Technical Manual Cold Storage Controller EVP 3150-1 and EVP 3150-2
Page 10
The EVP allows several, different defrost methods.
Up to 3 defrost relays can be assigned. This relay
output(s) then control an electric heater or fan which
defrost the evaporator(s).
Each evaporator with electric heater is monitored
by a defrost termination sensor.
According to the application, the fan can stop or run
during the defrost cycle.
●
"
d02
" (Defrost Page) fixes the defrost initiation
mode.
- "
Etn
" : Defrost is initiated by a digital input
- "
Int
"
: Defrost can be initiated by digital
input or the internal time-switch.
- "
AdA
": Defrost is controlled by the intelligent
(adaptive) defrost algorithm
Electric defrost heaters are always switched by the
N/O contact of the defrost relay. "
L33
" shows the
remaining time up to the end of the defrost cycle.
Defrost release by internal timer
With parameters "
d11
"..."
d16
" (Defrost Page) you
set six (6) possible defrost release times. This
points-in-time can be set in 10 minute steps only,
that means a defrost time like 6:55 is impossible.
Times on the display:
The precondition for the start of a defrost cycle is
that at least one of the defrost termination sensors
detects a temperature below limitation temperature.
If parameter
"
d02
" is set to "
Etn
" (external only), a
defrost cycle cannot be initiated by the timer.
Please note that this function differs
with the 'adaptive' defrost method
External (Remote) Defrost Initiation
To start de-icing by a digital input, note that mains
phase has to be applied for 2 seconds minimum
and last not longer than the shortest possible
defrost cycle.
Break before defrost
Parameter ‘
d38
’ (defrost page) effects a delayed
energizing of the heater at the beginning of the
defrost cycle. By this, the rest of the evaporators
chillness can be blown to the storage.
The defrost heaters must deliver less energy,
because the evaporator is already warmed up.
Defrost termination by temperature
The EVP controller is able to work with up to 3 defrost
relays (= evaporators). Defrost is individually temi-
nated for each defrost output by the corresponding
defrost (evaporator) sensor. This evaporator sensor
must be placed at a position where, by experience,
ice remains the longest time. If the temperature rises
at that position, the ice in the evaporator is probably
melted completely.
A defrost cycle is completed as soon as the defrost
sensor has reached the defrost limitation tempera-
ture "
d31
" (Defrost Page).
If 2 defrost sensors are assigned, both sensors
must achieve the limitation temperature to termi-
nate defrost.
Defrost termination by time
If no defrost sensors are assigned or if they are out
of order, the defrost cycle will be terminated after
"
d32
" (Defrost Page) has been run down. "
L33
"
shows the remaining time up to termination.
Defrost termination time monitoring
The unit captures the number of defrost cyles which
are terminated by time (min. 1 defrost term. sensor
must be assigned). If the number of defrost cycles
terminated by time exceed the number programmed
by "
d37
" (Defrost Page) an alarm message will
be generated. With this function, massive icing or
defective defrost heaters can be recognized timely
and reliable.
In case of airflow-defrost without evapora-
tor sensor, this function must be disabled
("
oFF
"), because here every defrost will be
terminated by timer and no alarm message
is desired.
Cooling Delay (drain time)
After defrost is terminated, the solenoid valve keeps
locked for the time set by "
d35
" (Defrost Page).
"
L34
" shows the remaining time up to the restart
of cooling.
Manual Defrost
A manual defrost initiation is possible at any time.
To start manual defrost:
Select "
d50
" (Defrost Page),
set it to "
on
" and confirm.
Stop manual defrost
Select "
d50
" (Defrost Page),
set it to "
oFF
" and confirm.
3rd position =
Minutes x 10, that
means no single
minutes will be dis-
played
1st/ 2nd position =
hours
Pulsed Defrost
To save energy it’s possible to work with a pulsed
(switched in intervals) defrost function.
If the evaporator temperature is located within "
d34
"
(Defrost Page) and the limitation temperature "
d31
"
(the value of "
d34
" must be lower than limitation
temperature), the controller determines about the
optimal heat distribution in the evaporator depending
on the gradients of the temperature. The heater will
be switched on in controlled periods until the defrost
limitation temperature is reached.
The result of this procedure:
●
Heat energy in the evaporator will be distributed
much better
●
Defrost limitation temperature can be set to a
lower value
●
Less of humidity in the chamber
●
Save of energy
Defrost
