By default, the eGauge will record Power registers as the "Net" (=) subtype. This means the register will record power flow in both directions. Positive readings will be graphed as a green line, and negative readings as a red line.
However, it is possible to record other subtypes as well. Some of these are needed for basic calculations (such as positive-only subtypes) while others can be used in advanced calculations (the apparent power subtype). The full list is below:
- net (=) - Records both positive and negative power readings. Default, recommended setting for all power registers.
- positive-only (+) - Records only positive values. Negative values are converted to zeros. Cannot be selected at the same time as negative-only (-).
- negative-only (-) - Records only negative values. Positive values are converted to zeros. Cannot be selected at the same time as positive-only (+).
- absolute (|) - Records both positive and negative values as positive numbers. Ignores sign.
- apparent (*) - Records apparent power (VA), does not take power factor into account.
Power Register Subtypes
To select a power register subtype, click the small box containing the "=" sign that appears to the right of the "P" indicating a power register. Select the appropriate subtypes and click the OK button. Subtypes are named based on the original (net) power register's name and their subtype sign. For example, a power register named "Grid" recording net, apparent, and positive-only power would exist as "Grid", "Grid*", and "Grid+". Each subtype selection uses an additional register in the eGauge database.
Grid Register with Multiple Subtypes
As with all physical registers, additional registers recording power register subtypes will only start recording from the time they are created.