ABB 615 Series ANSI, Техническое руководство

Страница: 588 / 713

1MAC050144-MB C
Section 8
Measurement functions
615 series ANSI 581
Technical Manual
exceeds Voltage dip set 1 is not detected (and recorded) immediately but only if no longer
dip indication for the same dip variation takes place and the maximum duration time for
dip variation is not exceeded before the signal magnitude rises above Voltage dip set 3.
There is a small hysteresis for all these limits to avoid the oscillation of the output
activation. No drop-off approach is applied here due to this hysteresis.
Consequently, only one event detection and recording of the same variation type can take
place for one voltage variation, so the longest indicated variation of each variation type is
detected. Furthermore, it is possible that another instantaneous dip event replaces the one
already indicated if the magnitude again undershoots Voltage dip set 1 for the set time after
the first detection and the signal magnitude 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.
The user should enter the settings for "VVa x time 1" "VVa x time 2" "VVa x time 3" in
the correct order to as to satisfy the relationship mentioned above as the relay will work as
per the parameters set by the user..
8.12.4.5 Three/single-phase selection variation examples
The provided rules always apply for single-phase (Phase Mode is "Single Phase") power
systems. However, for three-phase power systems (where Phase Mode is "Three Phase"),
it is required that all the phases have to be activated before the activation of the PICKUP
output. Interruption event indication requires all three phases to undershoot Voltage Int set
simultaneously, as shown in Figure 310. When the requirement for interruption for "Three
Phase" is no longer fulfilled, variation is indicated as a dip as long as all phases are active.
In case of a single-phase interruption of Figure 311, when there is a dip indicated in
another phase but the third phase is not active, there is no variation indication pickup when