Tempco PCM10005, Инструкция по эксплуатации

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3–8 PV Shift
In certain applications it is desirable to shift the con-
troller 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 sen-
sor, 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 com-
mon and necessary to an extent in any thermal sys-
tem 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.
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 dia-
gram:
Note
The filter is available only for PV, and is performed for the dis-
played 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 fail-
ure 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 previ-
ous 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 con-
trolling 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. There-
after, 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 trans-
fer. 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 3.7 PV Shift Application
Figure 3.8 Filter Characteristics