EC2-552_65098_EN_R05.docxx replacement for R04 1 / 4 PCN: 864923 30.07.2012
EC2-552 Condensing Unit Controller
Operating Instructions
GB
Note: This document contains short form instructions for experienced users.
Use last column in List of Parameters to document your individual settlings.
More detailed information can be found in the User Manual.
The EC2-552 has been designed to control single compressor or tandem
compressor condensing units with a Copeland Scroll Digital
TM
compressor and
variable fan speed control. The purpose of the controller is to maintain suction
pressure at a pre-defined level by modulating compressors and to keep condensing
pressure to a minimum by varying fan motor speed.
The Alco Controls PT5 pressure transmitter (1) senses suction pressure. The
Digital Scroll Compressor (6) operates as the base load compressor. Capacity
modulation is achieved by temporarily unloading the compressors scroll sets with
the Pulse Width Modulated (PWM) signal (11) which controls the compressor
unloading valve (12). In tandem compressor condensing units, the single stage
compressor (7) will only be turned on when demand exceeds the refrigeration
capacity of the Digital Scroll Compressor. The discharge temperature thermistor of
the Digital Scroll Compressor should be connected to the Disch. Temp. input (5) of
the controller and the volt-free digital inputs (3) and (4) should be connected to the
serial alarm loops of both compressors for feedback of compressor tripping.
setpoint pressure
2 control loops with the same suction pressure setpoint P0 modulate the
compressors. The dead band control loop with dead band P1 switches the single
stage compressor on or off, whereas a PI control loop modulates the Digital Scroll
base load compressor between approximately 10% and 100% capacity. Being the
base load compressor, the Digital Scroll Compressor will never be switched off
while the single stage compressor remains on.
The PT5 pressure transmitter (2) senses condensing pressure and feeds the signal
into a control loop which generates a 0…10V output signal (10) to modulate
condenser fan motor speed by using the Alco Controls FSP Fan Speed Power
Module. The control algorithm for condensing pressure is generating a proportional
transfer characteristic:
pressure
P0 is the condensing pressure setpoint for the fan. P1 is the proportional pressure
band within the fan speed is controlled proportional.
!
Safety instructions:
•
Read installation instructions thoroughly. Failure to comply can result in
device failure, system damage or personal injury.
•
The product is intended for use by persons having the appropriate
knowledge and skills.
•
Ensure electrical ratings per technical data are not exceeded.
•
Disconnect all voltages from system before installation.
•
Keep temperatures within nominal limits.
•
Comply with local electrical regulations when wiring
Technical data:
Power supply 24VAC ±10%; 50/60 Hz; Class II
Power consumption 20VA max.
Communication TCP/IP Ethernet 10MBit/s
Plug-in connector size Removable screw terminals
wire size 0.14 … 1.5 mm
2
Temperature
storage
operating
-20 … +65°C
0 … +60°C
Humidity 0 … 80% rh. non condensing
Protection class IP65 (front protection with gasket)
Pressure transmitter inputs
24VDC, 4…20mA
Digital inputs Volt free contacts 5V/0,1mA
Variable fan speed output 0…10V, 3mA max
Triac output 24VAC 0,1…1A
Output relays SPDT contacts, AgCdO
Inductive (AC15) 250V/2A
Resistive (AC1) 250V/8A; 12A total return current
Marking
Mounting
The EC2-
552 can be mounted in panels with a 71 x
29 mm cutout. See dimensional drawing below for
space requirements including rear connectors.
Push controller into panel cutout.(1)
Make sure that mounting clamps are flush with
outside of controller housing
Insert allen key into front panel holes and turn
clockwise. Mounting clamp will turn and gradually
Turn allen key until mounting clamp barely touches
panel. Then move other mounting clamp to the same
position (3)
Tighten both sides
very carefully until controller is
secured. Do not over tighten as mounting clamps
Refer to the electrical wiring diagram
(right) for electrical connections. A copy of
this diagram is labelled on the controller.
Use connection wires/cables suitable for
90°C operation (EN 60730-1)
EC2 analog inputs are for dedicated
to any other devices. Volt free digital
inputs should only be connected to serial
control loops or relays with gold contacts.
They should not be connected to any other devices
Important: Keep controller and sensor wiring well separated from mains wiring.
Minimum recommended distance 30mm.
Warning: Use a class II category transformer for 24VAC power supply (EN
60742). Do not ground the 24VAC lines. We recommend to use one transformer
per EC2 controller and to use separate transformers for 3
rd
party controllers, to
avoid possible interference or grounding problems in the power supply. Connecting
any EC2 inputs to mains voltage will permanently damage the EC2.
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