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Description of Operation
Proportional Integral (PI) Control Loops
The MicroTech II UVC uses
Table 16: PI loop list
| PI loops | PI loop type | Set point | Feedback | Output | |
| (controlled | |||||
|
|
|
| variable) |
| |
| Space Temperature |
| Effective Heating or Cooling | Space Temperature | Calculated Discharge Air | |
| Temperature Setpoint | Temperature Setpoint Output | ||||
|
|
|
| |||
| Primary Cooling (Economizer) |
| Calculated Discharge Air Temperature | Discharge Air | Position the OA Damper | |
| Setpoint Output | Temperature | ||||
|
| Cascading |
| |||
| Secondary Cooling | Calculated Discharge Air Temperature | Discharge Air | Operate the Compressor | ||
| ||||||
| Setpoint Output | Temperature | ||||
|
|
|
| |||
| Primary Heating |
| Calculated Discharge Air Temperature | Discharge Air | Position the Wet Heat Valve or | |
| Setpoint Output | Temperature | F&BP Damper | |||
|
|
| ||||
|
|
|
|
|
| |
CO2 (optional) | Single | Effective CO2 Setpoint | Space CO2 | Position the OA Damper | ||
Low Limit | Single | Calculated Discharge Air Temperature | Discharge Air | Position the OA Damper | ||
Setpoint | Temperature | |||||
|
|
|
|
Figure 17: PI loop graphic for CO2
Effective | + - |
CO2 set point |
Space CO2
sensor
PI - 5
Position the OA damper
Discharge Air Temperature Control
The UVC uses two “cascading” PI loops to aid in providing very stable space temperature control. The Space Temperature
Figure 18: Cascading PI loop graphic 1 (primary heat)
Figure 19: Cascading PI loop graphic 2 (primary cool—economizer)
McQuay OM 751 | 29 |