Meatest 9010+, User Manual

Page: 70 / 79

This example is based on following parameters:
- Function: AC active power
- Set value: 500 W (100 V, 10 A, 60° phase shift), 50 Hz
Individual items in formula are then calculated like this:
- dU = 0.025 % + 0.010 % of range = 0.045 % of 100 V value
- dI = 0.05 % + 0.01 % of range = 0.06 % of 10 A value
- dPF = [1 – cos (60 + 0.15) / cos 60] ∙ 100 = 0.45 %
AC power uncertainty is then calculated as dP =

(0.045
2
+ 0.06
2
+ 0.45
2
+ 0.03
2
) = 0.46 %
Range: -1.0000 – +1.0000
Uncertainty is determined by formula , where:
-

is set phase shift between voltage and current
- d

is uncertainty of set phase shift
Electric energy uncertainties are determined by the same formulas as power with addition of time period
uncertainty of 0.01 % + 0.3 s. Final formulas are therefore:
- for DC
- for AC
where dt is calculated as 0.01 + 30/set period.
This example is based on following parameters:
- Function: AC energy
- Set power: 460 W (230 V, 2 A, 0° phase shift), 50 Hz
- Set period: 5 minutes
Individual items in formula are then calculated like this:
- dU = 0.03 % + 12 mV = 0.035 % of 230 V value
-
dI = 0.07 % + 200 µA = 0.08 % of 2 A value
- dPF = [1 – cos (0 + 0.15) / cos 0] ∙ 100 = 0.0003 %
- dt = 0.01 % + 0.3 s = 0.11 % of 5 minute period
AC energy uncertainty is then calculated as dE =

(0.035
2
+ 0.08
2
+ 0.0003
2
+ 0.11
2
+ 0.03
2
) = 0.14 %
dPF = abs [cos (φ + dφ) / cos (φ)] + 0.0005
dE =

(dU
2
+ dI
2
+ dt
2
+ 0.01
2
)
dE =

(dU
2
+ dI
2
+ dPF
2
+ dt
2
+ 0.03
2
)