HV_CTL Heating Valve Control - Operation Manual - ELC.E14 - EM1.8D - EM1.8R - EM1.8U

Description

This function block set uses PID to control an analog heating valve in four-pipe air conditioning unit coil application: When hot water passes through the independent heating coil, the heating valve adjusts output counter-proportionally according to the current temperature value and setpoint. It also has a low limit temperature protection function, which requires the heating valve to be fully open for winter heat and freeze protection.

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 %.

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

Function

When "Fan Command" is "1" (0-OFF/1-ON) and "Sensor Fault Alarm" is "0" (0-OK/1-FLT), "Heating Valve Adjustment Control" is calculated based on PI inverse proportion, ranging from 0 % to "Maximum Output".

At any time when "Heating Valve Mode Select" is "0" (0-MAN/1-AUTO), "Heating Valve Adjustment Control" is "Valve Manual Setpoint".

When heating valve is working and "Low Limit Temperature" is "1", "Heating Valve Adjustment Control" is 100 %.

When "Fan Command" is "0" (0-OFF/1-ON) or "Sensor Fault Alarm" is "1" (0-OK/1-FLT), "Heating Valve Adjustment Control" is 0 %.

The output priority is: Low limit temperature protection > Manual mode > Sensor fault alarm > Normal PID calculation output in automatic mode.

Internal logic

Input

Output

Example