ABB RELION REX640 Technical Manual page 507

1MRS759142 C
REX640
Technical Manual
sector. The Correction angle setting should be done carefully as the phase angle error
of the measurement transformer varies with the connected burden as well as with the
magnitude of the actual primary current that is being measured. An example of how
Correction angle alters the operating region is as shown:
Zero torque line
Correction angle
operate current
Backward
GUID-339C78E1-81B7-41BD-929A-087A45A04935 V1 EN
Figure 275: Definition of correction angle
The polarity of the polarizing quantity can be changed (rotated by
180°) by setting Pol reversal to "True" or by switching the polarity of
the residual voltage measurement wires.
Residual power calculation
The Residual power calculation module calculates the magnitude of residual power
3UoIoCosφ. Angle φ is the angle between the operating quantity and polarizing
quantity, compensated with a characteristic angle. The angle value is received from
the Directional calculation module. The Directional calculation module enables the
residual power calculation only if the minimum signal levels for both operating
quantity and polarizing quantity are exceeded. However, if the angle calculation is not
valid, the calculated residual power is zero. Residual power (RES_POWER) is
calculated continuously and it is available in the monitored data view. The power is
given in relation to nominal power calculated as Pn = Un × In, where Un and In are
obtained from the entered voltage transformer and current transformer ratios entered.
Level detector
Level detector compares the magnitudes of the measured operating quantity (residual
current Io), polarizing quantity (residual voltage Uo) and calculated residual power to
Maximum torque line
forward direction (RCA = 0˚)
-Uo (Polarizing quantity)
Io (Operating quantity)
Forward
area
Minimum
Backward
area
Section 4
Protection functions
Forward
area
Correction angle
area
501