CLOU energy meters and test equipment is measuring the true RMS value by waveform sampling. There are other methods, but they are less accurate.
With increasing percentage of renewable energy on power generation we will see more disturbances in the grid.
The interactive graphics below shows the impact on sampling rates on different waveforms. The error calculation is based on true-rms for a wave with 360 samples and for training purpose only.
The phase to neutral supply voltage is controlled by the power generation companies and utilities by using transformers with on-load tap changers. Depending on the region you can find different supply voltages.
Electronic meters with build-in relays can serve for various functionalities. By IEC62052-11 Ed.2 the name for this sort of relays is Supply Control Switch (SCS).
Electronic energy meters, especially those with STS payment functions have the ability to give an alarm. Low credit is a typical example.
Electronic energy meters with a build-in load switch can be programmed for a maximum load. If a consumer exceeds the limit, he will be disconnected