As electricity is generated, transmitted, distributed and used, measurements are everywhere for different applications, how similar, how different??

Electrical measurements!!

As electricity is generated, transmitted, distributed and used, measurements are everywhere and for objectives as wide ranging from revenue metering (somebody has to pay for energy used, to somebody who supplied it, in fact measurements for commercial transactions are beyond cumulative and interval energy measurement, they are done by conventional revenue meter or not, is a different question!!), energy audit metering (we need to asses losses in networks), operational metering (electricity being a typical commodity, electrical power system operation is not a simple task, in fact lesser of that now!! check with unenviable job of system operators!!), power quality metering (suitability of commodity i.e. electricity supplied for the applications that are using it), protection metering (system has to safely operate and in case of any faults, protective relaying must operate to clear it, triggered by measurement done by it), disturbance metering (intentionally I say metering to rhyme similarly!! word that we normally use is disturbance records to indicate temporal and more granular nature with objective of analyzing the event and take corrective actions) and finally temporal view of measurement with even some status signals (SoE or sequence of events) and geographical view of the same (wide area measurements).

Above is not an exhaustive list but really these are many typical applications that electrical measurements are used for in a system be it a generation plant, transmission and distribution network, industrial distribution network or domestic usage.

While all involve measurement of electrical parameters (voltage, current, angle and derivatives thereof) but are distinguished in their application as noted and more importantly in peculiarities (or generalities) of measurements therein!! Some measurements may get joined together in single device naturally (most optimum solution e.g. protection metering and SoE, revenue metering and energy audit) or by measurement equipment using a more capable processor (e.g. disturbance recorder and power quality measurements, though costly proposition) or at some compromise to the application (including compromises that we should not do!!). An overenthusiastic salesman proposes you more in one device, nice so far, but we need to be clear that while some compromises are workable, but some are really not!!

There are technical trade-offs, there are compromises based on economics of it and sometimes both but most important are the ones that an ignorant salesman (presumably so!!) doesn’t talk about!!

So, next time when somebody tells you “more in one” device, it may be either of the above cases, wear your hat of somebody using that application and get the person to answer how this meets the typicality of my application of e.g. revenue metering, operational metering, power quality metering, protection metering or time and geographically spread measurements and don't miss, suitability is more than communication protocol, you need to input measurements to an analytical system but least is, measurements have to be as per applications!!