Line to neutral voltages available
Power is calculated from line to neutral voltages and phase currents. In case line to line voltages are
connected the line to neutral voltages can be calculated based on measured zero sequence voltage. In
line to neutral mode and in line to line voltage measurement mode when U0 is connected and
measured the following equations apply for power calculation:
Below is presented formula for three phase apparent power (S) calculation:
Below is presented formula for three phase active power (P) calculation:
Where phi is the angle difference between voltage and current.
Below is presented formula for three phase reactive power (Q) calculation:
Active power direction can be to forward or reverse direction. Active power direction can be indicated
simply by using Cos (φ). Cosine phi is calculated according the following formula:
Direction of reactive power is divided in to four quadrants. Reactive power may be inductive or
capacitive on both forward and reverse direction. Reactive power quadrant can be indicated simply by
using Tan (φ) together with Cos(φ). Tangent phi is calculated according the following formula:
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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