions every year.
Moreover, by 2020 it is expected that
approximately 4.6 billion products will be featuring a standby option, contributing around 50 TWh of electricity consumption per year. This amount is equal to the total electricity consumption of a country like Greece or Portugal. The International Energy Agency (IEA) has launched a 1 W standby initiative, and it is expected to decrease this threshold to 0.5 W by 2013. The scale of the challenge presented by these limits is illustrated by the fact that 18.5% of all household
10 April 2013
Figure 1: The Yokogawa WT300 Series of digital power meters combine accurate and reliable power measurement over a wide power range with flexibility, ease of use and a choice of communication interfaces
15 TWh. This represents a saving of around 35 TWh of electricity: equivalent to the total electricity consumption of Denmark.
User requirements In order to meet these regulatory requirements, equipment suppliers will need to measure the actual power consumption of their products, often at very low power levels. They obviously require accurate and reliable power measurement over a wide range – from the milliamperes encountered at standby levels to the tens of amperes used in induction hobs, for example. Accuracy and reliability are essential to develop and produce products which not only comply with standards but also guarantee consistency.
Components in Electronics
productivity and enhancing quality assurance.
Digital power meters These challenges are addressed in Yokogawa’s latest generation of digital power meters (Figure.1), which offer a basic accuracy of 0.1% of reading, guaranteed accuracy over the entire measurement range (from 1% to 130%), a wide measurement range from standby power levels of a few milliamperes up to 40 A, and flexibility to enable users to target different technical and commercial applications.
A range of communications interfaces allows these digital power meters to be integrated into laboratory test benches or automated test set-ups on production
appliances in “off” mode and 31% in standby mode failed to comply with the 1 W initiative. The proposed reduction to 0.5 W will result in 41.5% in “off” mode and 66.4% in standby failing to comply. If an item of equipment has power consumption between 0.5 W and 1.0 W, it is estimated that electricity consumption in standby/off mode by 2020 will be about
measurements other than the standard electrical parameters of voltage, current and power, because of the increased regulatory emphasis on power quality which demands measurements in areas such as harmonics and frequency-based parameters.
Equally important, particularly in the
production environment, are ease and flexibility of use, to ensure that employees with all skill levels are able to operate the instruments. Production testing also requires a communications interface so that the measuring instrument can interact with PCs and other instruments to create an automatic test system for improving
lines. USB and GPIB or RS232 is fitted as standard, and Ethernet is available as an option (Figure.2).
In addition to standard power
measurements, these instruments incorporate a wide range of harmonic measurement capabilities, including the ability to carry out simultaneous measurement of normal power parameters such as RMS, mean or DC power along with measurement of harmonics up to the 50th order. As a result, overall measurement times are reduced, allowing users to allocate their effort and time to other tasks. Other features of the new instruments include a bandwidth of DC and 0.5 Hz to 100 kHz (up to 20 kHz for 40 A on the WT310HC), plus an auto-range function for measurement and integration. The guaranteed accuracy of the new power meters results from the fact that Yokogawa has its own European standards laboratory at its European headquarters in The Netherlands. This facility is the only industrial (i.e. non- government or national) organisation to offer traceable power calibration, to national and international standards, at frequencies up to 100 kHz: a requirement for higher harmonic measurements specified in quality standards such as ISO9000. Software is also available for testing equipment compliance to industry energy- saving standards such as IEC62301 Ed2.0 and IEC62018 for standby mode equipment or for dealing with waveforms having a crest factor of 5 or more.
Applications
These digital power meters are suited to a broad range of applications in the production, evaluation and R&D sectors, satisfying a variety of customer needs for AC and DC measurements of voltage, current and power as well as integration and harmonic measurements. Some typical applications are: • Quality assurance and production line testing of electrical devices
• Development and evaluation of domestic appliances
• Evaluation of DC operated devices in automotive applications
• Power consumption and efficiency
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