26 COI/TZIDC/TZIDC-200-EN |
TZIDC, TZIDC-200
3.11.7
TOL_BAND – Tolerance band
The "tolerance band"
TOL_BAND
de
fi
nes a ± range around
the position setpoint. When the position of the valves and
fi
ttings reaches this range, the parameter set of the positioner
is toggled to a di
ff
erent algorithm that is used to continue with
a slow controlling actio n until the dead band
DEADBAND
is
reached.
The system is only considered balanced once the sensitivity
range is reached (see parameter
ADJ_MODE
on page 12.)
Input value
in steps of 0.1 %
3.11.8
DEADBAND – Dead band
The "dead band"
DEADBAND
de
fi
nes a ± range around the
position setpoint. Once the valv es and
fi
ttings 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 steps of 0.01 %
3.11.9
DB_APPR – Dead band approach
The
DB_APPR
parameter speci
fi
es 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 e
ff
ects 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
ENTER
until the countdown from 3 to 0 is
fi
nished. The test is activated . The display shows the control
loop symbol and a
fl
ashing message.
The test is automatically sto pped after two minutes and can
also be stopped by pressing any button.
NOTE
It is not possible to activate the test when the safe position is
active (see parameter
FAIL_POS
on page 31). Instead, the
message
FAIL_POS
is displayed.
3.11.10
DB_CALC – Dead-band determination
In standard automatic adjustme nt, the algorithm determines
the dead band as well as th e end positions and control
parameters. In some applications, you may need to perform a
new automatic adjustment after in stallation in the system, but
to leave the dead band at a preset value.
DB_CALC
o
ff
ers the following setting options:
— ON (automatic adjustment with dead band determination)
— OFF (automatic adjustment without dead band
determination)
conf
mA
%
C
°
conf
mA
%
C
°
conf
mA
%
C
°
conf
mA
%
C
°
