Automated voltage measurement: Tradeoff between PLC and averages
If you have 30 powerline cycles available to do the measurement, how do you choose between asking the meter to do few long measurements, and many short measurements?


You have to read the data sheet very carefully, and back that up with actual measurements. If it's a good quality meter, and the designers have done their stuff, you ought to be able to rely on one long reading to provide the best result. But it's possible that that's not the case.

Do some experiments with a sequence of single readings, to understand what the variation is reading to reading with your measurement setup. Characterise the noise. Then repeat with a sequence of multiple readings. Compare. In the process, you're trying to verify the meter specifications, and I'll wager you will learn something about your test system that you hadn't anticipated. I always do!

It may be interesting to see how long it takes to do a single PLC measurement. Set your system up to take (say) 100 measurements. Does it take 100 PLCs, or 110, or 150, or 200? If 100, it's obviously pipelining measurement and reporting. If 110, it's able to time a single cycle from any phase, and not pipelining the report. If 150, sounds like it's going form zero cross to zero cross, but can use either. If 200, it sounds like it's always waiting for a particular polarity of zero cross to sync to. Each strategy has its costs and benefits.