GENERAL DESCRIPTION
The EWDR 72 has been designed specifi-
cally to be used as defrost timer in refriger-
ation systems.
The EWDR 72 comes in a 4-module DIN
housing suitable for DIN-rail mounting. As
with the EWTS 70, it controls the intervals
between defrost cycles (adjustable from
2 to 30 hours, in 2 hour increments) as well
as the duration of the defrost (from 1 to 60
minutes).
Likewise, the defrost output can also be
controlled by a klixon-type device (not
supplied); in addition, a button is provided
on the front panel to perform a manual de-
frost. The EWDR 72 also provides fan cut-
out during the defrost as well as restart of
the fan subject to a time delay (adjustable
with a trimmer).
The adjustment of times and temperatures
is extremely easy as it is obtained by
means of mini trimmers indicating the set-
ting and mini switches which are selec-
table according to a table printed on the
instrument itself. On its front side a series
of leds permits the read-out of the running
cycle (normal defrost, fan delay).
This defrost timer provides an esthetical
match with the corresponding ELIWELL
temperature controllers, i.e. EWDR series
(DIN-rail mount). The combination of an
ELIWELL defrost timer and an ELIWELL
temperature control provides a compre-
hensive and easy to operate modular con-
trol system which fits attractively in any
modern refrigeration or freezer unit.
PANEL LAY-OUT AND SYSTEM
SET-UP
“POWER” led
: green “power on” light.
“DEFROST” led
: red “defrost in progress”
light.
“FANS” led
: green status light for the
fan(s): it stays on to indicate that the fan is
running; it flashes when the fan is in a de-
lay-before-start mode (i.e. after a defrost).
“DEFROST INTERVAL” dip-switches
(1, 2, 3 and 4): to select the time interval
between the defrost cycles. The required
setting is achieved by adding the values
assigned to each of these 4 dip-switches.
For instance, by setting only switch 1 (val-
ue = 2) at “ON”, the defrost frequency is 2
hours; a 6-hour frequency is achieved by
setting switches 1 and 2 in the “ON” posi-
tion, with 3 and 4 in “OFF”.
“DEFROSTING TIME” trimmer
: screw-
driver operated slotted trimmer for the set-
ting, in minutes, of the desired length of a
defrost cycle.
“FAN DELAY TIME” trimmer
: screwdriv-
er operated slotted trimmer to set the time
delay (in minutes) for the fan, after a defrost
cycle or after system start-up.
“MANUAL” button
: pushbutton to start a
defrost cycle manually.
OPERATION
The green ”POWER” status light will come
on as soon as power is connected to the
instrument. The fan remains off according
to the selected fan time delay which is in-
dicated by the flashing green “FANS” led.
After this time delay the fan is started and
the green “FANS” light stops flashing
(stays on steady).
A timed defrost cycle is started automati-
cally: the corresponding relay is energized,
provided however that the klixon input is
closed (install a jumper if this input is not
HOW IT IS MADE
• Housing material: self-extinguish
ABS plastic
• Dimensions: 4-module DIN,
70x85 mm front
• Mounting: on DIN-rail (omega 3)
or wallmount
• Connections: terminal block for
max 2.5 mm
2
wiring
• Defrost frequency: from 2 to 30
hours, in 2-hour increments
• Length of defrost: from 1 to 60
minutes
• Klixon-type input: terminals for re-
mote klixon signal (for tempera-
ture termination)
• Manual defrost: push-button pro-
vided
• Defrost output: SPDT relay 8(3)A
250V AC
• Fan delayed start: adjustable be-
tween 1 and 10 minutes
• Fan control output: SPDT relay
8(3)A 250V AC
• Power absorption: 160 mA max
• Power supply: 220/110 Vac,
50/60 Hz or 12 Vac/dc. Others on
request
WHAT IT IS
The EWDR 72 has been designed
specifically to be used as defrost
timer in refrigeration systems.
EWDR 72
rel. 9/96 ing
defrost timer DIN rail
