ABB RELION REX640, Техническое руководство, Страница: 1836 / 1960

or time requirement is again fulfilled. Another possibility is that if the time condition
is not fulfilled for an instantaneous dip detection but the signal rises above
Voltage
dip set 1, the already elapsed time is included in the momentary dip timer. Especially
the interruption time is included in the dip time. If the signal does not exceed
Voltage dip set 2 before the timer VVa dip time 2 has elapsed when the momentary
dip timer is also started after the magnitude undershooting
Voltage dip set 2, the
momentary dip event instead is detected. Consequently, the same dip occurrence
with a changing variation depth can result in several dip event indications but only
one detection. For example, if the magnitude has undershot
Voltage dip set 1 but
remained above
Voltage Intr set for a shorter time than the value of VVa dip time
1 but the signal rises between Voltage dip set 1 and Voltage dip set 2 so that the
total duration of the dip activation is longer than
VVa dip time 2 and the maximum
time is not overshot, this is detected as a momentary dip even though a short
instantaneous dip period has been included. In text, the terms "deeper" and "higher"
are used for referring to dip or interruption.
Although examples are given for dip events, the same rules can be applied to the
swell and interruption functionality too. For swell indication, "deeper" means that
the signal rises even more and "higher" means that the signal magnitude becomes
lower respectively.
The adjustable voltage thresholds adhere to the relationships:
VVa dip time 1 ≤ VVa dip time 2 ≤ VVa dip time 3.
VVa swell time 1 ≤ VVa swell time 2 ≤ VVa swell time 3.
VVa Int time 1 ≤ VVa Int time 2 ≤ VVa Int time 3.
There is a validation functionality built-in function that checks the relationship
adherence so that if
VVa x time 1 is set higher than VVa x time 2 or VVa x time
3, VVa x time 2 and VVa x time 3 are set equal to the new VVa x time 1. If VVa x time
2 is set higher than VVa x time 3, VVa x time 3 is set to the new VVa x time 2. If VVa
x time 2 is set lower than VVa x time 1, the entered VVa x time 2 is rejected. If VVa x
time 3 is set lower than VVa x time 2, the entered VVa x time 3 is rejected.
10.3.5.4 Duration measurement
The duration of each voltage phase corresponds to the period during which
the measured TRMS values remain above (swell) or below (dip, interruption) the
corresponding limit.
Besides the three limit settings for the variation types dip and swell, there is also
a specific duration setting for each limit setting. For interruption, there is only
one limit setting common for the three duration settings. The maximum duration
setting is common for all variation types.
The duration measurement module measures the voltage variation duration of each
phase voltage separately when the Phase mode setting is "Single Phase". The phase
variation durations are independent. However, when the Phase mode setting is
"Three Phase", voltage variation may start only when all the monitored phases
are active. An example of variation duration when Phase mode is "Single Phase"
can be seen in Figure 973 . The voltage variation in the example is detected as
an interruption for the phase B and a dip for the phase A, and also the variation
durations are interpreted as independent
U_B
and
U_A
durations. In case of single-
phase interruption, the
DIPST
output is active when either
ST_A
or
ST_B
is active.
The measured variation durations are the times measured between the activation
of the
ST_A
or
ST_B
outputs and deactivation of the
ST_A
or
ST_B
outputs. When
Power quality measurement functions 1MRS759142 F
1836 REX640
Technical Manual