ZES ZIMMER LMG450, User Manual

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Z E S ZIMMER Electronic Systems GmbH Chapter 12
241
12 Miscellaneous
12.1 Frequently asked questions
12.1.1 Accuracy of measured and computed values
The accuracy of the directly measured values I, U and P can be found in the tables in 13.3.3
‘Accuracy’. The following calculations illustrate how to use these tables and how to calculate
the error for other values (l).
The read value of device should be:
U
trms
=230.000V, range 250V, peak range 400V
I
trms
=0.95000A, range 1.2A, peak range 3.75A
λ
=0.25000
f=50.0000Hz
P=54.625W, range 300W, peak range 1500W
AC coupling mode for the signal
From the table for the general accuracies, the following errors for voltage and current can be
determined (using the peak values of the respective measuring range):
V = V) + V ( = Rng.) of % Rdg.+ of % ( = U 315 . 0 02 . 0 115 . 0 05 . 0 05 . 0
± ± ± ∆
mA = mA) + mA ( = Rng.) of % Rdg.+ of % ( = I 35 . 2 875 . 1 475 . 0 05 . 0 05 . 0
± ± ± ∆
W = mW) + mW ( = Rng.) of % Rdg.+ of % ( = P 638 . 0 600 24 . 38 04 . 0 07 . 0
± ± ± ∆
The power factor is computed as follows:
λ
=
P
S
=
P
U * I
The absolute maximum error for power factor is calculated corresponding to the rules of error
computation using the total differential:
∆ ∆ ∆ ∆ λ ∂λ
∂
∂λ
∂
∂λ
∂
=
P
* P +
U
* U +
I
* I
∆
∆ ∆ ∆
λ
=
P
U * I
-
P* U
I *U
-
P* I
I * U
2 2