ABB RELION REX640, Техническое руководство, Страница: 532 / 1960

Figure 306: Definition of the relay characteristic angle
The phase angle difference is calculated based on the Characteristic angle setting
(also known as Relay Characteristic Angle (RCA) or Relay Base Angle or Maximum
Torque Angle (MTA)). The Characteristic angle setting is done based on the method
of earthing employed in the network. For example, in case of an unearthed network,
the Characteristic angle setting is set to -90°, and in case of a compensated
network, the Characteristic angle setting is set to 0°. In general, Characteristic
angle is selected so that it is close to the expected fault angle value, which results
in maximum sensitivity. Characteristic angle can be set anywhere between -179°
to +180°. Thus, the effective phase angle (
ϕ
) for calculating the residual power
considering characteristic angle is according to the equation.
φ
= ∠ − − ∠ −
( )
( )
Uo Io Characteristic angle
(Equation 75)
In addition, the characteristic angle can be changed via the control signal
RCA_CTL
.
The
RCA_CTL
input is used in the compensated networks where the compensation
coil sometimes is temporarily disconnected. When the coil is disconnected, the
compensated network becomes isolated and the
Characteristic angle setting must
be changed. This can be done automatically with the
RCA_CTL
input, which results
in the addition of -90° in the Characteristic angle setting.
The value (ANGLE_RCA) is available in the monitored data view.
Protection functions 1MRS759142 F
532 REX640
Technical Manual