-Uo (Polarizing quantity)
Backward
area
Forward
area
Io (Operating quantity)
Zero torque line
Minimum
operate current
Maximum torque line
forward direction (RCA = 0˚)
Correction angle
Correction angle
Forward
area
Backward
area
Figure 190: 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, and depend on the
Io signal Sel and Uo signal Sel settings.
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 the set
Current start value (×In), Voltage start value (×Un) and
Power start value (×Pn) respectively. When all three quantities exceed the limits,
Level detector enables the Timer module.
When calculating the setting values for Level detector, it must be considered that
the nominal values for current, voltage and power depend on whether the residual
quantities are measured from a dedicated measurement channel or calculated from
phase quantities, as defined in the
Io signal Sel and Uo signal Sel settings.
For residual current Io, if "Measured Io" is selected, the nominal values for primary
and secondary are obtained from the current transformer ratio entered for residual
Protection functions
1MRS758755 C
380
REC615 & RER615
Technical Manual
