It’s tough to argue with the basic idea behind standardized metrology. If presented with identical inputs, two standard instruments with the same specs ought to produce exactly the same results within their margin of error. It would be hard to imagine things any other way for applications like watt hour meters which accumulate energy usage for billing purposes.

However as the allowable margin of error decreases the governing standards must set out greater and greater detail of precisely how the measurement is to be done in both hardware and data analysis. If you happen to be a vendor of such instruments, this leaves you little room for product differentiation and instead the battleground becomes highly efficient design, squeezing out manufacturing cost and carving out market share.

This is not to say that making standard instruments is straightforward, easy or not worth doing because that’s definitely not the case. It’s just not likely to be an entrepreneurial business.

At the other end of the spectrum, there are also complex standards which govern high end power quality instruments with 4-figure price tags. Perhaps the most notorious of these is IEC 61000-4-30 which contains some downright arcane concepts. For example, the diagram labeled, “Figure 2 – Synchronization of Aggregation Intervals for Class A” is taken directly from page 15 of Edition 2.0 of the standard. What this chart describes is how every single sample taken by the voltage channels of a Class A compliant instrument (from the time it’s turned on until the time it’s turned off) get “stacked up” or aggregated into a series of GPS clock-aligned RMS values. It’s not that these RMS values are fundamentally superior to others assembled by more conventional means. It’s just that if you want to build an instrument that complies with the Class A requirements of this standard this is how it must be done. And if you intend to sell a power quality instrument in Europe or China you won’t get in the customer’s door if it doesn’t comply with 61000-4-30 Class A.

Another common issue that arises from standards-based metrology is that instrument users are often unaware of how difficult it is or what it actually costs them. Often the listing of standards to be met in procurement documents substitutes for critical thinking of what is actually necessary.

If you think about the above aggregation example, it’s clear this is not something that is workable in a low power environment. Normally getting sufficient power to run a power quality instrument isn’t a big deal – just take it from the AC line. But suppose you’re building a battery or current-induction powered instrument – you simply won’t be able to do what the customer assumes is the baseline level of metrology demanded by a lengthy list of standards which they don’t really understand.

Successfully navigating the development landscape when standards are involved requires deep technical and market understanding plus significant experience. This is where DJA Engineering can really help.

Areas of Expertise

DJA provides a broad range of engineering services from technical consulting to full design/testing of AC power measurement systems operating at voltages from 120V to 35KV. We help get your power metrology job done cost-effectively with a wealth of knowledge in the following areas:
We are experts using modern digital sampling techniques with both time and frequency domain data analysis methods for the full range of home/commercial/professional applications. [learn more]
Current/voltage transducers are a necessary evil and we understand how to identify the best ones for every job. We also have particular expertise in Rogowski coil current sensors. [learn more]
Extracting what one needs to understand from standards is rarely easy and some important ones are downright daunting. We have a broad understanding of the applicable standards and can help navigate the best path through the maze. [learn more]
Safety must be designed into every power metrology product and assurance is a big deal, especially for high voltage electric utility equipment. We are also experts at making best use of expensive external labs. [learn more]
Neutral, third party evaluation of the methods used and data being delivered by newer SmartGrid instruments can streamline procurements, expedite trials and maybe even avoid legal bills. [learn more]
We have deep experience with both narrow and broad band PLC technology can make it work for you when that makes sense or make sure you avoid it when it doesn’t. [learn more]
We have a collection of reference instruments and intimate knowledge of the tricks of the trade. We can work with you in depth or provide just the specific answers you need for your project. [learn more]