GE L90 Instruction Manual page 357

5 SETTINGS
By making the characteristic angle adjustable and providing for both negative and positive values of the minimum operating
power a variety of operating characteristics can be achieved as presented in the figure below. For example, section (a) in
the figure below shows settings for reverse power, while section (b) shows settings for low forward power applications.
(a)
OPERATE
(c)
RESTRAIN
(e)
842702A1.CDR
Figure 5–122: DIRECTIONAL POWER ELEMENT SAMPLE APPLICATIONS
• DIR POWER 1 RCA: Specifies the relay characteristic angle (RCA) for the sensitive directional power function. Appli-
cation of this setting is threefold:
1. It allows the element to respond to active or reactive power in any direction (active overpower/underpower, etc.).
2. Together with a precise calibration angle, it allows compensation for any CT and VT angular errors to permit more
sensitive settings.
3. It allows for required direction in situations when the voltage signal is taken from behind a delta-wye connected
power transformer and the phase angle compensation is required.
For example, the active overpower characteristic is achieved by setting
setting
DIR POWER 1 RCA
setting
DIR POWER 1 RCA
• DIR POWER 1 CALIBRATION: This setting allows the relay characteristic angle to change in steps of 0.05°. This may
be useful when a small difference in VT and CT angular errors is to be compensated to permit more sensitive settings.
GE Multilin
Q
RESTRAIN
P
o
RCA = 180
SMIN > 0
Q
OPERATE
P
o
RCA = 0
SMIN < 0
Q
OPERATE
RESTRAIN
P
o
RCA = 90
SMIN > 0
to "90°", active underpower by setting
to "270°".
L90 Line Current Differential System
5.6 GROUPED ELEMENTS
(b)
Q
RESTRAIN
OPERATE
P
o
RCA = 180
SMIN < 0
(d)
Q
OPERATE
P
RESTRAIN
o
RCA = 0
SMIN > 0
(f)
Q
RESTRAIN
OPERATE
P
o
RCA = 270
SMIN < 0
to "0°", reactive overpower by
DIR POWER 1 RCA
to "180°", and reactive underpower by
DIR POWER 1 RCA
5
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