Danfoss AK2-SC 255 Reference Manual
AK2-SC 255
Reference Manual
RE FR IG ER ATI ON A ND
AI R CONDITIONING
Users Manual
AK2-SC 255 Rack Controller
System Reference Manual
RS.8D.M1.22 AK2-SC 255 Reference Manual 1
2 AK2-SC 255 Reference Manual RS.8D.M1.22
AK2-SC 255 Rack Controller
System Reference Manual
What this manual
covers This manual covers configuration and operation of the Danfoss AK2-SC 255 Rack
Controller and systems based upon it. In this manual we very often refer to the
controller as “SC 255,’ a shortened version of its official name.
This manual is intended for the user who requires detailed information about any
aspect of the controller’s operation and software.
Although the manual does not at this time have an index, the Table of Contents that
follows this page is quite extensive and should be a useful guide to the text.
Other manuals for
this system Other Danfoss manuals that you should have are the On Site Guide for the AK2-SC
255, which covers installation and start-up of the controller, and the AK2 I/O Module
manual, which details installation and operation of the I/O modules and their software
interface using the AK2-SC 255 and earlier controllers.
If you can, you should check the Danfoss web site at
select the menu item for product literature. The AK2-SC 255 literature will be in the
Supermarket electronics section.
DISCLAIMER Where this manual discusses control and monitoring of equipment not manufactured
by Danfoss, or discusses interface to software not published by Danfoss, the accuracy of the text is in some cases dependent upon information furnished by the manufacturers of such non-Danfoss products, and Danfoss cannot be held responsible for
the accuracy of lthe information. Nevertheless, we have made every effort to ascertain correct information from all parties invol
Copyright © 1999, 2003, 2004, 2005 Danfoss Inc. All rights reserved.
At Danfoss, continuous improvement to documentation goes hand-in-hand
with the product refinement and quality for which Danfoss is justifiably world
famous. We welcome your suggestions for additions or improvements to any
of our manuals or other literature. Please address your comments to:
Danfoss Inc.
Literature Department
7941 Corporate Drive
Baltimore, MD 21236-4925
T elephone: (410) 931-8250
F AX: (410) 931-8256
www.acr.danfoss.com and
RS.8D.M1.22 AK2-SC 255 Reference Manual 3
Table of Contents
P ART ONE Configuration
1.1 Initial Configuration ........................................................................................................1 1 - 12
Introduction ..................................................................................................................................... 11
Battery ..................................................................................................................................... 11
Authorization codes .............................................................................................................................. 11 - 12
Using Menus ..................................................................................................................................... 12
Selection of units and languages ................................................................................................................. 12
1.2 Configuring Refrigeration............................................................................................. 13 - 63
Starting with a partially configured AK2-SC 255........................................................................................ 13
Starting with a completely un-configured AK2-SC 255 .............................................................................. 14
Navigation and making changes.................................................................................................................. 14
Entering numerals ..................................................................................................................................... 14
Entering labels ..................................................................................................................................... 14
Constrained fields .............................................................................................................................. 14 - 15
Configuring Rack Info..........................................................................................................................15 - 16
Adding a rack ..................................................................................................................................... 16
Configuring Suction Info ...................................................................................................................... 16 - 19
Configuring two-stage systems ...................................................................................................... 19 - 20
Configuring compressors...................................................................................................................... 20 - 22
Compressor oil and safety information...........................................................................................22 - 23
Neutral Zone control ............................................................................................................................. 23
Compressor capacity staging patterns ........................................................................................... 24 - 25
Configuring Evaporators ...................................................................................................................... 25 - 31
Case lights button .................................................................................................................................. 27
Configuring AK2-SC 255 refrigeration circuits..................................................................................... 28
Configuring defrost 32 - 33
Configuring evaporators ....................................................................................................................... 33 - 34
Configuring condensers ........................................................................................................................34 - 46
Aircooled condensers..................................................................................................................... 35 - 42
Split condenser control ............................................................................................................. 39 - 40
Reaction zone and time................................................................................................................... 40
Enviroguard systems ...................................................................................................................... 41 - 42
Evaporative condensers .................................................................................................................42 - 47
Pump, louver, and sump schedules...........................................................................................44 - 45
Inverter settings; freeze protection; dump valve...................................................................... 45 - 46
Dump schedules....................................................................................................................... 46 - 47
Receiver configuration ................................................................................................................................ 47
Heat reclaim configuration ...................................................................................................................47 - 49
Refrigeration alarms configuration ....................................................................................................... 49 - 50
Board & Points configuration...................................................................................................................... 50
Navigation ..................................................................................................................................... 51
Board & Points, relay outputs (digital outputs) ..............................................................................51 - 52
Board & Points, sensor inputs (analog inputs) ............................................................................... 52 - 54
Board & Points, on-off inputs (digital inputs)................................................................................. 54 - 55
4 AK2-SC 255 Reference Manual RS.8D.M1.22
Board & Points, variable outputs (analog outputs)...................................................................................... 56
Board & Points, other controllers (case controllers, VFDs, etc., that are on the 255 network) ..........57 - 62
AKC 16x circuits, board & points........................................................................................................ 57
Network re-scan and initialization................................................................................................... 58
Navigation ..................................................................................................................................... 58
EKC circuits, board & points ......................................................................................................... 58 - 60
Network re-scan and initialization............................................................................................59 - 60
Wink ..................................................................................................................................... 60
Degree Master board & points ...................................................................................................... 60 - 61
Locate procedure ............................................................................................................................ 61
Activating the service pin from the display .....................................................................................61
Initialization ..................................................................................................................................... 61
Wink ..................................................................................................................................... 61
VLT and AKD drives, board & points........................................................................................... 61 - 62
DCU circuits, board & points ............................................................................................................... 62
1.3 Configuring HV AC ..........................................................................................................63 - 1 13
Introduction63 - 64
RTU Configuration ..............................................................................................................................64 - 76
R TU fan configuration ................................................................................................................... 64 - 66
RTU cooling configuration .............................................................................................................66 - 69
R TU heating configuration ............................................................................................................. 69 - 72
RTU dehumidification configuration...............................................................................................72 - 75
R TU air damper configuration .......................................................................................................75 - 76
R TU alarms configuration ..................................................................................................................... 76
R TU board & points configuration........................................................................................................ 76
AHU Configuration ..............................................................................................................................76 - 80
AHU fan configuration ..................................................................................................................76 - 78
AHR outside air coil configuration.................................................................................................79 - 80
RTC Configuration ..............................................................................................................................80 - 93
R TC fan configuration....................................................................................................................80 - 83
RTC cooling configuration..............................................................................................................83 - 84
R TC heating configuration ............................................................................................................. 85 - 86
RTC dehumidification configuration............................................................................................... 86 - 87
R TC air damper configuration........................................................................................................87 - 89
RTC schedules ..................................................................................................................................... 89
RTC alarm configuration....................................................................................................................... 89
R TC I/O points configuration ......................................................................................................... 89 - 92
Relay outputs (digital outputs)......................................................................................................... 90
Sensor inputs (analog inputs) ................................................................................................... 90 - 91
On-off inputs (digital inputs) ....................................................................................................91 - 92
RTC I/O variable outputs (analog outputs) ..............................................................................92 - 93
R TC address and Initialization........................................................................................................93 - 94
Seasons 4 Smart Coil configuration......................................................................................................94 - 98
Fan configuration, Seasons 4 Smart Coil............................................................................................... 94
Cooling configuration, Seasons 4 Smart Coil..................................................................................95 - 96
Heating configuration, Seasons 4 Smart Coil ................................................................................. 96 - 97
Dehumidification configuration, Seasons 4 Smart Coil...................................................................98 - 99
Condenser configuration, Seasons 4 Smart Coil ...................................................................................99
Alarms configuration, Seasons 4 Smart Coil......................................................................................... 99
RS.8D.M1.22 AK2-SC 255 Reference Manual 5
Board & points configuration, Seasons 4 Smart Coil ............................................................................ 99
ClimaTECH configuration................................................................................................................ 100 - 109
Fan configuration, ClimaTECH................................................................................................... 100- 101
Cooling configuration, ClimaTECH............................................................................................ 101 - 102
Heating configuration, ClimaTECH ........................................................................................... 102 - 103
Dehumidification configuration, ClimaTECH............................................................................. 103 - 104
Economizer configuration, ClimaTECH .............................................................................................. 104
Alarm configuration, ClimaTECH....................................................................................................... 105
Schedule configuration, ClimaTECH .................................................................................................. 105
I/O configuration, ClimaTECH ........................................................................................................... 105
Relay outputs (digital outputs), ClimaTECH ................................................................................. 106
Sensor inputs (analog inputs), ClimaTECH........................................................................ 106 - 107
On-off inputs (digital inputs), ClimaTECH........................................................................... 107 - 108
Address and Initialization, ClimaTECH ........................................................................................ 108
Uploading ClimaTECH configuration to the AK2-SC 255 .................................................. 108 - 109
1.4 Lighting Configuration ................................................................................................110 - 1 1 4
Beginning configuration ..............................................................................................................................110
AK2-SC 255 lighting zone setup ........................................................................................................110 -11 3
Board & points configuration, lighting ........................................................................................................113
Powerlink configuration..............................................................................................................................113
Cutler-Hammer configuration ....................................................................................................................113
Powerlink and Cutler-Hammer board & point configuration .....................................................................113
Locate procedure ....................................................................................................................................114
1.5 Energy Meter Configuration (including demand limiting) .......................................114 - 121
Installation ....................................................................................................................................114
Configuration ...........................................................................................................................114 - 118
W attnode Plus configuration ......................................................................................................................118
About soft starts ....................................................................................................................................119
Configuring demand limiting ............................................................................................................... 119-121
HV AC demand limiting .............................................................................................................. 119 - 120
Lighting demand limiting...................................................................................................................... 120
How demand limiting works....................................................................................................... 120 - 121
1.6 Configuring Alarms...................................................................................................... 121 - 140
The Configure Alarms menu..................................................................................................................... 121
Configuring refrigeration alarms ...................................................................................................... 122 - 135
Alarms suspended ...............................................................................................................
....... 123 - 124
Suspending rack alarms ...................................................................................................................... 124
Configuring alarm settings.......................................................................................................... 124 - 126
Analog alarms .......................................................................................................................... 126 - 127
Field limits and units for analog alarms ......................................................................................... 127
Disabling alarms ................................................................................................................................... 127
What alarms are needed? ......................................................................................................................... 127
(Some) Frequently Asked Questions.................................................................................................. 127-128
T ypes of suction alarms, listed .................................................................................................................. 128
Compressor alarms .......................................................................................................................... 128 - 129
Circuit alarms .......................................................................................................................... 129 - 132
AK2-SC 255 circuits.................................................................................................................. 130 - 131
AKC 164 circuits ....................................................................................................................... 131 - 132
6 AK2-SC 255 Reference Manual RS.8D.M1.22
1.6 Configuring Alarms (continued)........................................................................... 121 - 132
EKCK, DCU, and Degree Master circuits......................................................................................... 132
AKC 165 subcooling circuits............................................................................................................... 132
Condenser alarms ................................................................................................................................... 133
“Other” rack alarms ............................................................................................................................ 134
Configuring Bitzer rack alarms ........................................................................................................ 134 - 135
HVAC alarm configuration .............................................................................................................. 135 - 138
AHU, RTU, and SC4 alarms .............................................................................................................. 136
RTC alarms ................................................................................................................................... 137
ClimaTECH alarms....................................................................................................................137 - 138
Miscellaneous alarms ....................................................................................................................... 138 - 140
Example miscellaneous alarm .................................................................................................... 139 - 140
Number of alarms field ....................................................................................................................... 140
1.7 Miscellaneous Points Configuration......................................................................... 140 - 154
Starting configuration ................................................................................................................................141
Plan strategy first ................................................................................................................................... 141
Miscellaneous relay outputs ............................................................................................................. 141 - 142
Miscellaneous sensor inputs ...................................................................................................................... 142
Miscellaneous on-off inputs....................................................................................................................... 142
Specifying miscellaneous conversiosn.............................................................................................. 142 - 143
Miscellaneous calculations ............................................................................................................... 143 - 144
Point creation .......................................................................................................................... 144 - 145
Custom strategy example ................................................................................................................. 145 - 153
Creating the miscellaneous points -- Sensor inputs .................................................................... 145 - 146
Writing the custom strategy ................................................................................................................ 146
Data definitions .......................................................................................................................... 146 - 148
The rules area .......................................................................................................................... 148 - 149
Writing rules .......................................................................................................................... 149 - 150
Creating the miscellaneous points relay output ........................................................................... 151- 154
Configuring Authorization........................................................................................................... 154
Configuring Units and Languages ............................................................................................. 155
PART TWO Using the Status Screens and Service Functions
Authorization -- “Just Looking” .............................................................................................................................. 157 - 158
Geeting Authorized to make changes ...................................................................................................................... 158 - 159
Units and Languages -- Selecting .................................................................................................................................... 159
2.1 Navigation and Making Changes ............................................................................. 159 - 164
Getting back to the icon menu................................................................................................................... 162
Viewing and changing setting.................................................................................................................... 162
Changing numeric values .......................................................................................................................... 162
Changing list fields .................................................................................................................................. 163
Changing the “From” and “T o” times ....................................................................................................... 163
Changing the days of the week and holidays ............................................................................................ 164
Changin g label fi elds ................................................................................................................................. 164
RS.8D.M1.22 AK2-SC 255 Reference Manual 7
2.2 Using the Service Screens....................................................................................... 165 - 167
Auto/Manual Relays ....................................................................................................................... 165 - 166
<Reset> ................................................................................................................................... 166
Sensor adjustment ................................................................................................................................... 166
Maintenance hours ..........................................................................................................................166 - 167
Bd/Pt locations ................................................................................................................................... 167
2.3 Using the Smart Case Controller Screens............................................................... 168 - 174
Introduction .......................................................................................................................... 168 - 171
Evaporator settings .......................................................................................................................... 171 - 172
Evaporator schedules ................................................................................................................................ 172
Evaporator service .......................................................................................................................... 172 - 174
Manual operation........................................................................................................................ 172 - 173
AKC 16x shutdown ............................................................................................................................ 173
Case cleaning .......................................................................................................................... 173 - 174
2.4 Using the Refrigeration Screens for Refrigeration Circuits.................................. 174 - 175
Evaporator Status screen ................................................................................................................. 174 - 175
Evaporator settings screen ........................................................................................................................ 175
Evaporator Schedules screen, Evaporator Alarms screen, and Evaporator Service screen ..................... 175
2.5 Using the Communications Screens......................................................................... 176 - 187
Host Network screen ................................................................................................................................ 176
I/O Network Status screen .............................................................................................................. 176 - 177
List Points .......................................................................................................................... 177 - 179
List Nodes .......................................................................................................................... 179 - 180
IP Network (Ethernet) ..................................................................................................................... 180 - 181
Alarm routing for Ethernet ............................................................................................................... 181 - 182
Printer Settings screen ..................................................................................................................... 182 - 183
Modem configuration ....................................................................................................................... 183 - 186
Messages screen ................................................................................................................................... 186
2.6 Using the History Screens (for History Retrieval) .................................................. 187 - 192
Selecting points to view............................................................................................................................. 189
Displaying history .......................................................................................................................... 189 - 191
Graphing history .......................................................................................................................... 191 - 192
Stat (for statistics) ................................................................................................................................... 192
2.7 Using the Alarms Screens.......................................................................................... 193 - 197
The Alarms menu .......................................................................................................................... 193 - 194
The Active Alarms screen ............................................................................................................... 194 - 195
The Cleared Alarms screen ...................................................................................................................... 195
The Alarm Status screen.................................................................................................................. 195 - 196
The Network Alarms screen ..................................................................................................................... 196
The Alarm Service screen ............................................................................................................... 196 - 197
2.8 Overrides ............................................................................................................ 198 - 200
Overrides using service screens ........................................................................................................ 198-199
Overriding sensor values ........................................................................................................................... 199
Overrides using RO8S switches .............................................................................................................. 199
8 AK2-SC 255 Reference Manual RS.8D.M1.22
Overrides using the Manager’s Override box.................................................................................. 199 - 200
Keyswitch Override for refrigeration high temperature alarms................................................................ 200
2.9 Using the Audit Trail................................................................................................... 200 - 202
RS.8D.M1.22 AK2-SC 255 Reference Manual 9
10 AK2-SC 255 Reference Manual RS.8D.M1.22
PART ONE
Configuration
1 - 1. Initial Configuration
Battery The unit’s backup battery power is automatically enabled when the unit is first
Note: We use the formal type designation “AK2-SC 255” occasionally in this manual, but
most often you will see the short form of the name: “SC 255.”
Configuration of an AK2-SC 255 is easy using the keypad and display, and even
easier using Danfoss AKA 65 Network Interface software running opn a PC connected to the controller. This chapter describes configuration from the AK2-SC 255
keypad. You can easily adapt these instructions for the PC keyboard and mouse after
reading Chapter 3, “Using AKA 65 Software on Your PC.”
We will address configuration of each area of a supermarket control system in this
section of the manual. Initial configuration for equipment start-up may be limited to
such items as are necessary to check out the mechanical equipment or provide basic
service. The configuration can be changed or added to at any time later.
externally powered. Note that if you receive the unit partially configured, the battery
will have been enabled. Normal battery life is a minimum of ten months, but the
battery is only used when main power is interrupted. In a unit which rarely experiences power interruptions, the battery can last as long as eight years.
If the battery is disabled (by removing it, or when it ultimately discharges completely)
any information stored in the unit (set points, schedules, etc.) will be lost. Do not
remove the battery.
Authorization codes When the SC 255 is turned on for the first time, the Main Menu will appear as at left
below:
Before you can enter configuration information, you must select Authorization and
RS.8D.M1.22 AK2-SC 255 Reference Manual 1 1
enter a valid authorization code and account code. Using the right arrow , move the
cursor to Authorization and press ENTER. The Authorization Menu will appear as
at right above, with the cursor in the Auth field.
When you have entered the access code and account number given to you by the
system owner, you will see the words Authorization accepted appear briefly in
reverse video at the very bottom of the screen. In the upper right, the screen will
show what the authorization level is.
After initial configuration, you will be able to make changes by several different
avenues, which are discussed in Chapter 5, “Using the System.”
Using menus To select from any SC 255 menu, first use the arrow keys to move the cursor to the
item you want, then press the ENTER key. You can use the EXIT key to retrace
your steps level by level.
Selection of Units
and Language Before using the system, you may wish to change the language used on the screens,
the units used for pressure and temperature, or the date and time format. These
settings will be for the local PC only, and will not af fect the displays of any SC 255 in
the system. To change the displayed units, select Store Information from the main
menu and then choose Units/Languages. In the Configuration Units/Languages
screen, select the language you want to see in the controller screens, then select
either psi or bar for pressure; either °F or °C for temperature; and either % or fc
(footcandles) for light level.
12 AK2-SC 255 Reference Manual RS.8D.M1.22
1 - 2. Configuring Refrigeration
There are two “routes” you may need to navigate to begin configuring refrigeration.
One begins by selecting Refrigeration from the Main menu, and the other by
selecting Configuration.
Starting with a
Partially Configured
AK2-SC 255 If the AK2-SC 255 you are working with was supplied with a rack, the controller may
have been partially configured by the rack manufacturer. In that case, when you
select Refrigeration from the Main Menu, the SC 255 will display the Refrigeration
Menu (left). It lists the rack or racks that are partly configured. If you want to
change or add to the configuration of one of these racks, move the cursor to the rack
name and press ENTER. The Rack menu (right) will appear. In this example, only
one rack has been previously configured.
Select Configure Rack and the Configure Rack menu appears.
Now select the type of information you want to supply. We’ll cover a typical cat-
RS.8D.M1.22 AK2-SC 255 Reference Manual 1 3
Starting with a
Completely
Un-configured
AK2-SC 255
egory right after we talk briefly about the other “route” configuration may take.
If the AK2-SC 255 you are working with has no refrigeration configuration at all,
select Refrigeration from the Main menu, and the Rack Configuration menu will
appear (left). The only selection which can be made from this screen is Add Rack.
Selecting Add Rack takes you to the Configure Rack, Rack Info screen (right).
Navigation and
making changes The Configure Rack A screen shown at right above has information fields that can be
changed by any user with a proper authorization code. To make changes, use the
arrow keys to move the cursor to the field you want to change
Entering numerals To enter numerals for a field like No of suction groups, use the numeral keys on the
controller keypad., then press ENTER.
Entering labels Labels are entries that you need to spell out. The Rack label field contains a label
one character in length. The Oil type field is also a label field, but it is 9 characters
long, allowing you to spell out a word or words indicating the oil type, for example,
“Mineral.”
To enter a label, place the cursor on the field, then press the +/- key. This action
toggles the function of the arrow keys so that the UP and DOWN arrows scroll
through the alphabet and all the other possible characters. Once the character you
want in that space appears, use the RIGHT arrow to move to the next space (when
the field has more than one space). Again, use the UP and DOWN arrows to reach
the character you want. When all the characters in the field are as you want them,
press ENTER to save the entry.
Constrained fields The Rack label field is a constrained field. It will only accept an upper case letter,
even though lower case letters appear as you scroll through the characters. The No
of suction groups field is also constrained. It will only accept a single numeric
character from 0 to 5, because a single AK2-SC 255 can control up to 5 suction
14 AK2-SC 255 Reference Manual RS.8D.M1.22
Selecting from list boxes
groups. Note that in the case of this particular field, entering a 0 (zero) will pop up a
warning box letting you know that a zero response here will eliminate the suction
groups already configured and will delete all information stored for the rack; you will
be asked to confirm the entry.
The next pair of illustrations shows how the controller uses list boxes.
The list box appears, as shown at left above, when you move the cursor to the field
and then press the +/- key (or, at your PC, right click). Then, using the UP and
DOWN arrow keys, you can move the cursor to make a selection. In the example at
right, R404A has been chosen. The cursor actually stayed in the same position, but
the “window” moved.
When you have put the list box’s cursor on the selection you want, press ENTER to
save your selection.
Some list boxes contain only two choices (for example, Yes and No in the Monitor
phase loss field). Some may contain many choices. When that is the case, one of the
lines in the box will contain three dots. When the cursor is moved to the three dots,
additional choices appear.
Now that we understand navigation and making changes, we can go on to a discussion of each of the configuration screens.
Configuring Rack Info In the rack Info screens, the following are the fields, and their possible contents:
Rack label (Upper case letters, A to Z) The “name” of the rack.
2 stage system (List box: Yes, No)
No of suction groups (0 to 5) Note that for a rack with existing configura-
tion, entering and confirming a 0 will cause deletion of
all existing rack information.
Refrig type (List box) The kind of refrigerant.
Oil type (9 characters, not constrained)
Monitor phase loss (List box: Yes, No) Whether or not there will be a
RS.8D.M1.22 AK2-SC 255 Reference Manual 1 5
digital input from a phase loss monitor.
Generate input for each [appears only after a Yes answer to the preceding
question] (List box) Whether there is a phase loss
input for each rack or each suction group.
Shutdown phase loss [appears only after a Yes answer to the Monitor phase
loss question] (List box: Yes, No)
When all of the items on the Rack Info screen have been configured, press MENU to
return to the Main Menu.
Adding a Rack There is only one way to add a rack. From the Main Menu select Configuration,
then Refrigeration, and the Rack Configuration screen appears. At the bottom left of
the screen are the words >> Add Rack<<. Move the cursor there and press
ENTER. A new Rack Info screen will appear.
Notice that the Rack Label field contains the letter B by default, since the previously
configured rack was rack A. You can change the default label if you want.
Configuring
Suction Info T o configure a suction group, press MENU to return to the Main Menu, then select
Configuration, then Refrigeration. The Rack Configuration screen appears as at
left above. Select the rack and a Configure Rack menu appears (as at left below) .
16 AK2-SC 255 Reference Manual RS.8D.M1.22
Once at suction configuration menu shown at right above, select the suction group you
want to configure and press ENTER. The Suction Info screen for that group will
appear as at right below. As you configure, questions may appear that are not
included on the default screen. The screen at left below shows all the possible lines
revealed.
The fields and their contents are as follows:
Suction I.D. (2 label fields: the first is a list box: A to Z; the second
PSIG target (-50.0 to 500.0) The pressure that the controller will
RS.8D.M1.22 AK2-SC 255 Reference Manual 1 7
is 9 characters not constrained) This is the identification you wish to assign to the suction group. The entry
will modify the screen title. For example, if you enter a
B in the first field and Low Temp in the second, the
right portion of the screen title for the configuration
and status screens for this group will read Low Temp
AB.
maintain, subject to capabilities of mechanical equip-
ment, for this suction group.
PSIG Safety cutout (-50.0 to 150.0) The gauge pressure at which the
controller will stop the compressors in this suction
group.
Adaptive suction control (List box)
None: No adaptive suction control.
AK2-SC 255: Target pressure is adjusted based on
discharge temperature of a single fixture.
AKC 16x: Adaptive control of individual evaporators
by an AKC 164 or AKC 161 Smart Case Controller.
Sensor: Target pressure is adjusted based on any
sensor on the AKC 55 I/O network
Dynamic: The SC 255 analyzes the performance of
every case on each individual circuit, and adjusts target
pressure intelligently by using the case sensor that
varies most from the setpoint.
Bd-Pt (For the first group, to the left of the hyphen, 01 to 99;
for the second group, to the right of the hyphen, 1 to 8).
The board and point address of the fixture sensor used
by the adaptive control algorithm. (Does not appear
when dynamic adaptive control is selected.) Note that
board and point numbers use a different format with
AK2 modules. See the AK2 I/O user manual for more
information.
Temp target (-50.0 to 100.0) The temperature that the adaptive
control algorithm will seek to maintain in the fixture.
(Does not appear when dynamic adaptive control is
selected.)
Range +/- (0.0 to 100.0) The dead band around the temperature
target. As long as the fixture temperature remains in
this range, the suction pressure target will not be
modified. (Does not appear when dynamic adaptive
control is selected.)
Maximum pressure float (0 to 99.9) The number of psig that the adaptive
algorithm will be allowed to cumulatively add or
subtract from the suction pressure target.
Post defrost delay (0 to 60) The number of minutes after termination of
defrost during which there will be no target adjustment.
(Does not appear when Sensor is selected as the type
of adaptive control.)
Allow float below target (List box: Yes, No) Determines whether or not the
adaptive algorithm will be allowed to adjust suction
pressure below the target if fixture temperature is
above target temperature + range.
Night setback (List box: Yes, No) Determines whether or not suction
pressure will be offset according to a schedule to be
specified in the following lines.
Setback from time (Time field) The start time for night setback.
Setback to time (Time field) The ending time for night setback.
Setback days (Days selection field) The days on which night setback
will be effective.
18 AK2-SC 255 Reference Manual RS.8D.M1.22
Setback holidays (Holidays selection field) The holiday numbers on
which night setback will occur. Holiday numbers are
defined in Store Info configuration.
At the bottom right of the Suction Info screen are the words “PG DN” for more.
Use the controller’s PG DN key to reach the next screen; shown at left is the default
screen in which not all the questions and fields appear; the screen on the right shows
all the fields.
Configuring
two-stage systems
The fields and their contents are as follows:
Monitor suction temp (List box: Yes, No)
Display superheat temp (List box: Y es, No)
Monitor desuperheat temp (List box: Yes, No)
Close EEV valves during
rack shutdown (List box: Yes, No)
If suct above target by (0 to 999.9) Number of psig above target when AKV
valves will be closed during rack shutdown.
Delay time (0 to 45) Number of seconds after suction pressure
reaches target + the number specified in the preceding
field that AKV valves will be closed.
Rack on AK2-SC 255 address
(0 to 15) The address of the SC 255 controlling the
rack that serves these EEVs.
Press EXIT to return to the Configure Rack Menu and continue refrigeration configuration.
and de-superheaters If (and only if) a rack is configured as a two-stage system, the
suction configuration for each suction group will include a special page for the low
side. The screen looks like this:
RS.8D.M1.22 AK2-SC 255 Reference Manual 1 9
The fields and their contents are as follows:
Is this 2-stage low side (List box: Yes, No) Is this the low side of the two?
Low side shutdown:
Shutdown on hi suct PSI (List box: Yes, No) Whether or not to shut down the
low side compressors when high side reaches a
specified suction pressure.
High side suct. PSI (-99.0 to 200.0) The high side suction pressure at
which the low side will be shut down.
Control desuperheater (List box: Yes, No) Whether or not de-superheater
control is implemented on this rack.
Controlling sensor (List box:)
Desuper In AA: Control is based on a sensor moni-
toring the liquid in temperature at the de-superheater.
Desuper Out AA: Control is based on a sensor
monitoring the liquid out temperature at the de-superheater.
Suction Temp AA: Control is based on a sensor
monitoring suction temperature.
Desuperheating temp (-50.0 to 200.0)
Range +/- (1.0 TO 10.0)
Configuring
compressors To begin configuring compressors, select Compressors from the Configure Rack
menu. The first page of the screen looks like this:
20 AK2-SC 255 Reference Manual RS.8D.M1.22
The fields and their contents are as follows:
No. of compressors (0 to 9)
Proof type (List box:) The means by which proof of compressor
operation is monitored.
None: No proof
OI: A digital input (on-of f input) is used for proof.
CT: A current transformer is used for proof.
Bitzer: Proof is obtained from a Bitzer electronic
module.
Reset Bitzer with RO (List box: Yes, No) Whether or not Bitzer compres-
sors are reset by a digital output (relay output).
Compressor size (1 to 500) The capacity of the compressor.
No. of unloaders (0 to 4) The number of compressor unloader stages.
Unloader capacity % (1 field per unloader: 0-99) The percent of capacity
shed by the respective unloader.
Inverter control (List box:) Type of variable speed control.
None: No inverter control
VO: An inverter is controlled by an analog output
(variable output).
VLT: A Danfoss VLT adjustable frequency drive is
used.
Inverter min. speed (1.0 to 150.0) The minimum percentage of rated
speed at which the inverter will run the compressor.
Inverter max speed (1.0 to 150.0) The maximum percentage of rated
speed at which the inverter will run the compressor.
RPM at max speed (1 to 9999) The RPM that will be displayed at maxi-
mum percentage.
Inverter max resets (0 to 10) The number of resets after which the
inverter will be put in override.
Inverter proof delay (0-99) The number of seconds without proof that must
elapse before an inverter reset occurs.
Min time between resets (0 to 99) The number of seconds that must elapse
before second and subsequent inverter resets.
RS.8D.M1.22 AK2-SC 255 Reference Manual 2 1
Configuring other
compressors in the
suction group Paging down, you will find a page for each compressor in the suction group. These
subsequent screens will have only questions pertaining to the individual compressors,
not the rack questions found at the top of the screen for compressor number one.
Compressor oil and
safety information After basic operating data has been entered for all compressors, paging down will
produce this screen:
The fields and their contents are as follows:
Oil control (List box: Yes, No) Whether or not oil control is
implemented.
Type of oil monitor (List box:)
Sensor Input: An analog input (sensor input) is used
to monitor oil pressure.
On/Off: A digital input (on-off input) is used to monitor
an oil pressure switch.
Copeland: A Copeland oil monitor is used.
Lockout comp on oil fail (List box: Yes, No) Whether or not compressors will
be locked out when an oil failure is detected.
Low oil pressure diff (0 to 50) The oil pressure differential, when an analog
sensor input is used, that will cause compressor
shutdown.
Oil pressure delay (0 to 255) When an analog sensor is used, the number
of seconds after oil failure is detected before compressors are reset.
No of oil reset attempts (0 to 10) After oil failure is detected, the number of
reset attempts before compressors are locked out.
Min time between resets (0 to 60) After a reset (whether successful or not) the
number of minutes that must elapse before another
reset attempt.
Monitor comp disch temp (List box: Yes, No) Whether or not compressor
discharge temperature is monitored.
22 AK2-SC 255 Reference Manual RS.8D.M1.22
Stop comps on high temp (List box: Yes, No) Whether or not compressors are to
be shut down on high discharge temperature.
Cutout (0.0 to 300.0) The discharge temperature at which
compressors are to be cut out.
Cutin (0.0 to 300.0) After a cut-out on high discharge
temperature, the discharge temperature at which
compressors are to be cut in.
Stop comps on low temp (List box: Yes, No) Whether or not comrpessors are to
be cut out on low discharge temperature.
Lockout (0 to 255) The number of minutes that must elapse
before a lockout on low discharge temperature. (See
note on next field).
below (0 to 300) The temperature that discharge must be
below for the time specified in the preceding field
before lockout on low discharge temperature occurs.
Note: If discharge temperature rises above the
setpoint, the time for lockout will restart from zero.
Disch pressure safety (List box: Yes, No) Whether or not comrpessors are to
be cut out on high discharge pressure.
Cutout (0.0 to 500.0) The discharge pressure at which com-
pressors are to be cut out.
Cutin (0.0 to 500.0) After a cut-out on high discharge
pressure, the discharge pressure at which compressors
are to be cut in.
Unload before cutout (List box: Yes, No) Whether or not comrpessors are to
be unloaded before being cut out.
Neutral Zone
control The next page of compressor configuration deals with neutral zone control. Basically,
neutral zone control acts to bring the current pressure toward target pressure more
quickly the greater the difference between the two. The screen looks like this:
The default settings are as shown in the screen above. It is recommended that the
values not be changed without a thorough understanding of the algorithm. A thorough
explanation of neutral zone control is available as an appendix to this manual.
RS.8D.M1.22 AK2-SC 255 Reference Manual 2 3
Compressor capacity
staging patterns Paging down from the neutral zone screen reveals the compressor staging pattern
screen:
In the default screen, the staging pattern is Auto, for automatic staging, and there is
no selection for Steps. The controller will stage rack capacity in the smallest steps
possible from lowest total capacity to highest, automatically selecting the compressors
combination to run for each stage (based on the the configured compressor capacities
available on the rack).
When there are a large number of steps, manual staging can be used to eliminate
needlessly small steps and compressor cycling.
T o use manual staging, select Manual from the pattern list box, then specify the
number of steps you want. The display that results will show a row compressor icons
for each stage. A compressor’s unloaders are represented by the small rectangles to
the right of the compressor icon.
In the sample screen, compressors are all 20 HP and each has 2 unloaders. Each
unloader is 33% of compressor capacity. These settings were determined on the
configuration page for each compressor.
Stage #1 is fixed at zero capacity and cannot be changed.
To change stage #2 or any higher stage, move the cursor to a compressor icon and
press enter. You will notice that the “piston” in the icon moves. When it is up, the
compressor is on. If there are unloaders on a compressor, subsequent clicks on the
compressor icon will turn the unloader steps on, one at a time. The small rectangles
will change color to indicate that the step is on. When all steps are on for a compressor, the next click on the icon will turn everything off.
As you change a stage’s capacity, the number in the right column of the screen will
24 AK2-SC 255 Reference Manual RS.8D.M1.22
change for that stage, giving the total horsepower you have selected for that stage.
You can change the number of steps at any time.
Configuring
evaporators To begin configuration of evaporators, return to the Configure Rack menu and select
Evaporators. Or, from the Main Menu (which you can always reach with the
MENU key) select Configuration, Refrigeration, the particular rack, and Evaporators.
The evaporator menu will initially look like as on the left below , with no evaporators
listed, but as soon as you enter a number in answer to the top question, and select
from the Type list box for some of the evaporators, the screen will look something
like the one at right:
There are six kinds of evaporator control shown. In this manual, we will discuss the
configuration of SC 255 circuits and AKC 16x circuits. For the other types of evaporators, please see the manuals on the individual controllers. In the future, when a
Danfoss Case Control manual is created, we will remove the AKC 16x material from
this manual.
First, the changeable fields in the Evaporator Menu (shown above on the right) are as
follows:
Number of circuits (1 to 40) The number of circuits in the suction group.
Dewpoint method (List box:)
Dewpoint: A dewpoint sensor or sensors will be used
for anti-sweat control.
Calc Dewpoint: Dewpoint for anti-sweat control will
be calculated using the values of relative humidity and
temperature sensors.
Dewpoint sensor to use [If Dewpoint has been selected](List box:) How anti-
sweat control dewpoint will be determined if a
dewpoint sensor is used.
Min Dewpoint: The lowest-reading of a number of
dewpoint sensors will be used.
Max Dewpoint: The highest-reading of a number of
RS.8D.M1.22 AK2-SC 255 Reference Manual 2 5
dewpoint sensors will be used.
Average: The average of a number of dewpoint
sensors will be used.
Dewpoint 1: A single dewpoint sensor will be used for
control.
[others]: Other dewpoint sensors, if they exist, will be
listed also.
Humidity sensor to use: [If Calc Dewpoint has been selected](List box:) How
dewpoint will be determined if a humidity sensor is
used.
Min Humidity: The lowest-reading of a number of
humidity sensors will be used.
Max Humidity: The highest-reading of a number of
humidity sensors will be used.
Average: The average of a number of humidity
sensors will be used.
Inside RH 1: A single humidity sensor will be used
for control.
[others]: Other humidity sensors, if they exist, will be
listed also.
Auto defrost schedules (List box: Disabled, Enabled)
Enabling this option will cause the controller to suggest
a defrost schedule based on the following two additional questions.
Maximum concurrent electric defrosts
[Appears only if Auto defrost schedules is enabled]
(0 to 20) The number of electric defrosts that can be
underway concurrently .
Include dripdown time [Appears only if Auto defrost schedules is enabled]
(List box: Yes, No) Answering “Yes” will cause a drip
down period to follow defrost before refrigeration is
allowed. The length of the drip down period will be that
specified by the user when defrost schedules are autoconfigured.
Type (List box:) [for each individual evaporator] the type of
evaporator control.
AK2-SC 255/SUBC: A subcooler controlled as an
SC 255 circuit.
AK2-SC 255: The circuit is controlled by the SC
255’s algorithms.
AKC 16x: Control is at the fixture by AKC 161 or
AKC 164 Smart Case Controllers.
EKC: Control is at the fixture by EKC 201 controllers.
Deg Master: Control is at the fixture by Hill/PHOENIX Degree Master controllers.
DCU: Control is at the fixture by DCU case controllers.
Case lights button In the lower left corner of the screen body is a button, CASE LIGHTS. Selecting this
button and pressing ENTER will open the configuration screen for a case lights
26 AK2-SC 255 Reference Manual RS.8D.M1.22
override switch. The screen at left below appears (with the list box closed) when the
CASE LIGHTS button is activated. The fields on the screen and their meanings are
as follows:
Type of override switch (List box)
Disabled: There is no override switch configured.
On/Off: A two-position override switch allows the
lights to be switched on or off.
On/Auto: Choices are ON or automatic operation.
Off/Auto: Choices are OFF or automatic operation.
On/Auto/Off: All three choices are available with a
three position switch being installed.
Depending upon configuration and the equipment
present, dewpoint for anti-sweat control can be read
from a dewpoint sensor, or it can be calculated using
the values of relative humidity and temperature sen-
sors.
Configuring AK2-SC 255
subcooling circuits When subcooler valves are controlled directly by the SC 255 (that is, when an AKC
RS.8D.M1.22 AK2-SC 255 Reference Manual 2 7
165 Subcooling Controller is not used) configuration begins by selecting AK2-SC 255/
SUBC in the Type column for the circuit on the Evaporator Menu, then moving the
cursor to the word Setup for that evaporator and pressing ENTER. A screen like the
one at left below will appear. The same screen with all its fields revealed appears as
at right.
The fields are as follows:
Number of valves (0 to 2) The number of valves used for subcooling.
Number of stages (1 to 3) With one valve, there can be only 1 stage of
subcooling. W ith two valves, there can be two stages
(one valve open or two). If there are two valves
feeding subcoolers of different capacities, then there
can be three stages (only valve 1 open, only valve 2
open, or both valves open).
Cutin setpoint (0.0 to 120.0, each stage has a separate setpoint) The
temperature at which the subcooling stage will become
active. Temperature is measured by a sensor at the
liquid outlet of the subcooler.
Cutout setpoint: (0.0 to 110.0, each stage has a separate setpoint) The
temperature at which the subcooling stage will shut
down.
Minimum ON time (0 to 255) The minimum time in minutes each stage
must remain active after being cut in.
Minimum OFF time (0 to 255) The minimum time in minutes each stage
must remain off after being cut out.
Configuring
AK2-SC 255
refrigeration circuits If there is not a distributed controller at the fixture (AKC 161, AKC 164, Degree
Master, or DCU), refrigeration can be controlled directly by the AK2-SC 255. Configuration of such circuits starts by selecting AK2-SC 255 in the Type column for the
circuit on the Evaporator menu, then moving the cursor to the word Setup for that
evaporator and pressing ENTER. A screen like the one at left below will appear. The
28 AK2-SC 255 Reference Manual RS.8D.M1.22
same screen with all its fields revealed appears as at right.
The fields are as follows:
Fixture Type (List box) Various types of fixture can be selected:
box, multi-deck, single deck, service, etc.
Fixture Name (List box) There is a large selection of common fixture
names for each of the fixture types that can be selected above, and there is a selection User Def. After
making that selection, you will be able to spell out your
own name on the following line.
Enter user defined name (Label) The name of a user-defined fixture. Any of
the characters in the AK2-SC 255 character set can be
used, including upper and lower case letters and
symbols.
Monitor box door (List box: Yes, No) Whether or not a box door switch
will be monitored (appears for boxes only).
Shutdown when door open (List box: Yes, No) Whether or not to shut down
refrigeration when the box door is open.
No case/box sensors (0 to 15) The number of sensors in this fixture or
circuit.
Temperature control (List box: Yes, No) Whether or not temperature contol
will be used.
Controlling sensor (List box:)
Min Temp The lowest of the sensors in the fixture or
on the circuit will be used for temperature control.
Max Temp The highest of the sensors in the fixture
or on the circuit will be used for temperature control.
Average The average of all the sensors in the fixture
or on the circuit will be used for temperature control.
[circuit names] The name of each sensor will be
listed, and any can be selected. That sensor , then, will
be used for temperature control.
Target: (-99.0 to 150.0 [target] 1.0 to 20.0 [range] The target
RS.8D.M1.22 AK2-SC 255 Reference Manual 2 9
Loading...