ABB RELION REX640 Technical Manual page 1590

Section 9
Control functions
1584
movement into wrong direction, maximum number of tuning sequences exceeded or
simultaneous indication from both end switches of the coil. There is a dedicated
MOT_ALARM output indicating no detected coil movement after activating
RAISE_OWN or LOWER_OWN outputs.
After ALARM indication with ALARM_STS "Umin not reached" or "Cannot obtain
minimum Uo variation" the coil is moved to a position which is defined with Error
position setting. The same procedure is executed after CLC_SEQ_WRN indication.
The options are to move the coil to the position from where the tuning procedure was
started, leave it to its present position or to move the coil to the default position which
is settable by the user.
The active tuning range of the arc suppression coil can be limited with Minimum
current and Maximum current settings. Once the operating limits are activated, the
controller does not leave the selected range during the tuning procedure. If the
operating limits are applied, the limited range of the coil is indicated on the HMI
resonance curve view.
Operation during earth faults
The controller supports three modes for operation during earth fault. The active mode
can be selected with EF mode setting. The available modes are "Blocked during EF",
"Resonance" and "Tuning during EF".
• Blocked during EF: No coil movement when the earth fault is detected
• Resonance: Coil is moved to the resonance point which is determined during the
healthy-state operation of the network.
• Tuning during EF: The controller determines the network parameters during a
sustained earth fault and maintains the set compensation level. The controller can
also detect network switching operations and tune the ASC correspondingly (for
example, disconnecting feeders to isolate the earth fault). Tuning during EF can
be performed when the measured zero-sequence voltage is below 80 percent of
the system's nominal phase-to-earth voltage. If the measured zero-sequence
voltage is over 80 percent of the system's nominal phase-to-earth voltage, the
"Blocked during EF" mode is automatically switched into use.
Fixed parallel coil control
PASANCR supports the control of the fixed parallel coil. The ampere value and the
nominal voltage of the coil can be set with Fix coil value and Fix coil V Nom settings.
The treatment of the fixed parallel coil is selected with Fix coil type setting. By
applying "OFF" or "ON", the controller cannot automatically switch the connection
status of the fixed parallel coil. If "Automatic" is selected, the controller can change
the connection status of the fixed parallel coil to reach the desired compensation level.
During the automatic operation, the controller tunes the adjustable ASC first. If the
desired compensation level cannot be reached, the fixed parallel coil can be switched
on or off. The presence of the fixed parallel coil in the system has effect on correct
tuning when the compensation mode is relative.
Absolute detuning current can be calculated:
1MRS759142 C
REX640
Technical Manual