Proportional Integral (Pi) Control Loops - Daikin MicroTech Operation And Maintenance

Table 14: Setpoint Calculation Examples
Example A – Stand-Alone Unit, No remote sensor, No network communication
Given
Occupancy Mode = Occupied and Unit Mode = Heat
Space Temp Setpoint = (not used)
Setpoint Offset = (from LUI) = 0.0°F
Setpoint Shift = (not used) = 0.0°F
OHS = 69.8°F
Effective setpoint calculations
Effective Setpoint = OHS + AbsOffset + Setpoint Offset + Setpoint Shift
= 69.8°F + 0.0°F + 0.0°F + 0.0°F = 69.8°F
Example B – Stand-Alone Unit, Remote sensor with 55ºF – 95ºF Setpoint, No network communication
Given
Occupancy Mode = Occupied and Unit Mode = Heat
Space Temp Setpoint = 71.0°F (from remote sensor)
Setpoint Offset = -1.0°F (from LUI)
Setpoint Shift = (not used) = 0.0°F
OCS = 75.0°F, OHS = 70.0°F
Effective setpoint calculations
Absolute Offset = Setpoint - (OCS + OHS) / 2 = 71°F - (75.0°F + 70.0°F) / 2 = -1.5°F
Effective Setpoint = OHS + AbsOffset + Setpoint Offset + Setpoint Shift = 70.0°F - 1.5°F - 1.0°F - 0.0°F = 67.5°F
Example C – Stand-Alone Unit, Remote sensor with +/- 5°F, BACnet network communication
Given
Occupancy Mode = Occupied and Unit Mode = Heat
Space Temp Setpoint = 71.0°F (from network input)
Setpoint Offset = +3.0°F (from remote sensor)
Setpoint Shift = (from network input) = -2.0°F
OCS = 74.0°F, OHS = 68.0°F
Effective setpoint calculations
AbsOffset = Setpoint - (OCS + OHS) / 2 = 71.0°F - (72.0°F + 68.0°F) / 2 = 1.0°F
Effective Setpoint = OHS + AbsOffset + Setpoint Offset + Setpoint Shift = 68.0°F + 1.0°F + 3.0°F – 2.0°F = 70.0°F

Proportional Integral (PI) Control Loops

The MicroTech UVC uses PI-loop control for heating, cooling
and ventilation processes within the unit ventilator. Numerous
PI algorithms can be used depending upon the unit ventilator
configuration (Table 15).
Table 15: PI Loop List
PI loops
PI-1 Single Zone VAV Fan
PI-2 Economizer / Free Cooling
PI-3 Modulating Cooling Valve
PI-4 Modulating Hot Water Valve
PI-5 Face and Bypass Damper
CO / Demand Control
2
PI-6
Ventilation
PI-7 DAT Low Limit
PI-8 Electric Heat
OM 1280-2 • MICROTECH UNIT CONTROLLER
Setpoint
Effective Heating or Cooling Temperature Setpoint
Effective Discharge Air Temperature Setpoint
Effective Discharge Air Temperature Setpoint
Effective Discharge Air Temperature Setpoint
Effective Discharge Air Temperature Setpoint
Effective Space CO Setpoint
2
Effective Reheat Discharge Air Temperature
Setpoint
Effective Discharge Air Temperature Setpoint
Feedback
(controlled variable)
Control Temperature
Discharge Air Temperature
Discharge Air Temperature
Discharge Air Temperature
Discharge Air Temperature
Space CO
2
Discharge Air Temperature
Discharge Air Temperature
32
Description of Operation
Output
Fan Speed
Position the OA Damper
Modulating Cooling Valve Position
Modulating Hot Water Valve Position
Face and Bypass Damper Position
Position the OA Damper
Position the OA Damper
Electric Heat Stage
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