American Standard UV05 Proportional Integral PI Control Loops, Discharge Air Temperature Control

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Description of Operation

Proportional Integral (PI) Control Loops

The MicroTech II 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. The UVC uses “single” and “cascading” PI loops where needed.

Table 16: PI loop list

		PI loops	PI loop type	Set point	Feedback	Output
		PI loops	PI loop type	Set point	(controlled	Output
					variable)
	PI-1	Space Temperature		Effective Heating or Cooling	Space Temperature	Calculated Discharge Air
	PI-1	Space Temperature		Temperature Setpoint	Space Temperature	Temperature Setpoint Output
				Temperature Setpoint		Temperature Setpoint Output
	PI-2	Primary Cooling (Economizer)		Calculated Discharge Air Temperature	Discharge Air	Position the OA Damper
	PI-2	Primary Cooling (Economizer)		Setpoint Output	Temperature	Position the OA Damper
			Cascading	Setpoint Output	Temperature
	PI-3	Secondary Cooling	Cascading	Calculated Discharge Air Temperature	Discharge Air	Operate the Compressor
				Calculated Discharge Air Temperature	Discharge Air
				Setpoint Output	Temperature
				Setpoint Output	Temperature
	PI-4	Primary Heating		Calculated Discharge Air Temperature	Discharge Air	Position the Wet Heat Valve or
	PI-4	Primary Heating		Setpoint Output	Temperature	F&BP Damper
				Setpoint Output	Temperature	F&BP Damper

	PI-5	CO2 (optional)	Single	Effective CO2 Setpoint	Space CO2	Position the OA Damper
	PI-6	Low Limit	Single	Calculated Discharge Air Temperature	Discharge Air	Position the OA Damper
	PI-6	Low Limit	Single	Setpoint	Temperature	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 PI-loop is used to calculate the Discharge Air Temperature Setpoint Output required to meet the Effective Temperature Setpoint Output. A second PI-loop (Primary Cooling, Secondary Cooling, or Primary Heating) is then activated to control the heating or cooling device required to achieve the calculated Discharge Air Temperature Setpoint Output.

Figure 18: Cascading PI loop graphic 1 (primary heat)

Figure 19: Cascading PI loop graphic 2 (primary cool—economizer)

McQuay OM 751

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Contents Date November DX Cooling Only Software Model UV05Group Applied Systems Introduction UVC Configuration ParametersGetting Started Description of OperationDescription Manual # Model-specific unit ventilator installation literatureAccessory-specific installation literature Software program literature Extreme temperature can damage system componentsDescription Acronym Abr Acronyms/AbbreviationsAcronyms and abbreviations OCS Display Format Using the Keypad/DisplayKeypad Functions Security LevelsON/STOP Key and LED Mode KeyFAN Key Arrow KeysViewing Actual Indoor Air Temperature IAT Using the Keypad/DisplayMenu Reference Changing Set PointsRW1 Abr Description DefaultChlo State Programming Description of OperationUVC Unit Modes Complete UVC-state diagramUVC state names and numbers OFF Mode StateNormal UVC modes State names DecimalFan Only Mode State a Night Purge Mode StateCant Heat State State D Emergency Heat Mode Super StateFull Heat State State Heat State State Auto ModeHeat Mode Super State Cant Heat State State B Cool Mode Super StateLow Limit State State E Econ State State Cool mode super state diagramMech State State Econ Mech State StateDischarge Air DA Heat State State Special Purpose Unit ModesLow Limit State State F Cant Cool State State CDepressurize Mode Pressurize ModePurge Mode Shutdown ModeSpecial purpose UVC unit mode priority Unit Mode PriorityNormal UVC mode priority Priority resultUnoccupied Mode Occupied ModeStandby Mode Occupancy mode priorityAdditional Occupancy Features Networked Space Temperature Sensor Capability Space Temperature Set PointsNetworked Set Point Capability Networked Set Point Offset CapabilityEffective Set Point Calculations Remote Wall-Mounted Sensor with +/-3F Adjustment optionalEffective set point calculations Set point calculation examplesExample a Example B Given Proportional Integral PI Control Loops Discharge Air Temperature ControlPI loop list PI loopsProportional Band PI Control ParametersOccupied, Standby, and Bypass Operation Indoor Air Fan OperationIntegral Time Outdoor Air Damper Operation OA temp sensor Space humidity Economizer enableEconomizer Networked Outdoor Humidity Sensor Capability Networked Space Humidity Sensor CapabilityCO2 Demand Controlled Ventilation optional Networked Space CO2 Sensor CapabilityAshrae Cycle Compressor OperationCompressor Envelope Compressor Cooling LockoutCompressor Start Delay Compressor Minimum On and Off TimersFloating-Point Actuator Auto-Zero, Overdrive and Sync Outdoor Air Fan OperationRemote Shutdown Input Signal Unoccupied Input SignalVentilation Lockout Input Signal External Binary InputsLights On/Off Signal Exhaust Interlock Input SignalFault Signal External Binary OutputsAuxiliary Heat Signal Exhaust Fan ON/OFF SignalAuxiliary heat start/stop calculation Start/Stop CalculationExpansion board Inputs and outputs, software model 05-DX cooling onlyPriority Fault description Reset Keypad Alarm and Fault MonitoringAlarm and fault code summary Compressor Envelope Fault F2 DX Pressure Fault F1Space Temp Sensor Failure F0 Discharge Air DX Cooling Low Limit Indication F3Space Coil DX Temp Sensor Failure F5 Condensate Overflow Indication optional F4Outdoor Temp Sensor Failure F6 Discharge Air Temp Sensor Failure F7Troubleshooting Temperature Sensors Temperature versus resistance Troubleshooting Humidity SensorsHumidity versus voltage Troubleshooting Carbon Dioxide CO2 SensorsCO2 versus voltage table RH % VDC mVConfiguration Parameter Name Abr Default LUI Menu UVC configuration parameters OMAbr Default LUI Menu OAD Stroke Time Warranty