ABB 615 series Technical Manual page 666

Section 4
Protection functions
660
PICKUP output to activate. Even if more than two voltages drop below Voltage pickup
value, PICKUP output is not activated.
When the Voltage selection setting is "Positive Seq", the positive-sequence component is
compared with the set Voltage pickup value. If it is lower than the set Voltage pickup
value, the PICKUP output is activated.
Once PICKUP is activated, the function monitors the behavior of the voltage defined by
Voltage selection setting with the defined LVRT curve. When defined voltage enters the
operating area, the TRIP output is activated instantaneously. The pulse length of TRIP is
fixed to 100 ms. PICKUP also deactivates along with TRIP.
If a drop-off situation occurs, that is, voltage restores above Voltage pickup value, before
TRIP is activated, the function does not reset until maximum recovery time under
consideration has elapsed, that is, PICKUP output remains active.
LVRT curve is defined using time-voltage settings coordinates. The settings available are
Recovery time 1...Recovery time 10 and Voltage level 1...Voltage level 10. The number
of coordinates required to define a LVRT curve is set by Active coordinate settings.
When Recovery time 1 is set to non-zero value, it results into horizontal
characteristics from point of fault till Recovery time 1.
Two examples of LVRT curve are defined in
corresponding settings in
It is necessary to set the coordinate points correctly in order to avoid
maloperation. For example, setting for Recovery time 2 should be greater
than Recovery time 1. Recovery time 1...Recovery time 10 are the
respective time setting from the point of fault.
Figure 329
Table 565.
1MAC059074-MB A
and Figure 330 with
615 series ANSI
Technical Manual