ABB REL 301, Instruction Manual

Page: 33 / 132

I.L. 40-386.3
2-12 (10/94)
unless 21BI operates. This prevents operation of the distance relay on load. The OSB
signal is also applied to the reclosing logic for initiating RB.
The following quantities are used for the blinder sensing:
VXG = Phase to ground voltage, VAG or VBG
I
X
= Phase current in
φ
A or
φ
B
R
C
= Setting of the unit OS inner for 21BI (R
T
) or OS outer for 21BO (R
U
). RT for inner
blinder (21BI), RU for outer blinder (21BO).
PANG = The positive sequence line impedance angle. Setting of (Ang Pos.).
Operation occurs if the operating voltage leads the polarizing voltage. The character-
istics are as shown in
Figure 2-18b.
Blinder reaches are determined by the setting of OS inner and OS outer, respectively.
2.4.16.1 Subsequent Out-of-Step Security Logic
Model power system tests, when using a motor-generator-set, show that the Zone1 im-
pedance unit may overreach or respond to a reversed fault. This was attributable to
motor-generator set instability following delayed clearing on an external fault. The
Zone1 relay, in all cases, identified the fault location and type correctly and responded
much later to the swing condition.
Logic was added utilizing the inner blinder and Zone1 sensing sequence, plus a 50 ms
timing action
(as shown in Figure 2-18a) , AND-131A, AND-131B, AND-131C and OR-
122A, to differentiate between a fault and a subsequent out-of-step condition. This
logic will not affect normal Zone1 trip time, nor will it affect normal out-of-step block-
ing.
2.4.17 Oscillographic Data
The oscillographic data has 8 samples per cycle, 1 cycle pre-trigger and 7 cycles post-
trigger. It includes 16 events and 24 digital intermediate targets (test points). The data
can be accessed via the communication port.
The oscillographic data is controlled by one of the following selections in the OSC Data
function:
Trip (TRIP) — data taken only if trip action occurs
Zone2 (Z2TR) — data taken if Zone2 units pick up or any trip action occurs.
Blinder
Line Polarizing Operating
Left -j(VXG + IXRC (PANG–90
°
) IX (PANG–90
°
)
Right j(VXG - IXRC (PANG–90
°
) IX (PANG–90
°
)