METREL MI 2893 - Voltage Events

MI 2893 / MI 2892 / MI 2885 Measurement methods
195
 
%
1
2
,
Nom
n
i
iOver
Nom
O ver
U
n
U
U
U




(72)
Under-deviation and over-deviation parameters may be useful when it is important to avoid, for
example, having sustained under-voltages being cancelled in data by sustained over-voltages.
Note: Under-deviation and Over-deviation parameters are always positive values.
5.1.13 Voltage events
Measurement method
Standard compliance: IEC 61000-4-30 Class A (Section 5.4)
The basic measurement for event is U
Rms(1/2)
. U
Rms(1/2)
is value of the RMS voltage measured over 1 cycle,
commencing at a fundamental zero crossing and refreshed each half-cycle.
The cycle duration for U
Rms(1/2)
depends on the frequency, which is determined by the last 10/12-cycle
frequency measurement. The U
Rms(1/2)
value includes, by definition, harmonics, interharmonics, mains
signalling voltage, etc.
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
-375
-250
-125
0
125
250
375
Dip Duration
U
Rms(1/2)
1-cycle long
U (Voltage)
U
Rms(1/2)
Dip Threshold
Dip Hysteresis
Figure 159:U
Rms(1/2)
1-cycle measurement