Festo PDAD Series Installation and operating instructions

100152
Application note
Energy management function at
adsorption dryer PDAD
Application note for use of the energy management function at
adsorption dryer PDAD. Explanation, use and layout of purge air
regulation for reducing air consumption.
PDAD-…-…

Title ...................................................................................Energy management function at adsorption dryer PDAD
Version.............................................................................................................................................................. 1.10
Document number ....................................................................................................................................... 100152
Original ................................................................................................................................................................ de
Author ..............................................................................................................................................................Festo
Last saved on ........................................................................................................................... 20. September 2017
Copyright notice
This documentation is the intellectual property of Festo AG & Co. KG, which also holds exclusive copyrights. Any
modification of the content, duplication or reprinting of this documentation, as well as distribution to third parties,
are only permissible with the express consent of Festo AG & Co. KG.
Festo AG & Co KG reserves the right to make modifications to this document in whole or in part. All brand names
and product names are trademarks or registered trademarks of their respective owners.
Legal notice
Hardware, software, operating systems and drivers may only be used for the applications described and only in
conjunction with components recommended by Festo AG & Co. KG.
Festo AG & Co. KG does not accept any liability for damages arising from the use of any incorrect or incomplete
information contained in this documentation or any information missing therefrom.
Defects resulting from improper handling of devices and modules are excluded from the warranty.
The data and information specified in this document should not be used for the implementation of safety-relevant
functions for the protection of personnel and machinery.
No liability is accepted for claims for damages arising from failure or malfunctioning. Otherwise, the stipulations
concerning liability set forth in the terms and conditions of delivery, payment and use of software of Festo AG &
Co. KG, which can be found at www.festo.com or can be supplied upon request, shall apply.
None of data contained in this document represent guaranteed characteristics in the legal sense, particularly with
regard to functionality, condition or quality,.
The information in this document serves only as basic information for the implementation of a specific,
hypothetical application and is in no way intended as a substitute for the operating instructions of the respective
manufacturers or design and testing of the respective application by the user.
The respective operating instructions for Festo products can be found at www.festo.com/sp.
Users of this document (function and application) must themselves verify that all of the functions described herein
also work correctly within the application. Even after examining this document and using the specifications
contained herein, users are nevertheless solely responsible for their own applications.
(Festo AG & CO. KG, D-73726 Esslingen, Germany, 2017)
Internet: http://www.festo.com
E-mail: [e-mail]

Table of contents
Application Note –Energy management function at adsorption dryer PDAD –1.10 Page 3 of 17
Table of contents
1Utilised components, documentation......................................................................................................... 4
1.1 Utilised components.................................................................................................................................... 4
1.2 Documentation............................................................................................................................................ 4
2 Description and purpose of the application note ......................................................................................... 5
2.1 Introduction to the subject matter............................................................................................................... 5
2.2 PDAD functions............................................................................................................................................ 6
2.3 Reasonably foreseeable misuse.................................................................................................................. 7
2.4 Environment used in.................................................................................................................................... 7
2.5 User groups................................................................................................................................................. 7
2Layout of purge air regulation for reducing air consumption..................................................................... 8
3.1 Nature of the task........................................................................................................................................ 8
2.2 Use of a manual switch for purge regulation ............................................................................................... 9
2.3 User of a dew point transmitter and a process regulator for purge regulation .......................................... 10
2.4 Use of a simple pressure switch for purge regulation ............................................................................... 11
2.5 Use of a pressure sensor for purge regulation .......................................................................................... 13
2.6 Establishing a connection between switching device and the energy management contact at the PDAD . 14
3Safety........................................................................................................................................................ 17

Utilised components, documentation
Application Note –Energy management function at adsorption dryer PDAD –1.10 Page 4 of 17
1Utilised components, documentation
1.1 Utilised components
Type/name
Software/firmware version
Date of manufacture
PDAD-…-…
All
All
Manual electric switch
--
--
dew point sensor/transmitter
--
--
Pressure switch
--
--
Pressure sensor
--
--
Table 1: Utilised components
1.2 Documentation
This application note is intended to supplement existing documents to include the energy management function.
Catalogue documentation
https://www.festo.com/cat/en-gb_gb/data/doc_engb/PDF/EN/PDAD_EN.PDF
Operating instructions:
https://www.festo.com/net/en-gb_gb/SupportPortal/Downloads/385765/464376/PDAD_2017-
01g_8068816g1.pdf
Animation:
https://www.festo.com/net/en-gb_gb/SupportPortal/Flash/378325/376353/en/index.htm
--> Further documents and publications regarding this subject can be found at the Support Portal operated by
Festo AG & Co. KG.

Description and purpose of the application note
Application Note –Energy management function at adsorption dryer PDAD –1.10 Page 5 of 17
2 Description and purpose of the application note
2.1 Introduction to the subject matter
The adsorption dryer PDAD is used to reduce the pressure dew point to -70° C for corresponding use, e.g. handling
powders, in climatised rooms and in the pharmaceuticals and chemicals industries.
Brief explanation:
Adsorption (from the Latin adsorpio, from adsorbere (“draw in”) is the designation for the enrichment of
substances from gases or liquids at the surface of a solid, generally at the interface (matter) between two phases.
Adsorption dryers draw the moisture out of the compressed air through the use of a drying agent. While
adsorption takes place in the first container, regeneration takes place in the second container at the same time.
The cycle times are stored in the electronic controller. Pressure dew points within a range of -20 to -70 °C are
achieved with standard products. Various hot and cold processes are available for regeneration.
The cold regeneration process is used by the adsorption dryer PDAD:
For the purpose of regeneration, a portion of the already dried compressed air is caused to flow through the
previously used container cartridge and is then vented to the atmosphere.
+Simple technology
+Minimal investment costs
- Compressed air consumption
-High operating costs

Description and purpose of the application note
Application note –Energy management function at adsorption dryer PDAD –1.10 Page 6 of 17
2.2 PDAD functions
Due to requirements for minimal power consumption, the PDAD is equipped with an energy management function.
This makes it possible to set up purge air regulation with corresponding interconnection in order to reduce air
consumption. The PDAD also includes an RJ45 interface for connecting a PC directly via a network cable (Ethernet).
With the help of software matched to the serial number, the dryer’s setting can be accessed and changed, and
errors can be read out if applicable.
These functions are integrated, but they’re not described in the operating instructions. The software is neither
provided by Festo nor is it available, because the device can be damaged in the event of incorrect settings.
The PDAD is also equipped with an alarm connection which is described in the operating instructions. A visual or
acoustic remote alarm system can be connected outside of the dryer via this connection (type C DIN plug). In the
event of a malfunction or if service is required, the alarm relay is switched (NO contact) and red LEDs
simultaneously indicate the error at the display panel. The alarm relay is reset when the error has been eliminated,
but only after the current switching cycle has been completed or the control device has been reset after a cartridge
change.
Figure 0: PDAD functions –overview of connections at the controller
Connection for energy
management function
Controller serial number
Connection for alarm function
Service interface connection

Description and purpose of the application note
Application note –Energy management function at adsorption dryer PDAD –1.10 Page 7 of 17
2.3 Reasonably foreseeable misuse
This application note describes the layout and the benefits of the energy management function. It can be used to
shut down the purge air function when little or no air is required.
It’s very important to understand that the purge function can only be shut down at times when little or no air is
required. If this function is shut down at any other time, the drying agent cartridges may be permanently damaged
thus resulting in the loss of drying performance, and possibly a mechanical defect as well. The cartridges may
never be entirely saturated!
In any case, checking must be conducted for continuously flawless functioning because the dryer might
otherwise fail, or errors might occur within the process or the application!
The function of the RJ45 interface for direct connection of a PC via a network cable (Ethernet) is not described
because the software is not supplied with the product, and there are too many hazards associated with incorrectly
configured device parameters. The function and use of the alarm connection are described in the official operating
instructions.
2.4 Environment used in
•Industrial environment
•Applications with minimal or sporadic air consumption with correspondingly specified
pressure dew points, e.g. in laboratories
2.5 User groups
•Specialists in the field of pneumatics
•Specialists in field of electrical engineering
•Sales engineers at Festo AG & Co. KG

Layout of purge air regulation for reducing air consumption
Application Note –Energy management function at adsorption dryer PDAD –1.10 Page 8 of 17
2Layout of purge air regulation for reducing air consumption
3.1 Nature of the task
Regenerative dryers have to eject a portion of the process air in order to remove the moisture which accumulates
inside them. During times when only small amounts of air are required, this loss is unnecessary and thus
undesirable. In many cases the compressor runs nearly uninterruptedly in order to compensate for the dryer’s
purge air loss.
Example: The compressor for central compressed air preparation is started up again and again due to the purge
air function and the associated pressure drop, although no air consumption is required for the application.
Compressor start-up results in noise –in some cases disagreeably at night. The temperature in the room might
also rise, so that applications with low pressure dew points may be influenced.
The adsorption dryer PDAD is equipped with an energy management function by means of which the purge
function can be shut down during times when little or no air is required. The dryer’s regulator is equipped with a
set of easily accessible contacts with which the solenoid valves (which regulate the dryer’s purge function) can be
shut down, thus resulting in zero air loss at via dryer.
In order to makes use of this function, the operator must provide a switching system with acceptable logic which
informs the dryer when little or no air is required. Several examples of frequently used switching systems are
provided in the following pages (with varying complexity).

Layout of purge air regulation for reducing air consumption
Application note –Energy management function at adsorption dryer PDAD –1.10 Page 9 of 17
2.2 Use of a manual switch for purge regulation
This is the simplest setup. When air is not used downstream from the dryer, the purge function is shut down by
means of a manual switch. This layout is frequently used in systems which act upon the point of consumption
(point-of-use or POU systems). For example, if the dryer is only used to supply suitably dried air to a certain
machine or application, the dryer is only needed when the machine is running and can be shut down either
manually or possibly via additional contacts in the machine’s on/off switch.
It’s very important to understand that the purge function can only be shut down at times when little or no air is
required. If this function is shut down at any other time, the drying agent cartridges may be permanently damaged
thus resulting in the loss of drying performance, and possibly a mechanical defect as well. The cartridges may
never be entirely saturated!
The following drawing (figure 2) shows how the above mentioned components might be connected for regulation
of a dryer’s purge function. Please note that specific details regarding the components are manufacturer-
independent –the manufacturer’s specifications must be complied with in any case.
Figure 2: Use of a manual switch for purge air regulation
Dryer
regulator
Pin 2
Pin 1 (reads out +5 V DC signal)
Manual switch
(installed in the field)
Signal output
Return signal
* Current-free when closed –open to deactivate the purge function
Current-free
when closed *

Layout of purge air regulation for reducing air consumption
Application note –Energy management function at adsorption dryer PDAD –1.10 Page 10 of 17
2.3 User of a dew point transmitter and a process regulator for purge regulation
The best alternative for purge regulation when the degree of dryness (pressure dew point) of the air from the
dryer is critical. When the air is adequately dry, the purge function can be shut down until moisture in the air
increases once again. When the purge function is shut down, it must be assured that the drying agent beds don’t
become too wet before purge function is restarted. When the purge function is switched back on again, the air’s
pressure dew point may continue to climb a bit before it drops off again. This must be taken into consideration in
order to assure that the flow of air remains adequately dry.
It’s very important to understand that the purge function can only be shut down at times when little or no air is
required. If this function is shut down at any other time, the drying agent cartridges may be permanently damaged
thus resulting in the loss of drying performance, and possibly a mechanical defect as well. The cartridges may
never be entirely saturated!
The following drawing shows how the above mentioned components might be connected for regulation of a
dryer’s purge function. Please note that specific details regarding the components are manufacturer-independent
–the manufacturer’s specifications must be complied with in any case.
Figure 6: Use of a dew point sensor and a process regulator for purge regulation (this setup is only an example and the configuration
can be changed depending on the application)
Dryer
regulator
Pin 2
Pin 1 (reads out
+5 V DC signal)
Signal output
Return signal
* Current-free when closed –open to deactivate the purge function
DC supply power
Electronic
pressure switch
Dew point transmitter
Relay
Signal output
COM
Return signal