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Model
5C7-388 is capable of operating from an input supply voltage of 12
through 28 VDC, common to many available thermoelectric modules. The
self-contained MOSFET output devices deliver load currents from 0.1
to 25 amperes (NOTE: consult appropriate installation instructions
for power supply and heat sinking requirements for high current
operation). This unit will control total load power up to 680 watts
with a finite temperature resolution of 0.05°C.
The
output signal to the thermoelectric module is Pulse Width Modulated
and 2700 Hz operation. Pulse Width Modulation averages the amount of
energy provided to the module and reduces the extreme temperature
excursions that are experienced with an "on / off" system.
This tends to extend the life and reliability of the thermoelectric
devices. The PWM control scheme affords control accuracy to within
±0.05°C. at the control sensor.
The
controller tuning structure allows designation of a variety of
control features. The computer set value provides for manual control
of the output, either polarity, from 0% to 100% of load power.
Proportional bandwidth (P) in degrees, integral reset (I) in repeats
per minute, and the derivative rate (D) in minutes may be configured
for P, PI, PD, or PID control. In addition, a deadband control
(on/off) with an adjustable hysteresis may be selected. Differential
temperature control is offered when two input sensing thermocouple is chosen.
The
control temperature range of –328°F to 500°F
(-200°C to 260°C) is standard. The controllers’
primary set temperature is via the PC software. Additional set
temperature inputs include a remote set temperature potentiometer, a
0 to 3.3vdc signal, and a 4 to 20ma current loop. These secondary
inputs are used to define and "map" the secondary input to
an adjustable temperature range. Differential set temperature control
may also be selected from this configuration menu. All temperatures
may be consistently displayed in °C or °F.
Differential
control is accomplished by selecting the primary set temperature
with the second thermocouple input and establishing the offset with
the computer set temperature. The unit will control the differential
between Input 2 (reference temperature) and Input 1 (actual system temperature).
Two
types of control output modes may be selected. This determines the
direction of the current flow through the thermoelectric module
during the heat cycle. This current flow may be from Wire Point WP1
(+) to Wire Point WP2 (-). Alternatively, this current flow may be
reversed from WP2 (+) to WP1 (-) as selected in the configuration menu.
Several
alarm types may be selected which provide a 5 VDC output, rated for
25 ma of current. They consist of no alarm function, tracking alarm,
and fixed value alarm. Alarm set temperature values are entered in
the setup menu. The computer-controlled selection is available for
additional embedded controller input/output options. The alarm setup
menu also provides for selection of an alarm latching condition. The
alarm sensor may be either the control temperature sensor or a
secondary thermocouple sensor.
The
various alarms have the ability to determine the status of the
output power to the thermoelectric module or auxiliary heater. Power
may be maintained during an alarm condition or the main power may be
shut down
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