Alco Controls

Electronic Valve Drivers and Controllers
30
ALCO designed a large number of electronic
controllers for most requirements of commercial
refrigeration and air-conditioning applications. They
can be grouped into two groups:
The stand alone controllers typically reproduce
the function of a mechanical valve, like superheat-
or pressure control, but offering advantages of
application of electrical control valves.
The networked controllers normally combine more
functions (superheat control, temperature control,
alarming, defrost) with network capabilities.
EC3-X33 is a stand-alone universal superheat
controller 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 optional 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 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 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
enable the user to visualise the parameter lists using
real text labels.
To view WebPages on the PC, a standard WebBrowser
like Internet Explorer ® or Mozilla Firefox and JRE
Java Runtime Environment is needed. JRE can be
downloaded at no charge from the ALCO website.
A new range of EC3 series has been introduced
to enhance the superheat controller for use with
Copeland’s Digital Scroll technology. Two models
are available; the EC3-D73 is a stand-alone version
for use with the ECD-002 Display / Keypad unit
whilst the EC3-D72 has a TCP/IP Ethernet interface
enabling customers to visualise the parameters via
the built-in WebPages. When connected to a suitable
connection, the controller is able to automatically
send alarms by email to a PC or mobile phone.
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/EX5/EX6/EX7/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 driver module requires an analogue input with
4 to 20mA or 0 to 10V. The output is the opening/
closing of EX4/EX5/EX6/EX7/EX8 and consequently
the control of refrigerant liquid or vapour mass flow
in accordance with analogue input. The universal
driver module can be connected to any controller
which can provide a 4-20mA or 0-10V analogue
signal. This gives extreme flexibility to system
manufacturers to use any desired controller in
conjunction with universal driver module to achieve
different functionality.
Selection Table Superheat Controller and Universal Driver Module
Description TCP/IP Stand alone Page
Superheat Controller for stepper motor driven electrical control valves EC3-X32 EC3-X33 34
Digital Superheat Controller for Stepper motor driven electrical control valves EC3-D72 EC3-D73 34
Universal Driver Module - EXD-U00 35
A2.5.1/0706/E