temperature. If necessary, through the parameters oS1, oS2 and oS3 the temperatures t1,and t2 measured by the probes can be adjusted
in order to obtain the desired values for computing: thermostat T1=t1+oS1; defrost T2=t2+oS2; display T3=t1+oS3.
Ex.: Setpoint= -20°; oS1= -2°K; oS3= +6°K, temperature t1 is controlled at -18° and the display shows -12°.
Through the SiM parameter it’s possible to reduce the fluctuations of the displayed temperature by simulating the behaviour of product core
temperature. The slowdown is proportionated to the value programmed to SiM (ex.: 100 simulates approx. a 0.5 l bottle of water). To display
the instantaneous temperatures T1, T2 or T3 press , or respectively.
3.2
DURING DEFROST.
The display is controlled according to the parameter diS, if 00 temperature T3 continues to be displayed. If diS=
-01, then the display shows “dEF” since defrost start as long as the temperature T1 is higher than setpoint+hysteresis hyS. By programming
a value between 1 and 30 min., after the defrost “dEF” is still displayed until the time programmed has elapsed unless the above condition
is reached before.
3.3
OTHER DISPLAY STATUS.
During an alarm condition, “ALM” blinks on display. The stand-by status, in which all outputs are off, is signalled
with permanent “—-”. If the keypad has been locked through the serial communication, when attempting to perform any changes, the display
shows “inh”.
4. THERMOSTAT FUNCTION
At power-up the cooler start is delayed by the sum of coF and crS; this latter is used in those applications where it is necessary, after a line
dropout, to avoid simultaneous starts of many compressors at the power-up. For ex.: coF= 03, crS= 05; after power-up, at least 03 minutes
and 05 seconds must elapse before the cooler starts. coF and con are, respectively, the cooler minimum off and on time. The relay which
controls the cooler, after switching off/on or on/off, will remain in that status for at least the pre-programmed time. When you have to maintain
a ver
y small hysteresis hyS, we recommend to program a suitable value for coF and con to ensure a long life to relay/contactor and
compressor.
Temperature control is based on the comparison between temperature T1, the setpoint and the hysteresis hyS programmed. The setpoint is
displayed by pressing . To change it, keep pressed and by pushing key or , select the desired value within the limits SPL and SPh.
The cooler on switching temperature is achieved by adding hyS to the setpoint.
Ex.: setpoint=-03; hyS=04, the relay is off with T1=-03°C and on with T1=+01°C.
When a failure or overrange of probe T1 occurs, the cooler run isn’t controlled according to setpoint but determined by cdc which represents
the cooler duty cycle, i.e. (on time)/(10 minute cycle). For ex.: 04= 4 minutes on time, 6 minutes off time. The cdc value has to be set taking
into consideration the normal cooler duty cycle.
If you wish to switch off the outputs, you can put the RDC12 on a standby via the serial communication or manually, by pressing ++
during self-check following the power-up. During the standby temperature measurement and serial communication however remain active. If
the RDC12 is on a standby, you can get it to go out of this status and resume its ordinary operation by following the same procedure as
described above .
5. DEFROST SETTINGS
Defrost is started when the real time, kept by the internal clock, matches one of the 6 scheduled times.
You have got access to clock and defrost times by keeping + pressed for 4 seconds. To move from one value to the next/previous, press
/ . To display it press , change it by pressing + or .
5.1
CLOCK PROGRAMMING.
To set the minutes of the real time, select Min and press + or . As to the hours, select hrS and proceed
as above. The clock programming range is from 00:00 to 23:59. Be careful if clock programming takes place at the end of an hour (10:59:59
- 11:00:00), if necessary check the clock again before you go further.
The real time is kept even in case of a power failure for a minimum of 5 days, typically 20 days.
5.2
DEFROST PROGRAMMING.
The six defrost start times are identified by the mnemonic dh1... dh6. The time is adjustable in hours and
tens of minutes i.e. 072 and 130 correspond to 7:20 and 13:00. The times assigned to dh1... dh6 do not need to be sequential.
If you want to eliminate one or more defrosts, simply program 240.
Two or more defrosts with time difference smaller or equal to 10 minutes are considered as one defrost. Ex.: dh1=073, dh2=073, dh3=074
there will be one defrost only at 7:30.
The defrost start times are stored in a non-volatile memory and therefore they are not lost in case of a black-out.
5.3 MANUAL DEFROST.
It is possible to manually start or abort defrost by pushing + .
6. DEFROST FUNCTION
6.1 E
VAPORATOR HEATING.
During defrost the status of the outputs is determined by parameter dty. If dty=Fan, then the evaporator fans
are kept on, while cooler and defrost outputs are off. If dty=ELE, during defrost the cooler is switched off and the defrost output on. If
dty=GAS, cooler and defrost outputs are on all through defrost.
6.2 TERMINATION.
When defrost is on, it can be terminated on either temperature, when T2 matches the dLi value, or when the maximum
time dto has elapsed.
6.3 DRIPPING.
After the heating phase, the dripping time drP, by delaying the cooler re-start, allows a homogeneous heat spread all over
the evaporator and the drain of the drops of water.
INSTRUCTIONS FOR INSTALLATION AND USE.
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