TE Technology TC-720 - Manual (Page 37)

Multi-Speed Fan Control: Alarm 1 can be used for regulating a speed-controlled fan. It can be used to control a
separate speed-control input wire/terminal, or to control the input power directly if the peak current draw is 2 A
or less. To adapt between two-wire and three-wire control schemes the polarity of this control can be reversed to
increase or decrease duty cycle as a function of the main power output %.
The fan control is useful for controlling the hot-side fan of a TE cooler. One example is having the fan off when the
cooler is off or in heating mode, or run at a low speed when the output is at a low level. The speed can be
programmed to increase as the main output% increases. Various PWM frequencies are available for the fan which
allows the control of many different models of fans.
The fan speed control incorporates an initial period of operation at 100% duty cycle when the output is first turned
on, before decreasing to the fan output level as determined by settings. This fan delay is user variable, and helps
ensure the fan has been given full voltage to start the fan blades spinning, before power is decreased. It is useful
because fan bearings age, potentially requiring increased start-up voltages.
Speed control should only be used on fans designed to have a controllable speed. Standard two-wire fans
not designed for speed control may fail if operated with speed control, creating a hazardous condition. Fans
supplied on TE Technology, Inc. products are NOT designed for speed control unless specifically stated.
2.4.12 TEMP 1 OFFSET
Values: -10.0 °C to +10.0 °C
Default value = 0.0 °C
Description: Offsets the control sensor value for both the display and control algorithm.
2.4.13 TEMP 2 OFFSET
Values: -10.0 °C to +10.0 °C
Default value = 0.0 °C
Description: Offsets the secondary sensor value for both the display and control algorithm.
2.4.14 CONTROL RANGE
Values: -40 to +199, applies to both HIGH and LOW settings
Default value for HIGH = 070
Default value for LOW = -20
Description: Sets the maximum and minimum temperatures available in the SET TEMPERATURE menu. This is a
safety feature that helps to limit the set point to the safe operating temperature of the system being controlled.
Adjustments are in 1 °C increments, and the high setting must be higher than the low setting.
Note: If the CONTROL RANGE is adjusted such that it is no longer inclusive of the SET TEMPERATURE, the
controller will continue to control to that SET TEMPERATURE. However, once you scroll to the SET TEMPERATURE
menu, the SET TEMPERATURE will automatically reset to be within the CONTROL RANGE, and the output power
will adjust accordingly. The SET TEMPERATURE can then only be set within the CONTROL RANGE.
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