ABB RELION REX640 Technical Manual page 188

Section 3
Basic functions
182
current and positive- and negative-sequence current. The output IRES_CLC can be
connected to functions using the calculated residual current.
The current transducer selection can be made by setting Current input type to "Current
trafo" for conventional CT sensor or to "Current sensor" for current sensor type.
The sensor's or the CT's primary rated current can be set using Primary current setting.
The setting Secondary current defines the nominal current of the CT's secondary
winding. This is used as a reference to scale the measurements accordingly. These
settings also affect the scaling of the calculated residual current.
Current magnitude correction of an external CT can be made using settings Amplitude
Corr A, Amplitude Corr B and Amplitude Corr C.
Current angle correction of an external CT can be made using settings Angle Corr A,
Angle Corr B and Angle Corr C.
Rated secondary Val setting defines the ratio for sensor use. This value multiplied by
the Rated frequency setting (under Configuration/System) gives the sensor's
nominal voltage corresponding to the sensors' primary rated current.
Reverse polarity setting is used to reverse the polarity of phase CTs.
The WARNING output in the receiver is activated if the synchronization accuracy of
the sender or the receiver is worse than 4 μs. The output remains on for 10 seconds
after the synchronization accuracy returns within limits.
The ALARM in the receiver is activated if the synchronization accuracy of the sender
or the receiver is not within tolerances. The output is held on for 10 seconds after the
synchronization accuracy returns within limits. If the effect on protection is
negligible, the WARNING or ALARM output is not activated.
The SMV Max Delay setting defines how long the receiver waits for the SMV frames
before activating the ALARM output. This setting can be accessed via Configuration/
System. Waiting for the SMV frames delays the local measurements of the receiver
to keep them correctly time aligned. The SMV Max Delay values include sampling,
processing and network delay.
Frequency adaptive measurements for a three-phase current can be activated with the
setting Frequency adaptivity. Three selections are provided.
1MRS759142 C
REX640
Technical Manual