AKCESS System Manual RC.IU.B1.22 4/99.1 1-1
Chapter 1 Introduction
In the design and production of a new generation of control and monitoring systems for supermar-
kets, Danfoss listened to a wide variety of users, including equipment manufacturers, installers,
facility managers, and service personnel. The result of extensive user involvement during continuing
development, the Danfoss AKCESS system makes tomorrow’s supermarket control a present-day
fact, and makes it easy, too.
The fundamental building block of the AKCESS system is the Danfoss AKC 55 Controller. It is
easy-to-configure and easy-to-use, and has features to answer every user’s needs.
The AKC 55 has a keypad and a graphic display, and features icon-driven software. The AKC 55
is completely user-configurable, with no need for a separate “database” file of equipment and
control parameters.
The illustration above shows the basic AKCESS AKC 55 System components, except for sensors. We’ll
first discuss system capacities, then introduce each component in detail.
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System Capacities
An AKCESS system can have up to 15 AKC 55’s making up a Host Network. Each AKC 55 can have
up to 95 I/O network nodes. Nodes can be:
RO8 Relay Output boards (8 relay outputs each)
VO2 Variable Output boards (2 variable outputs each)
OI8 On/Off Input boards (8 on/off inputs each)
SI8 Sensor Input boards (8 sensor inputs each)
Smart Case Controllers for liquid side or suction side control (each controls refrigeration, lights,
fans, defrost, and anti-sweat heaters for a single refrigerated fixture)
RTC Rooftop Control boards (each controls functions for a single RTU)
Device capacities for an AKCESS network are as follows:
Refrigeration ü 5 Suction Groups
ü 8 Compressors per suction group
ü 4 Unloaders per compressor
ü 1 variable speed motor control per suction group
ü 40 Circuits per suction group
ü 2 Heat reclaim stages per suction group
ü 5 Subcooling circuits
ü 5 Condensers (air cooled or evaporative)
ü 12 Fans per condenser (air cooled)
ü Variable speed condenser control
HVAC Up to 32 Systems (AHU, RTU, RTC, and Seasons4 Smart Coil units)
AHU’s & RTU’s ü Direct control using RO, VO, SI, and OI boards
ü 2-speed fan control (plus variable speed on AHU’s)
ü 6 Cooling stages per air handler
ü 5 Heating stages per air handler
ü 2 Heat reclaim stages
ü Analog gas valve control
ü 5 Dehumidification stages, including dessicant systems
ü Damper control
ü Multiple compressor control
ü Compressor and condenser control
Alternative RTU control ü Control via Rooftop Control (RTC) Board (has standalone capability)
ü 1 Fan stage
ü 3 Heating stages
ü 3 Cooling stages
ü 1 Damper or economizer
Lighting ü 30 Lighting zones
ü 6 relays per zone
ü Standard or relative schedules
ü Up to 8 schedules per zone
ü Automatic override for burglar or fire alarm
ü Switch override with OVR Override Box
Miscellaneous Points ü 20 Logic statements per AKC 55
ü 5 relays per statement
ü 20 Miscellaneous sensor inputs and on/off inputs
for monitoring and alarming
Switch Override Boxes ü 1 Box per AKC 55, 8 switch overrides per box
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Non-AKCESS Nodes ü 5 EMON energy meters per AKC 55
ü 8 Bitzer (Echelon) compressor interfaces per suction group
ü 5 Square D Powerlink
®
(Echelon) panels per AKC 55 (42 breakers each)
ü 1 Danfoss VLT (Echelon) variable frequency AC drive per compressor, 1
per condenser group, and 1 per AHU
Demand Limitiing ü Using 1 of the EMON energy meters per AKC 55
Alarms ü Configurable for all inputs and outputs, plus system alarms
ü Delivered by modem, ethernet , and local printer
Office Alarm Boxes ü Up to 3 OAB-1’s per AKCESS system
History ü Up to 600 datapoints per AKC 55
Communications ü Local via RS 232
ü Modem using standard telephone line
ü Ethernet
Security ü 5 Authorization levels
ü 5 Account codes per level
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AKA 65 Danfoss AKA 65 AKCESS Network Supervisor
software is a system option which runs on any
PC with Windows for direct RS 232, modem , or
ethernet communication with any AKC 55 system.
It shows precisely the same screens, navigational
icons, and information that appear on the AKC
55’s LCD display, and for properly authorized
users, allows changes to AKCESS system
settings, collection of history, and
troubleshooting of an entire control system from a
single location.
A PC running AKA 65 Network Supervisor can be added to any AKCESS AKC 55 network. In
addition, Network Supervisor is used on remote PC’s to communicate with one or any number of
AKCESS AKC 55 networks by modem over standard dial-up telephone lines or ethernet networks.
Linking your PC to the AKCESS host network and using AKA 65 Network Supervisor software are
covered in Chapter 7.
AKC 55 An AKC 55 controller has two components: (1) a main CPU (central processing unit) board; and (2) a
PS/COMM (power supply and communications) board. Up to 15 AKC 55’s connected by and
communicating over an RS 485 bus make up an AKCESS system’s host network.
History History is collected and stored in the standard system and in optional memory modules of various
capacities.
Communications
Modem Optionally, a modem can be installed in any of the AKC 55’s in a network for remote communications
over a standard voice-grade dial-up telephone line.
Ethernet An AKCESS network can have one or two ethernet network connections.
Nodes Each AKC 55 can have up to 95 nodes in its I/O network, but there is a maximum of 99 nodes of each
type, since each board must have a two-digit address between 01 and 99. Nodes are principally input-
output boards and Danfoss Smart Case Controllers. TP-78K twisted pair cable (with shield) is used for
connecting the I/O network, both between nodes and to the host AKC 55.
Inputs and
Outputs Each AKC 55, with appropriate I/O nodes, can have up to: 256 relay outputs; 256 on-off inputs; 225
sensor inputs; and 225 variable outputs, using the boards described in the following Chapter.
Echelon
Interface Although the AKCESS system uses TPT Transceivers, a TPT-FTT bridge makes possible
interface to Echelon devices which use Free Topology Transceivers.
System Components
akc55box.dwg 2/99
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Input and Output Boards
RO8
Relay Output
Board The RO8 provides eight relay outputs using class C relays, each with normally open, normally closed,
and common connections for general purpose control applications. RO8 relay outputs are fused at 5
amps. For each output relay, there is an LED which lights when the relay coil is energized.
RO8S
Relay Output Board
with Override Switches
The RO8S is electrically identical to the RO8 board just described, except that it is provided with a
three-position override switch for each output. The output is in automatic mode, controlled by the
AKC 55, when the switch is in the middle position. The relays can be overridden either to a coil-
energized state or to a coil-de-energized state.
OI8 & OIL8
On-off Input
Boards The OI8 provides eight general purpose on-off inputs (48-240 VAC) for device monitoring. The OIL8
provides low voltage inputs (9-80 VAC). Inputs are optically isolated and fused at 0.5 amp. Each
input has an LED which lights when input voltage is sensed.
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SI8
Sensor Input
Board The SI8 provides eight analog inputs (default range 0-6 VDC) for Danfoss sensors for temperature,
pressure, light level, and other analog measurements. Sensors from other manufacturers may be
compatible if they have an output range of 1-2, 0-5, or 1-6 VDC (you can select the range during
configuration). Readings from non-Danfoss sensors will be meaningful if they have one of the appropri-
ate output voltage ranges and a linear response. It is best to consult with your Danfoss representative
before using non-Danfoss sensors.
VO2
Variable Output
Board
The VO2 provides two analog outputs (0-10 VDC) for general purpose control of devices such as
variable speed compressors and motors, analog gas valves, and linear damper motors. The output can be
limited to a range of 0-5 VDC through software.
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Dual I/O Boards RO8 Relay Output boards and OI8 On/Off Input Boards are available as dual boards. All
specifications including power requirements remain the same as for two individual boards. The
illustration shows an RO8D dual Relay Output Board.
OVR Override Box
Occasionally store personnel come in early, stay late, or
otherwise need light or seasonal HVAC at times when the
devices are normally scheduled off. The OVR allows them to
turn on lights at these times for a pre-determined period.
Each OVR has eight switches. Each switch is assigned to a
lighting zone or HVAC device for which override capability is
desired. During lighting and HVAC configuration, each is
assigned an override time in hours and minutes (up to 23
hours 59 minutes).
One or more OVR’s can be used depending on how many
zones or HVAC devices need to have override capability.
Each OVR
Override Box counts as one node in the 95 node capacity of
the I/O etwork.
OAB-1 Office Alarm Box
When an Office Alarm Box is connected to your AKCESS
system, audible and visual notification of an alarm situation
can be received locally.
When an alarm is generated, a small red LED on the OAB
lights and an intermittent beeper sounds. The sound can be
turned off with the “Silence” switch, but the red light will
remain on as long as the alarm condition exists.
The OAB is NOT one of the nodes on the I/O network;
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it is connected to a relay output.
Smart Case Controllers
In Smart Case Control, all fixture functions (refrigeration, defrost, fans, anti-sweat heaters, and lights) are
regulated by a single Danfoss AKC 164SC controller located in the fixture itself. The Smart Case
strategy allows each evaporator and associated functions in the same fixture to be individually controlled,
independent of other fixtures in the line up. Danfoss Smart Case Controllers, valves, and sensors are
pictured below.
There are various benefits to the Smart Case Strategy, including more appropriate and constant product
environment; installation savings on materials and labor; energy savings; remote monitoring and alarming
capability; and diagnostic and service benefits.
As appropriate for the type of fixture, Danfoss Smart Case Control can be liquid side control using a
Danfoss AKV electronic expansion valve or suction side control using a Danfoss KVQ electronic
evaporator pressure regulating valve with thermostatic expansion valves.
Liquid Side
Control Liquid side control is achieved with an AKC 164 Smart Case Controller and an AKV 10 or AKV 15
electronic expansion valve. An AKV valve regulates liquid supply to the evaporator so that injection is
optimum under all operating conditions. Liquid injection is governed by an adaptive software algorithm
in which the difference between the evaporator’s inlet and outlet temperatures is compared with a
reference superheat. The optimal superheat varies with changes in operating conditions, so the Smart
Case Controller varies the reference superheat according to those same conditions.
Minimum and maximum reference superheat are factory set. The range limits normally do not need to
be changed. Superheat adjustment by the controller is completely automatic.
AKV 10 and AKV 15
Electronic Expansion Valves
The AKV is a solenoid valve with a built-in expansion orifice and
a dampening device. Dampening increases the valve’s longevity; the
AKV’s tested lifetime is in excess of fifty million cycles. The AKV 10
does not modulate, but is fully opened when refrigeration is called
for. Thus refrigerant always enters the coil at full velocity, improving oil
return.
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AKV 10 and AKV 15
Pulse Width
Modulation AKV valves operate on the principle of pulse-width modulation. The valve is cycled in six second
periods. During operation, the valve opens for some percentage of each period (from 0%, when there is
no need for refrigeration, and the valve remains closed for the entire six seconds, to nearly 100%, when
full refrigeration capacity is required). The percentage of the period for which the valve is open is based
on changes in load as determined by measured variations in superheat.
Temperature
Control With liquid side Smart Case Control, you can use the standard target with +/- range temperature strategy
or, where extremely tight fixture temperature control is critical (for example, in meat and fresh fish cases)
you can order the modulated temperature control option for your Smart Case Controllers. Modulated
temperature control is a unique approach which allows regulation as close as ±½
o
F.
Suction Side Control Where suction side control is desired, as it may be in service meat
cases or when there are multiple evaporators in a single fixture, an
AKC 164 Smart Case Controller controls a Danfoss KVQ electronic
EPR valve on the suction side. Thermostatic expansion valves are
used on the liquid side of the evaporator.
KVQ Electronic
EPR Valve The Danfoss KVQ is an electronic evaporator pressure regulating valve which operates on a heat motor
principle, and is available with or without a right-angle copper outlet extension. The complete assembly
consists of a valve body and actuator.
Defrost Control Standard Smart Case Control defrost strategy includes time-initiated defrost with termination by time or
by temperature with time-duration fail-safe. Where defrosts for multiple evaporators in the same line-up
are scheduled at the same time, and where there are no dividers between the fixtures, the Coordinated
Defrost Function can be used to insure that there is no conflict between refrigeration and defrost. In
other words, Smart Case Controllers operating under Coordinated Defrost on the same schedule all
return to refrigeration at the same time.
Intelligent
Defrost Intelligent Defrost is an optional new strategy developed by Danfoss for use with its AKV valves. With
Intelligent Defrost, no additional hardware is required. If a scheduled defrost is determined to be
unnecessary, that defrost is skipped. Contact Danfoss for application information and availability.
AKS 16
Drain Sensor When fixtures are equipped with Danfoss AKS 16 Drain Sensors, Smart Case Controllers will give early
warning at the first signs of a plugged drain.
Fan Control Fans can be programmed to stop during defrost and to delay re-starting after defrost termination.
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Anti-Sweat
Heater Control Control of anti-sweat heaters is based on dewpoint. High and low dewpoint limits are selected. Above
the high limit, anti-sweat heaters are on continuously; at and below the low limit, they are kept off.
Between the limits, the heaters are turned on for a part of each time cycle. The actual time the heaters
are on is dependent upon how close the dewpoint is to the upper or lower limit. You select the length of
the time cycle and the upper and lower limits during configuration.
A high temperature safety cut-out can be set up so that when a user-specified high temperature is
sensed, the anti-sweats will be shut down and prevented from operating until fixture temperature is once
again safe.
Lighting Control An AKC 164 controls fixture lights based on schedules you create during configuration. Lights can be
configured to be off during defrost if necessary.
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