Omicron CMC 356 - Accuracy of Power Measurement

CMC 356 Reference Manual
84
6.11.6.5 Accuracy of Power Measurement
General
The power is calculated from one current channel and one voltage channel:
Active power: [W]
Apparent power: S = V
rms
x I
rms
[VA]
Reactive power: [var]
U
rms
= , I
rms
=
Accuracies
Conditions: integration time 1s, measurement signal sinusoidal, excitation
10-100 %, accuracy references the apparent power, error of the current
clamp is not taken into account.
Table 6-41:
Sampling rates
28.44kHz
9.48kHz
3.16kHz
Table 6-42:
Sampling rate
28.44kHz
P
1
T
---=*ut()*it() td
0
T

Q S
2
P
2
–= *sign_Q
1
T
--- * ut()
2
td
0
T

1
T
--- * it()
2
td
0
T

Frequency range Power Accuracy
1
AC Typical Guaranteed
10 Hz ... 100 Hz S ± 0.3 % ± 0.7 %
P±0.3% ±0.7%
Q±0.8% ±2%
Frequency range Power Accuracy
1
1
S = Apparent power
P = Active power
Q = Reactive power
AC Typical Guaranteed
10 Hz ... 2.2 kHz S + 0.3 % / - 1.2 % ± 2.5 %
P + 0.3 % / - 1,2 % ± 2.5 %
Q + 0.8 % / - 2.5 % ± 3.5 %
Actual - Expected
Full scale
x 100 %Relative error: