Tol_Band - Tolerance Band; Deadband - Dead Band; Db_Appr - Deadband Approach; Db_Calc - Deadband Determination - ABB TZIDC Manual

TZIDC, TZIDC-200 DIGITAL POSITIONER | COI/TZIDC/TZIDC-200-EN REV. B
TOL_BAND – Tolerance band
The "tolerance band" (TOL_BAND) defines a ± range around the
position setpoint. When the position of the valves and fittings
reaches this range, the parameter set of the positioner is
toggled to a different algorithm that is used to continue with a
slow controlling action until the dead band (DEADBAND) is
reached.
The line is only considered to be adjusted when it enters the
sensitivity range (see parameter ADJ_MODE page 15).
Input value in steps of 0.1 %
DEADBAND – Dead band
The DEADBAND defines a +/- range around the position set
point. Once the valves and fittings reach this range, the
positioner maintains this position.
Note
The dead band must always be 0.2% less than the tolerance
band.
Input value in increments of 0.01 %
DB_APPR – Deadband Approach
The parameter DB_APPR specifies the speed at which the dead
band is approached.
In rare cases, overshooting can occur when the valve position is
being compensated. This can be prevented by reducing the
speed of the dead-band approach.
TEST – Test
The test is used to activate the controller, and you can check the
effects of the changes to this parameter group, e.g., by
introducing setpoint changes or setpoint ramps using a current
source.
Normally, INACTIVE is shown in the display. To start the test,
press and hold the ENTER button, until the countdown displayed
on it has run from 3 to 0 and finished. The test is activated. The
display shows the control loop symbol and a flashing message.
The test is automatically stopped after two minutes and can also
be stopped by pressing any button.
Note
The test cannot be activated with an active safety position (see
parameter FAIL_POS page 37). Instead, the message FAIL_POS is
displayed.
DB_CALC – Deadband Determination
In standard automatic adjustment, the algorithm determines the
dead band as well as the end positions and control parameters.
In some applications, you may need to perform a new automatic
adjustment after installation in the system, but to leave the dead
band at a preset value.
DB_CALC offers the following setting options:
• ON (automatic adjustment with deadband determination)
• OFF (automatic adjustment without deadband
determination).
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