Cooling Parameters Module (5-02) (Optional)
The cooling output (O2) is software selectable with dual alarm models (For the P48, this is referred to as the Second Control Output). This output operates as an independent cooling output for systems that use heating and cooling. To enter the Cooling Output Module, the cooling output of the controller must first be selected in Alarm Module (4-AL). When cooling is selected, alarm 2 is used for the cooling output.
The front panel indicator A2 illuminates when the cooling output (O2) is on. Cooling output power is defined as ranging from -100% (full cooling) to
0% (no cooling, unless a heat-cool band overlap is used). See Output Power
Limits in Module 2 for maximum and minimum settings. The same PID values control both heat and cool.
Cooling Output Cycle Time (CYC2)
A value of 0 turns off the cooling output, independent of cooling power demand.
CYC2 - 0 to 250 seconds
Cooling Relative Gain (GAn2)
This parameter defines the gain of the cooling band relative to the heating band. A value of 0.0 places the cooling output into ON/OFF Control mode with the ON/OFF Control Hysteresis (CHYS) in Output Parameter Module
(2-OP) becoming the cooling output hysteresis. This may be done independent of the main output control mode (PID or ON/OFF). Relative gain is generally set to balance the effects of cooling to that of heating for best control. Figures 19, 20, & 21, Heat/Cool Operation, illustrate the effect of different gains.
GAN2 - 0.0 to 10.0
Heat and Cool Overlap/Deadband (db-2)
This parameter defines the area in which both heating and cooling are active (negative value) or the deadband area between the bands (positive value). The parameter units are degrees or tenth’s of degrees (depending on system resolution). If a heat/cool overlap is specified, the displayed percent output power is the sum of the heat power (O1) and the cool power (O2).
db-2 - -999 to 9999
When the Cooling Relative Gain is set to zero for ON/OFF Control mode, this parameter should only be set to a positive value or zero. The Heat/Cool
Operation Figures illustrate the effects of different deadbands.
Figure 19, Heat/Cool Operation (db=0)
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Figure 20, Heat/Cool Operation (db>0)
When using the cooling output, observe the controlled temperature characteristics. If the temperature remains above setpoint with a sluggish return, increase the cooling gain. Similarly, if the temperature drops too
