Tempco TEC-9100, Инструкция по эксплуатации

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8
PV Shift
In certain applications it is desirable to shift the controller
display value (PV) from its actual value. This can easily
be accomplished by using the PV shift function.
The SHIF function will alter PV only.
Example: A process is equipped with a heater, a sensor,
and a subject to be warmed up. Due to the design and
position of the components in the system, the sensor
could not be placed any closer to the part. Thermal
gradient (differing temperatures) is common and
necessary to an extent in any thermal system for heat to
be transferred from one point to another. If the difference
between the sensor and the subject is 35°C, and the
desired temperature at the subject to be heated is 200°C,
the temperature at the sensor should be 235°C. You
should enter -35°C to subtract 35°C from the actual
process display. This in turn will cause the controller to
energize the load and bring the process display up to the
set point value.
Figure 3.7 PV Shift Application
3–9 Digital Filter
In certain applications, the process value is too unstable
to be read due possibly to electrical noise. A
programmable low-pass filter incorporated in the
controller is used to improve this. It is a first-order filter
with the time constant specified by the FILT parameter.
The default value of FILT is set at 0.5 seconds before
shipping. Adjust FILT to change the time constant from
0 to 60 seconds. 0 seconds means no filter is applied to
the input signal. The filter is characterized by the
following diagram:
Note
The filter is available only for PV, and is performed for
the displayed value only. The controller is designed to
use unfiltered signal for control even if the filter is
applied. A lagged (filtered) signal, if used for control,
may produce an unstable process.
The controller will enter failure mode if one
of the following conditions occurs:
1.
SBER occurs due to input sensor break
or input current below 1mA if 4–20 mA
is selected or input voltage below 0.25V
if 1–5V is selected.
2. ADER occurs due to the A-D converter
of the controller failing.
Output 1 and output 2 will perform the
failure transfer function as the controller
enters failure mode.
Output 1 failure transfer , if activated, will
perform:
1. If output 1 is configured as proportional
control (PB≠ 0), and BPLS is selected
for O1FT, then output 1 will perform
bumpless transfer. Thereafter, the
previous averaging value of MV1 will
be used for controlling output 1.
2. If output 1 is configured as proportional
control (PB≠ 0), and a value of 0 to
100.0% is set for O1FT, then output 1
will perform failure transfer. Thereafter,
the value of O1FT will be used for
controlling output 1.
3. If output 1 is configured as ON-OFF
control (PB=0), then output 1 will be
driven OFF if OFF is set for O1FT and
will be driven ON if ON is set for O1FT.
Output 2 failure transfer , if activated, will
perform:
1. If OUT2 is configured as COOL, and
BPLS is selected for O1FT, then output
2 will perform bumpless transfer.
Thereafter, the previous averaging value
of MV2 will be used for controlling
output 2.
2. If OUT2 is configured as COOL, and a
value of 0 to 100.0% is set for O2FT,
then output 2 will perform failure
transfer. Thereafter, the value of O1FT
will be used for controlling output 2.
3. If OUT2 is configured as alarm
function, and O2FT is set to OFF, then
output 2 will go off. Otherwise, output
2 will go on if O2FT is set to ON.
Alarm failure transfer is activated as the
controller enters failure mode. Thereafter,
the alarm will transfer to the ON or OFF
state preset by ALFT.
3–10 Failure Transfer
Figure 3.8 Filter Characteristics