Increasing recording time at a short registration periods is a well-known issue in power quality analysis. Metrel offers two solutions to optimize this issue as follows:

- auto recorder restart,

- two pre-defined integrated recording profiles.


Auto recorder restart

Since users are usually interested in a large number of monitoring registers, we have decided not to limit the number of recorded registers and offer users selectable recording periods (custom time interval from 1 second to 2 hours), though without sacrificing the number of registers (even at 1 second interval).

Recording sessions with a registration period of 1 second usually generate huge files (up to a few GB), causing issues with largest supported file size in FAT32 (microSD are formatted to that file system). To mitigate this, an auto recorder restart is implemented in models MI 2893 Power Master XT, MI 2892 Power Master and MI 2885 Master Q4. In other words, when recorder stops due to reaching the maximum available length (set at 1.666 GB), it will automatically start a new recording period.

To enable auto recorder, “Manual” should be set under “Duration” as shown in example picture below:


In this manner a single microSD card with a capacity of 7.566 GB (nominal 8 GB) can save 4 entire recording sessions (each 12 hours long) and an additional 6 hours (all together 4x12 hours + 6 hours, i.e. 2 days and 6 hours of recordings). This approach also works for other time intervals (not just 1 second), maximizing usage of storage capacity on the selected microSD card.


Pre-defined integrated recording profiles

Available are two pre-defined integrated recording profiles:

- Standard profile,

- Limited profile.

The Standard profile includes all recorded measurements (approx. 5220 registers). It is suitable for most PQA application.

Limited profile includes only a limited set (most important ones) of measurements (approx. 1220 registers) and is most suitable for long term recording with a short interval (1 week long record with a 1 second interval).

Main differences between the Standard and Limited profile:

- Limited profile registers only average (AVRG) values for P, Q, S, energy and harmonics, while the Standard profile also registers MIN, MAX, AVRGON values.

- Limited profile doesn’t register 10 s frequency values and interharmonics.


Overview of recording duration for different interval period in comparison with profile selection is shown on picture below: