Alco Controls

Electronic Superheat Controllers and Stepper Motor Drivers
A2.5.1/1003/E
ALCO designed superheat controllers and valve
drivers for stepper motor driven control valves for
all commercial refrigeration and air-conditioning
applications.
EC3-X33 is a universal superheat controller without
network communication for air conditioning,
refrigeration and industrial applications such as
chillers, industrial process cooling, rooftops, heat
pumps, package unit, close control, cold room, food
process and air driers. The ECD-002 Display/keypad
Unit is necessary for setup but not for operation
of the controllers. ECD-002 can be connected or
disconnected to EC3-X33 at any time.
In the event of a cooling request and compressor
start-up, EC3-X33 needs to be informed. This can
be achieved by a digital input. EC3-X33 will start
to control the refrigerant mass flow stand-alone
by precise positioning of the Control Valve under
different operating conditions such as compressor
start-up, start of a further compressor, high head
pressure, low head pressure, high load, low load
and partial load operation. EC3-X33 is capable for
diagnostics and alarm. The alarm can be received
via relay output as well as optical LED/alarm code
on ECD-002.
The EC3-X32 has a similar function as EC3-X33 but
with a TCP/IP Ethernet communication interface
enabling the controller to be directly connected to
a network or a PC via the standard Ethernet port.
The EC3-X32 controller has embedded WebPages to
Display Case and Coldroom Controllers
The compact EC2 series is available with either TCP/IP
or LON communication protocols and covers also
applications where the display cases are connected
to a multiple compressor application. In this case,
the dedicated compressor relay on the controller is
no longer required and is available as a spare relay to
perhaps switch the display case lighting.
The controllers can therefore be split into two groups;
controller is required to switch the compressor
directly; integral application and those connected
to a multiple compressor (rack) system.
The EC2-21x, EC2-31x and EC2-35x have the
dedicated compressor relay
The EC2-29x, EC2-39x and EC2-37x are for use with
the rack system.
The EC2-200 series of controllers are specifically
designed for display cases for use with TXV. The
controller performs the function of thermostat,
defrost and fan management and is capable of
operating a standalone condensing unit or being
incorporated into a distributed system controlled
by a rack.
The EC2-300 series incorporate the functionality of
the EC2-200 model but additionally have a superheat
algorithm to control the EX2 control valve:
Alco Controls
enable the user to visualise the parameter list with a
standard WebBrowser like Internet Explorer®. When
connected to a suitable connection, the controller is
able to automatically send alarms by email to a PC
or mobile phone.
For use with Copeland Scroll Digital TM technology
two other models are available. EC3-D73 is a standalone
version for use with the ECD-002 Display /
Keypad unit whilst the EC3-D72 has a TCP/IP Ethernet
interface.
A 0-10V demand signal is required from a third
party controller to control a tandem system with
one fixed and one digital compressor. A patented
algorithm synchronises the operation of the PWM
digital compressor valve and the EX series electrical
control valve.
EXD-U Universal Drivers are stepper motor drivers
and enable the operation of ALCO stepper motor
driven valves EX4 ... EX8 as Electronic expansion
valve, Capacity control by means of hot gas bypass or
evaporating pressure regulator, Crankcase pressure
regulator, Condenser pressure regulator, Liquid level
and Liquid injection.
The universal driver module can be connected to
any controller which can provide a 4-20mA or 0-10V
analogue signal. The output is the opening/closing
of EX4 ... EX8 and consequently the control of the
refrigerant liquid or vapour mass flow in accordance
with the analogue input.
EC2-31x / EC2-39x (Temp / Temp): the superheat is
controlled using two temperature sensors.
EC2-35x / EC2-37x (Pressure / Temp): the superheat
is controlled using a pressure transmitter (PT5 series)
in conjunction with a temperature sensor.
Whilst the products were developed for display
cases, they may also be applied to control a simple
coldroom.
The EC3 series utilize in principle the same software
technology of the EC2 series but provide additional
inputs and outputs to satisfy the requirements of
even the most demanding systems. Like the EC2,
the EC3 series may be connected together to form
larger systems combining the control of multiple
compressors and fans. The optional ECD-001
Display/keypad Unit is available to display the
system temperatures, indicate system status and to
modify parameters.
The EC3-300 series are specifically for use with
stepper valve series (EX4, EX5, EX6, EX7, EX8). In case
of power loss the Electrical Control Valve needs to be
closed to avoid flooding of the compressor, therefore
each valve requires a battery backup. For this reason,
the battery together with its automatic charging
circuit has been incorporated into the controller
housing significantly saving installation time as well
as space in the electrical enclosure.
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