OAD_CTL Outside Air Damper Control - Operation Manual - ELC.E14 - EM1.8D - EM1.8R - EM1.8U

Description

This function block set is used to control an analog outside air damper. It controls the damper to be shut down a certain time later after a supply fan is stopped. It also has a low limit temperature function to protect the damper. The analog control of the outside air damper can be reached via preset position or PID-adjusted output, where PID adjustment can be controlled based on CO2, VOC or temperature.

Of all the inputs, Fault Alarm is generated from a PID-adjustable primary sensor. Once there is such an alarm, the PID-calculated output is 0 %. In addition, when the low limit temperature function is activated, the outside air damper is shut down immediately.

This set also has a manually override function. If "Outside Air Damper Mode Select" is "0 - MAN (manual)", the output is "Outside Air Damper Manual Setpoint". If "Outside Air Damper Mode Select" is "1 - AUTO", the output is the automatic logic value of the application.

Note: PID control of CO₂/VOC is direct-proportional and that of temperature is direct-proportional for cooling and inverse-proportional for heating.

Function

When "Outside Air Damper Mode Select" is "1" (0-MAN/1-AUTO), "Unit Start/Stop" is "1" (ON) and "Low limit Temperature" is "0", "Outside Air Damper Control" is the larger value of "Outside Air Damper Pre-set Setpoint" and "Minimum Output".

When "Unit Start/Stop" is "0" (OFF) and "Supply Fan Command" is "0" (OFF) and starts timing until "Damper On-Off Time Delay" has elapsed, "Outside Air Damper Command" is "0 %".

When "Sensor Fault Alarm" is "1" (0-OK/1-FLT), "Outside Air Damper Control" is "0 %".

At any time when "Low Limit Temperature" is "1", "Outside Air Damper Control" is "0 %".

Except for the situation when "Low Limit Temperature" is "1", "Outside Air Damper Control" is equal to "Outside Air Damper Manual Setpoint" without limitation of "Minimum Output" when "Outside Air Damper Mode Select" is "0" (0-MAN/1-AUTO).

When "PRESET/PID" is "0" (PRESET), "Outside Air Damper Control" is "Outside Air Damper Pre-set Setpoint". When "PRESET/PID" is "1" (PID), "Outside Air Damper Control" generates output according to corresponding PID settings.

The output priority is: Low Limit Temperature > Manual mode > "PRESET/PID" selection in automatic mode > Sensor fault alarm > Normal PID output.

Internal logic

Input

Output

Example