Amprobe DMII-PRO Data-Logger-Recorder - Manual (Page 28)

Page 28
DM-II™ Fuse Replacement/Voltage Selection Procedure
True RMS Voltage and Current (volts and amps): True RMS is calculated by using Parseval’s
theorem:
Real Power P (watts): The real power that performs the work of creating heat, light, motion, machine
output, etc.
Apparent Volt-Amperes S (VA): The total power required to be generated to provide the desired work-
ing power output.
Reactive Volt-Amperes Q (VAR): The “non-working” or “phantom” power that is needed to charge
capacitors and magnetize inductors, i.e. reactive power to sustain electromagnetic fields.
Vrms =
√Σ
V
2
n
n
P =
Σ
V
rmsn
I
rmsn
COS (
θ
DIFFn
)
n
Q =
Σ
V
rmsn
I
rmsn
sin (
θ
DIFFn
)
n
S = V
rms
I
rms
Irms =
√Σ
I
2
n
n