The reactive power sign convention sets which direction of power flow counts as positive. Two systems are common: the generator reference-arrow system and the consumer (load) reference system. In the generator convention, power flowing from the plant into the grid is positive. Active power output is positive and active power drawn from the grid is negative. Positive reactive power means over-excited operation, where current lags voltage and the device injects vars, which tends to raise voltage. Negative reactive power means under-excited operation, where current leads voltage and the device absorbs vars, which tends to lower voltage. In the consumer reference system, current absorbed from the grid is positive, so exported power appears as negative. To convert values from one system to the other, invert the signs of both active and reactive power. On the P-Q capability diagram this mirrors the plot through the origin. IEC, IEEE and IEEE 1547-2018 use the generator convention. The VDE application guide uses the consumer convention. Meters and plant controllers may use their own conventions. Some let you configure the power sign, and power factor sign modes vary, so check the documentation before you enter reactive power or power factor setpoints.
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explainsc1 drafted · lead Reactive power
Defines whether positive reactive power means over-excited injection (raising voltage) or under-excited absorption (lowering voltage).
sec=3.2 h=7db7c94e4415sec=3.2 h=a37a1edffb15sec=h30 h=c47e00cd11afrelated_toc2 drafted · lead Active power
In the generator convention, active power output is positive and active power drawn from the grid is negative.
sec=3.2 h=7db7c94e4415sec=3.2 h=a37a1edffb15c3 drafted · lead P-Q capability diagram
To convert between the consumer and generator conventions, invert the signs of P and Q. On the P/Q diagram this mirrors the plot through the origin.
sec=3.2 h=7db7c94e4415sec=3.2 h=a37a1edffb15c4 verified · fact Power factor
Meters and controllers sign power factor in different ways, for example by following real power, by following reactive power, or by quadrant.
tbl=41 h=1b5c81f51ef9tbl=5.r9 h=3b8f180e8b73sec=2.3.10 h=42a5bb2bf830verified by: review-workflowverified on: 2026-10-24
c5 verified · fact IEEE 1547-2018 proposed
This standard states its requirements in generator sign convention, which is the opposite of load sign convention.
sec=h30 h=c47e00cd11afverified by: review-workflowverified on: 2026-10-24
The units say IEC uses the generator reference-arrow system internationally.
sec=3.2 h=7db7c94e4415sec=3.2 h=a37a1edffb15The units say IEEE uses the generator reference-arrow system internationally.
sec=3.2 h=7db7c94e4415sec=3.2 h=a37a1edffb15The VDE application guide uses the consumer reference-arrow system.
sec=3.2 h=7db7c94e4415sec=3.2 h=a37a1edffb15verified by: review-workflowverified on: 2026-10-24
c9 drafted · lead SEL-735 Power Quality and Revenue Meter proposed
This meter reports VARs in four quadrants, following the IEEE VAR sign convention.
sec=h280 h=cd8283e51585c10 drafted · lead Tesla Site Controller proposed
This controller assumes a defined meter sign convention when it measures and sets control points.
sec=4.3.1 h=af0c396e2556related_to c4