[Hum22] Humidifier, humidity-controlled, with limitation controller

Program block, name / node subtype: [Hum22] Humidifier, humidity-controlled, with limitation controller

Library hierarchy: Ventilation and air conditioning equipment

Family: Hum

Project tree	Diagram

Configurator

Program blocks are stored in the library without I/Os. Use the auto-create and auto-connect functions to create I/Os and/or to connect them to the interface blocks, e.g., R_A, CMD_B. Alternatively, take the I/Os from the folder containing the predefined I/Os in the library and/or from the plant and connect them to the interface blocks.

Function

Controls the supply air humidity (humidification) by modulating an output signal to the control unit of a humidifier (OutItf21). Alternatively, a request for different stages can be sent to the humidifier (OutItf22).

The control of the supply air humidity (humidification) is preset to absolute humidity (HuCtr21). It can be changed to relative humidity in the Function configurator.

There is a delay-off time, e.g., 5 minutes, for the signal for the operating state that keeps its value to "True" after the humidifier becomes inactive. If used in an air handling unit plant (which is most likely the case), the operating state of the humidifier is read by CMDSEQ_B. If the plant is about to be switched off and the humidifier was active, then the plant should run for some time with a humidifier switched off to dry it. During the switching-off, CMDSEQ_B receives the operating state "True" for the length of time of this delay and waits before continuing with the further switching-off. This helps to dry it.

This program block has the following optional functions:

Option: Fault (1xBI)

Reads a fault contact and generates an alarm.

Option: Feedback (1xBI)

Reads the feedback signal and generates an alarm if feedback is missing when the humidifier must run.

Option: Humidity detector (1xBI)

Reads the signal from a humidity detector and stops the humidity controller and the outputs.

The event detection is suppressed when the humidifier is off.

Option: Limitation controller

This is a PID controller that limits the output of the humidity controller if the supply air relative humidity reaches, e.g., 80 %.

We recommend this option in case of control for absolute humidity to make sure that the relative humidity does not rise too high.

Option: Maintenance switch (1xBI)

Reads the signal from the maintenance switch and generates an alarm. If active, the outputs are stopped with very high priority (priority 2).

Mandatory elements

Name	Description	Type	Alarm / Notification class	Trend / Type
HuCtr	Humidity controller	[HuCtr21] Humidity controller absolute	N/A	N/A
OutItf	Interface output	[OutItf21] Interface output, activate and modulating output	N/A	N/A

See also

Optional elements

Name	Description	Type	Alarm / Notification class	Trend / Type
Fb	Feedback	BI: Binary input	Yes, 4	No
MntnSwi	Maintenance switch	BI: Binary input	Yes, 5	No
LmCtr	Limitation controller	Ctr: Controller	N/A	N/A
Flt	Fault	BI: Binary input	Yes, 4/5	No
HuDet	Humidity detector	BI: Binary input	Yes, 5	No

See also