SRW EWPX 173 Quick Start Manual

WHAT IT IS
EWPX 173 is a digital microproces-
sor based device designed to con-
trol refrigerating units; it is
particularly suitable for applications
on "forced air" units operating at
low or normal temperature.
The instrument is provided with
three low voltage outputs to control
three auxiliary relays devoted to
users control: compressor, defrost
system and evaporator fans.
HOW IT IS MADE
• Housing: plastic resin PC+ABS ex-
tinguishing grade V0
• Size: front panel 76x34 mm, depth
58 mm
• Mount: panel mount on 71x29 mm
hole
• Protection: front IP65
• Connections: telephone connector
for the connection to the EWDR
SLAVE module
• Remote connection: serial con-
nection to the EWPX ECHO re-
peater
• Serial connection: TTL port for the
connection to the EWRS 485 inter-
face for TELEVIS system linking
• Commands: all located on front
panel
• Autonomy for real time clock data:
5 hours approx.
• Outputs: three 12 Vdc/40 mA out-
puts to control the auxiliary relays
in the EWDR SLAVE Din module
(compressor, defrost system and
fans)
• Analogue inputs: two NTC probe
for temperature control and de-
frost management in the EWDR
SLAVE Din module; 1 ON/OFF in-
put for a door switch
• Resolution: 1 °C
• Accuracy: better than 0.5% end of
scale
• Power supply: 12 Vca/cc or 230,
110, 24 Vca (supplied by the
EWDR SLAVE 173)
EWPX 173/S/E
controller for "forced air" refrigerating units with
EWPX ECHO and Televis system outputs
GENERAL DESCRIPTION
EWPX 173/S/E is a digital microprocessor
based device designed to control refriger-
ating units; it is particularly suitable for ap-
plications on "forced air" units operating at
low or normal temperature.
The instrument is provided with three low
voltage outputs to control three auxiliary
relays devoted to users control: compres-
sor, defrost system and evaporator fans.
Relays are installed in the EWDR SLAVE
Din module (version 173), which also pow-
ers the instrument. The module is con-
nected to the instrument through
MULTIPOLAR CABLE provided with po-
larised, disconnectable telephone connec-
tors at both ends.
The instrument provides two input probes
connected to the Din module for tempera-
ture control and defrost management.
The MULTIPOLAR CABLE conveys the in-
put signals from the NTC probes, the con-
trol signals for the module relays, and the
power supply voltage for EWPX 173/S/E.
EWPX 173/S/E) also includes a RS-485
port for the direct connection to the TELE-
VIS system and to the EWPX ECHO re-
peater, which allows remote display of the
temperature shown on the instrument.
All versions include an internal clock to
control defrosts and a led for alarm sig-
nalling. An internal back up device guaran-
tees time counting also in case of power
failure.
EWPX 173/S/E is available in the two key
front panel 32x74 (ELIWELL standard);
EWDR SLAVE (version 173) is supplied in
the 70x85 (4 modules) format for din rail
(Omega 3) or wall mount.
OPERATION
When operating in the field of refrigeration
the temperature control is performed with
a positive differential; the compressor
stops when the Setpoint temperature is
reached and restarts when the tempera-
ture reaches Setpoint plus the differential.
Two different defrost types can be select-
ed: electrical (the compressor is stopped)
or at cycle inversion (warm gas; the com-
pressor keeps working); it is also possible
to select the interval between defrosts
(and the interval count type; alternatively,
through the clock option up to six different
real times for defrost start can be set), the
stop temperature and a maximum time
(time-out) after which defrost is interrupt-
ed.
The same probe which controls the defrost
cycle is used to control the evaporator
rel. 6/97 ing
fans; it is possible to set the stop temper-
ature, the delay time after a defrost and the
relation of fans with the compressor and
the micro gate contact.
A series of "safety controls" (delay at start-
up, minimum disable time, minimum time
between activations) protects the com-
pressors from close starts.
In case of probe error or temperature
alarm the instrument signals the event
through the alarm led on the front panel.
The minimum and maximum temperature
alarms can be excluded for a certain time
a from start-up and/or after a defrost.
These functions can be customised by
setting some programming parameters.
Other parameters allow to suite the instru-
ment to various applications.
COMMANDS ON FRONT PANEL
The instrument is provided with two keys:
"UP" and "SET/DOWN".
SET/DOWN: by pressing and releasing it
the Setpoint is displayed, the "SET" led is
turned on.
To change the Setpoint value use the "UP"
and "SET/DOWN" keys within 5 seconds.
If no operation is performed for more than
5 seconds normal mode is restored and
the new value is automatically acquired.
The same button is used to increase val-
ues during Setpoint change or parameters
programming. When held pressed a fast
increase is performed.
UP: button used to increase values. It is
used to change both the Setpoint and the
parameters. When held pressed a fast in-
crease is performed. When held pressed
for more than 7 seconds, this key also al-
lows manual activation of the defrost cycle
(the function is not enabled
Setpoint or parameter programming).
The "DEFROST" led blinks during manual
defrost.
Led "COMPRESSOR": led related to the
compressor relay. On when the compres-
sor is operating.
Led "SET": on during Setpoint setting and
displaying, blinking during parameters pro-
gramming.
Led "DEFROST": led related to defrost.
On when defrost is in progress, blinking in
case of manual defrost.
Led "ALARM": on in case of probe alarm
or high/low temperature alarm.
DISPLAYING AND SETTING THE
SETPOINT
To display the Setpoint value press and re-
lease key "SET/DOWN"; the Setpoint is
during