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Metering in reactive power (Q)
(ii)
Similar to the active power (P), the user should set the metering sign for the reactive power
(Q). The Q value will have the minus sign (–) based on the P value, when Lag is set for setting
[Current] (Figure 9.2-4.a). On the other hand, the Q value will have the plus sign (+) based on
the P value, when Lead set for the setting (Figure 9.2-4.b).
II
(Q>0)
III
(Q<0)
a. Q (shown in quadrant IV) has a minus sign
because the Q is supplied by the outside source.
The decision is made with the P (shown in the
quadrant IV, defined with [Power]=Send) having
"a plus sign" when the current lags the voltage.
[Current]=Lag
Figure 9.2-4 Sign of the reactive power (Q) ruled by setting [Current]
Polarity setting for power factor values
9.2.5
The power factor (PF) value is shown by the rule to align the plus/minus sign (±) of the P value
(i.e., setting [PF_sign]=AP, default setting). However, the user can change the rule (i.e., setting
[PF_sign]=AP+RP); as a result, the PF value will have the plus sign (+), provided both the P
value and the Q value have the same plus (+) sign or minus (–) sign.
AP setting
(i)
When the sign of the PF value is required to match with the sign of the P value, set AP for the
setting [PF_sign].
I
(Q>0)
V
IV
I
(Q<0)
b. Q (shown in quadrant IV) has a plus sign because
- 778 -
II
(Q<0)
III
I
(Q>0)
the Q is absorbed by the outside source. The
decision is based on the P (shown in the
quadrant I, defined with [Power]=Receive)
having "a minus sign" when the current leads
the voltage.
[Current]=Lead
6F2T0207 (0.01)
I
(Q<0)
V
IV
(Q>0)
GRE200 (5,6)
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