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136 HRB1684301-01
Chapter 16—Power, energy and power factor PowerLogic™ PM5500 series user manual
Energy delivered / energy received
The meter interprets energy delivered or received according to the direction of real
power (P) flow.
Energy delivered means positive real power flow (+P) and energy received means
negative real power flow (-P).
Power factor (PF)
Power factor (PF) is the ratio of real power (P) to apparent power (S), and is a number
between 0 and 1.
An ideal, purely resistive load has no reactive components, so its power factor is one
(PF = 1, or unity power factor). A purely inductive or capacitive load no resistive
components, so its power factor is zero (PF = 0).
True PF and displacement PF
The meter supports true power factor and displacement power factor values:
• True power factor includes harmonic content.
• Displacement power factor only considers the fundamental frequency.
PF lead / lag convention
The meter correlates leading power factor (PF lead) or lagging power factor (PF lag)
with whether the current waveform is leading or lagging the voltage waveform.
Current phase shift from voltage
For purely resistive loads the current waveform is in phase with the voltage waveform.
For capacitive loads, current leads voltage. For inductive loads, current lags voltage.
Quadrant Real (P) power flow Energy delivered or received
Quadrant 1 Positive (+) Energy delivered
Quadrant 2 Negative (-) Energy received
Quadrant 3 Negative (-) Energy received
Quadrant 4 Positive (+) Energy delivered
PF
P
S
---=
Current lead / lag and load type
Current and voltage in phase (resistive) Current leads voltage (capacitive) Current lags voltage (inductive)
270°
90°
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90°
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90°
270°
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