How it Works
Danfoss
Loading...
AKC 25H1
Description
24 pgs444.84 Kb0

Danfoss AKC 25H1 Description

RC.1J.Z3.02 → RC.1J.Z4.02 09-1999
Compressor Pack Controller
AKC 25H1
ADAP-KOOL
®
Function description
Contents
Introduction............................................................................................................................... 3
Operation .................................................................................................................................. 4
System information ................................................................................................................. 4
Language .................................................................................................................................. 4
Capacity regulation of compressor........................................................................................ 5
Regulation...................................................................................................................... 5
External displacement of reference ...............................................................................5
Neutral zone and regulating band................................................................................. 6
Compressor definition .................................................................................................... 6
Time delays for cut ins and cut outs............................................................................... 6
Sequence for cut in and cut out of capacity ...................................................................7
Signal from the compressor's safety controls ................................................................ 7
Hourmeter ......................................................................................................................8
Temperature sensor ....................................................................................................... 8
Forced control of compressor capacity ..........................................................................8
Capacity regulation of condenser .......................................................................................... 9
Regulation...................................................................................................................... 9
Neutral zone and regulating band................................................................................. 9
Condenser definition ...................................................................................................... 9
Signal from the condenser's safety controls ................................................................ 10
Hourmeter ....................................................................................................................10
Forced control of condenser capacity.......................................................................... 10
Overriding ............................................................................................................................... 11
Monitoring ............................................................................................................... 12
Monitoring of maximum discharge gas temperature ........................................ 12
Monitoring of maximum discharge pressure .................................................... 1 2
Monitoring of minimum suction pressure......................................................... 13
Monitoring of suction gas superheat................................................................ 13
Monitoring of the different parts of the compressor's safety circuit..................1 4
Monitoring of other automatic controls ............................................................ 14
Supply voltage ........................................................................................................................15
Function switch ...................................................................................................................... 15
Clock function ........................................................................................................................ 15
Refrigerant..............................................................................................................................16
Service....................................................................................................................................17
System measurements/data ................................................................................................ 18
Alarms and messages .......................................................................................................... 19
Access codes ........................................................................................................................ 23
Supporting text .......................................................................................................................23
Installation considerations ................................................................................................... 23
List of literature ...................................................................................................................... 24
This function description was revised in September 1999 and applies to AKC 25H1 with code numbers 084B2017 and 084B2018.
Validity
AKC 25H1 Function description RC.1J.Z4.02 © Danfoss 09/1999 3
Introduction AKC 25H1 is a complete control unit for capacity regulation of compressors and condensers
in commercial refrigeration. The controller can be used in combination with other controllers in the Danfoss ADAP-KOOL
®
refrigeration control system. In addition to capacity regulation the controller can transmit signals to other controllers about operating conditions, e.g. forced closing of expansion valves, alarm signals and alarm messages.
The controller’s main function is to control the compressors and condensers, so that they will constantly operate at the optimum pressure conditions from an energy point of view. Both suction pressure and condensing pressure will be controlled by signals from pressure transmitters type AKS 32.
Among the various functions can briefly be mentioned:
- It can control a total of nine capacity steps distributed on compressor steps and condenser steps, as required.
- There are nine digital imputs for monitoring the various automatic controls. The inputs can be defined to monitor compressors, condensers or other ON/OFF signals, at your option. If failure of a compressor is registered, the controller will control the capacity with the remaining compressors.
- When the compressors stop, signals may be transmitted to the electronic expansion valves, so that they close.
- LED’s on the front plate show the status of outputs and inputs.
- Alarm signals can be generated directly from the controller and via DANBUSS Data Communication.
- Alarms are displayed with texts, so that it is easy to see the cause of the alarm.
The monitoring of a compressor’s safety circuit may be extended from being a simple type of monitoring to a more differentiated monitoring of several parts of the safety circuit. To achieve this, the controller must be linked up with an alarm module type AKC 22H. This alarm module will then receive signals from the different parts of the safety circuit and will subsequently give an exact report on the exact location of the problems in the circuit.
Controller type AKC 25H1 is a unit in the ADAP-KOOL® refrigeration control system. The controller can be linked up with other controllers in the system via a two-core connection - the DANBUSS Data Communication. Through this connection information can be transmitted between the units, like settings, measurements, alarms etc.
Remote service
The different messages and alarms can, via the telephone network, be transmitted by modems to, say, a service company.
Address coding
An address code must be set by means of a number of switches on the controller’s front plate. There are seven switches for the coding. How coding is performed is explained in the installation instructions for the data communication cable (literature No. RC.0X.A).
Connection of control panel type AKA 21
A plug for the connection of control panel AKA 21 is mounted right on the front plate of AKC 25H1. (If the control panel is to be used in any other place, a terminal box will have to be installed (cf. the installation instructions for the data communication cable, literature No. RC.0X.A).)
Data communication
To obtain correct data communication it is important that the installation instructions for the data communication cable be adhered to (literature No. RC.0X.A).
The controller can be operated in two different ways. Either by using control panel type AKA 21 or by means of a PC with system software type AKM.
AKA 21 operation
Setting of the different functions is performed via a menu system. The menu system is built up on several levels where you change around between the different menus by means of arrow keys.
The complete list of menus is contained in the document “Menu operation via AKA 21”. (Cf. list of literature).
PC operation
Operation takes place from a PC where Microsoft-Windows and System Software type AKM have been installed. (The PC is connected to the system via Gateway type AKA 243/244).
Setting of the different functions is performed by means of rolling menus and dialogue boxes. Settings can either be made via the keyboard or by using a mouse.
For users of AKM system software the complete list of menus is found in the document “Menu operation via AKM”. (Cf. list of literature).
There are three languages in the controller. Depending on the code number selected, the languages are either: English, German and French or English, Danish and Spanish. When the required language has been selected, the individual functions will be shown in this language, both when there is operation via AKA 21 and system software type AKM. NB! When you operate system software type AKM it is important that the language code is set before an upload of the controller’s data is carried out to the AKM programme (it is the set language that will be picked up by the AKM programme). Select one of the controller’s three languages by means of the following settings: 0: English 1: German 2: French 3: Danish 4: Spanish Activate the selected language by pushing "Enter" and then push "Clear".
Main Function Main Function Settings Language___
System information
Operation
Language
AKC 25H1 Function description RC.1J.Z4.02 © Danfoss 09/1999 5
The step regulator in the controller can control up to nine capacity steps that can be distributed on one, two or more compressors. (The controller has a total of nine relay outputs that have to be distributed between compressor steps and condenser steps).
Regulation
The cut in compressor capacity is controlled by the actual value of the suction pressure and whether the pressure is rising or falling.
- In the neutral zone there is no cut in/cut out of capacity steps.
- In the “+zone” and “-zone” bands cut in/cut out will depend on whether the pressure is rising or falling. Cut in/cut out takes place with the selected time delays.
- In the “++zone” and “--zone” bands cut in/cut out takes place with the selected time delays.
- Refrigeration is stopped at pressures that are lower than the set “limit” value. (Cf. section on “monitoring”).
Control reference The regulation is based on the set value and the pressure measured by pressure transmitter PO.
Compressor Capacity Ctrl. Settings Compressor Ctrl. P0 SP °C ___
External displacement of reference
The reference for the regulation can be displaced by means of two functions:
1. An external voltage signal transmitted to the “EXT.REF” terminal. The voltage must be 0-10 V.
With this signal the reference can be displaced by up to 50 K in positive or negative direction. 10 V gives max. displacement. The reference change is damped with a time constant of approx. 300 seconds.
Compressor Capacity Ctrl. Settings Compressor Ctrl. K1 Gain K ___
New reference = set reference + voltage signal x “K1 Gain K”/10
2. A night setback signal connected to terminal “S6”. The signal must short circuit the input.
With this signal the reference can be displaced by up to 25 K in positive or negative direction. (Cf. also later section “Temperature sensor”). The reference change is damped with a time constant of approx. 300 seconds.
Compressor Capacity Ctrl. Settings Compressor Ctrl. Night Ref. K ___
The “Forced Nght” signal can also be generated via a setting in the controller.
Compressor Capacity Ctrl. Settings Compressor Ctrl. Forced Nght OFF/ON ___
(This setting can also be made from a mastergateway’s override function).
New reference = set reference + voltage signal x “K1 Gain K”/10 + “Night Ref.K”.
Capacity regulation of compressor
Neutral zone and regulating band
Neutral zone is set. +zone and -zone bands are set. Time delay in +zone and -zone band is set. Time delay in ++zone and --zone band is set.
Compressor Capacity Ctrl. Settings Compressor Ctrl. NZ K ___
+Zone K ___ +Zone s ___ ++Zone s ___
-Zone K ___
-Zone s ___
- -Zone s ___
Compressor definition
The controller can regulate up to nine compressor steps distributed on one, two or more compressors. (If all nine steps are used for compressor control, there is no room left for the control of condenser steps). The controller is based on all the connected compressor steps being equally sized but this is not a requirement. The compressor steps must be defined in groups, so that the controller will know which steps belong to compressor 1, which to compressor 2, etc. This definition is made by setting relay outputs DO1 to DO9. For each relay output you select the compressor that is to belong to it. If several are selected with the same compressor number, it will be the relay with the lowest number that stops and starts the compressor. The subsequent relays will control the individual unloaders.
Output Configuration DO Relay No. ( ) DO( ) Type = 1(1=compressor)
DO( ) Dev. No
Example: A system consists of two compressors. One with three steps and one with two steps. The definition here is performed, as follows:
Output Configuration DO Relay No. 1 DO1 Type = 1(1=compressor)*
DO1 Dev. No = 1 DO2 Type = 1(1=compressor)
DO2 Dev. No = 1 DO3 Type = 1(1=compressor)
DO3 Dev. No = 1 DO4 Type = 1(1=compressor)*
DO4 Dev. No = 2 DO5 Type = 1(1=compressor)
DO5 Dev. No = 2
The two relay outputs marked with a * will start and stop the compressors, and the others will cut in and cut out the unloaders.
Time delays for cut ins and cut outs
To protect the compressor motor against frequent restarts, two time delays can be set.
- a minimum period which shall pass from a compressor starts till it can be restarted.
- a minimum period (on-time), during which the compressor must be operating, before it can be stopped again (to avoid a cutout before the suction pressure has had time to become stable). The setting ranges are from 0 to 25 minutes.
Output Configuration DO Relay No. ( ) DO( ) Recy m ___
DO( ) ON m ___
AKC 25H1 Function description RC.1J.Z4.02 © Danfoss 09/1999 7
Sequence for cut in and cut out of capacity
The sequence for cut in and cut out of capacity can be defined in two ways. Either with a fixed defined sequence or with automatic equalisation of run time between the connected compressors. The sequence will be established by the following setting:
1. Sequential (Step Mode = 1). In general the numbers with which the different compressors are defined will establish the sequence for the cut ins (the compressor defined with a low number will start before a compressor with the next number). The sequence for the cut outs will furthermore be established by the compressor type: Compressors with one step
The sequence is not changed (last cut in step will be cut out first, when the required capacity drops again).
Compressors with several steps
When there are cut outs, the steps on the borderline between the two compressors will be changed around. The function will produce the effect that the last started compressor will not stop until the control has cut out the “last” step of the previous compressor. Example:
Cut in Cut out
2. Automatic equalisation of run time between compressors (Step Mode = 2). This setting should only be used if capacities of the same size are cut in or out but it is not a requirement. (Regulation can also be carried out on compressors with several steps).
- At the different starts, the compressor with the lowest amount of run time will be started
first.
- At the different stops, the compressor with the highest amount of run time will be stopped
first.
- For compressors with several steps there will be no changes of the steps, as is the case
with sequential cut ins and cut outs.
Compressor Capacity Ctrl. Settings Compressor ctrl. Step Mode 1 / 2
Signal from the compressor's safety controls
The controller requires a signal on the status of each compressor’s safety circuit. The signal taken directly from the safety circuit is connected to a “DI” input. This input is a 230 V a.c. input.
(The safety circuit must stop the compressor without the help of AKC 25H1).
If the safety circuit is broken, the controller will cut out all output relays for the compressor in question and give an alarm. The other compressors will continue the regulation. (A broken circuit at the DI input cuts out the outputs). An input from a compressor and the compressor’s number are defined.
Input Configuration Alarm input No. 1..9 DI( ) Type = 1(1=compressor)
DI( ) Dev. No. ___ (compressor No.)
A time delay has to be defined in connection with all alarms. It covers the period of time from the cut out moment until the alarm is registered.
Input Configuration Alarm input No. 1..9 DI( ) Del. m ___
The alarm message concerning a failure in the safety circuit can be extended into a more concrete message by using alarm module type AKC 22H. Read the later section on monitoring.
Hourmeter
The run time of a compressor motor is constantly registered. It can be shown on the display how many hours the compressor has been operating since the hourmeter was last reset, and how many starts there have been during the past 24 hours. (About resetting, see later).
Compressor Status Compressor No.( ) ( ) Run time Compressor Status Compressor No.( ) ( ) Cut / 24 h
All relay outputs are registered by a counter. The run time is registered here for whatever has been connected to the output. This registration can be shown on the display, and reset, if required.
Output Configuration DO Relay No.( ) DO( ) Time h
The hourmeter range is from 0 to 30,000 hours.
Temperature sensor
The controller has an input, S6, for temperature measurement. The measurement has no influence on any regulating functions. The input is, however, used for the night setback signal when the regulation has to change between two different suction pressures. (A short circuited input raises the suction pressure). If data are to be logged from the input, it cannot at the same time be used as signal input for the change between the two suction pressures. The service function is used for displaying the temperature values.
Service Mode Measurements of input terminals S6 °C
Forced control of compressor capacity
There can be forced control of the capacity where the normal regulation and the safety function are disregarded. The capacity is set in per cent of the regulated capacity.
Compressor Capacity ctrl. Settings Compressor ctrl Man. Cap OFF/ON
Man. Cap. % ___
Compressor control, but no condenser control
The controller is normally used for controlling both the compressor and the condenser. If the controller is only used for controlling the compressor, a missing signal at the pressure transmitter input Pc will trigger an alarm signal. To avoid this alarm, a signal can be picked up from pressure transmitter PO. Connect terminal 72 to 76 (“s” to “s”). The monitoring function for PCmax must be set at the highest possible value.
Loading...
+ 16 hidden pages
Buy Points How it Works FAQ Contact Us Questions and Suggestions Privacy Policy Cookie Policy Terms of Use