Sel 411L - Table 3.5 87 LP Phase Differential Elements Relay Word Bits; Table 3.6 87 LQ Negative-Sequence Differential Element Settings; Table 3.7 87 LQ Negative-Sequence Differential Element Analog Quantities

P.3.36
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
87L Differential Elements
extended security settings. You may therefore set the blocking angle setting in
the extended security mode, 87LPAS, conservatively, while setting the regular
security blocking angle setting, 87LPA, to be more sensitive.
87LQ Negative-Sequence Differential Element
This section describes the application without in-line transformers
(87XFMR = N). Refer to 87L Differential Applications With In-Line
Transformers if you apply the relay to a line including a power transformer
connected in series.
As Figure 3.22 shows, the negative-sequence differential element applies the
basic settings of the Alpha Plane characteristic (pickup, radius, and blocking
angle, see Table 3.6) to its negative-sequence operating quantities (magnitude
of the differential current, ratio, and angle of the Alpha Plane, see Table 3.7).
The logic, settings, operating quantities, and Relay Word bits are virtually
identical between the phase- and negative-sequence differential elements.
Refer to 87LP Phase Differential Elements for detailed explanation.
Table 3.5 87LP Phase Differential Elements Relay Word Bits
Name Description
87LP 87L phase differential element operated in any phase
87LA 87L phase differential element operated in A-phase
87LB 87L phase differential element operated in B-phase
87LC 87L phase differential element operated in C-phase
87L50A Overcurrent supervision of the phase differential element picked up in A-phase
87L50B Overcurrent supervision of the phase differential element picked up in B-phase
87L50C Overcurrent supervision of the phase differential element picked up in C-phase
Table 3.6 87LQ Negative-Sequence Differential Element Settings
Setting Description Range Default
87LQP Pickup threshold of the negative-sequence differ-
ential element in the normal security mode (pu)
OFF, 0.1–2 0.25
87LQR Radius of the negative-sequence differential ele-
ment in the normal security mode
1.2–8 6
87LQA Blocking angle of the negative-sequence differen-
tial element in the normal security mode (deg)
90–270 195
87LQPS
a
a
Advanced settings (EADVS = Y).
Pickup threshold of the negative-sequence differ-
ential element in the extended security mode (pu)
OFF, 0.1–2 0.3
87LQRS
a
Radius of the negative-sequence differential ele-
ment in the extended security mode
1.2–8 7.2
87LQAS
a
Blocking angle of the negative-sequence differen-
tial element in the extended security mode (deg)
90–270 234
Table 3.7 87LQ Negative-Sequence Differential Element Analog Quantities
Name Description Units
87IQFM Negative-sequence differential current (3I2) magnitude,
full-cycle cosine-filtered
pu
87KQ Alpha Plane ratio, negative-sequence –
87APQ Alpha Plane angle, negative-sequence Deg (±180°)