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5–5 Heat-Cool Control
An injection mold is required to be controlled at
120°C to ensure a consistent quality for the parts. An oil
pipe is buried in the mold. Since plastics are injected at
a higher temperature (e.g., 250°C), the circulation oil
needs to be cooled as its temperature rises. Here is an
example at right:
PID heat-cool is used for the example at right.
To achieve this, set the
following parameters in the setup menu:
Adjust SP1 to 120.0°C, CPB to 125(%) and
DB to -4.0(%).
Apply auto-tuning at 120°C for a new system
to get optimal PID values. See section 3-19.
Adjustment of CPB is related to the cooling
medium used. If water is used as the cooling
medium instead of oil, the CPB should be set at
250(%). If air is used as the cooling medium
instead of oil, the CPB should be set at 100(%).
Adjustment of DB is dependent on the system
requirements. A more positive value of DB will
prevent unwanted cooling action, but will
increase the temperature overshoot, while a
more negative value of DB will achieve less
temperature overshoot, but will increase
unwanted cooling action.
FUNC = BASC
IN1 = PT.DN
IN1U = °C
DP1 = 1-DP
OUT1 = REVR
O1TY = RELY
CYC1 = 18.0 (seconds)
O1FT = BPLS
OUT2 = COOL
O2TY = 4–20
O2FT = BPLS
SELF = STAR
5–4 Cool Only Control
A TEC-9300 is used to control a refrigerator with
the temperature below 0°C. To avoid set point
adjustment beyond the desired range, SP1L is set at
-10°C and SP1H is set at 0°C. Because the temper-
ature is lower than the ambient, a cooling action is
required, so select DIRT for OUT1. Since output 1
is used to drive a magnetic contactor, select RELY
for O1TY. Because a small temperature oscillation
is tolerable, use ON-OFF control to reduce the over-
all cost. To achieve ON-OFF control, PB1 is set to
zero and O1HY is set at 0.1°C.
Key menu
FUNC
IN1
IN1U
DP1
OUT1
O1TY
CYC1
O1FT
OUT2
O2TY
O2FT
SELF
SP1
CPB
DB
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