DEFROST CONTROL
The instrument can be used to select dif-
ferent types of defrosting with the para-
meter
dty, defrost type
.
(defrost execution mode).
The dty parameter can have these values:
0 = Electrical or Off Cycle defrost
(Compressor OFF during Defrost);
1 = Reverse cycle defrost
(hot gas - Compressor On during Defrost);
2 = ’Free’ : Independent defrost
(compressor cycles ON/OFF according to
temperature during defrost)
Configuration of 3
rd
probe as 2nd evap-
orator probe
The 3
a
probe can be used to control the
defrosting of a second evaporator by con-
figuring a relay output as a 2nd evaporator
defrost relay (see par. H21…H26).
To implement this function:
a) configure the 3
rd
probe in 2nd evapora-
tor defrost control mode (par. H43=2EP).
b) configure a relay output as 2nd evapo-
rator defrost relay (configuration parame-
ters H21…H26).
c) define the defrost mode by setting
parameter H45.
Start of defrosting
If two evaporators are used, defrosting
starts in three different ways that are
determined by parameter H45.
• H45=0: Defrosting is enabled by con-
trolling the temperature of the 1st evapo-
rator so it is lower than parameter dSt,
•H45=1: Defrosting is enabled by control-
ling so that at least one of the two probes
is below its end of defrosting temperature
(dSt for the 1st evaporator and dS2 for
the 2nd evaporator)
• H45=2: Defrosting is enabled by control-
ling so that both the probes are below
their respective end of defrosting set
points (dSt for the 1st evaporator and dS2
for the 2nd evaporator)
The probe error condition is considered
the defrost calling probe.
When defrosting is terminated by a probe
or is timed out (see par. dEt), dripping fol-
lows (see par. dt).
End of defrosting
If two evaporators are used, defrosting
ends when both the probes have reached
or exceeded their respective end of
defrosting set points (dSt for the 1st evap-
orator and dS2 for the 2nd evaporator)
If one or both the probes are faulty,
defrosting is ended by a time-out.
NOTE:
• If there are no conditions for defrosting,
the request is ignored.
Defrosting of a single evaporator ends
when the value read by the respective
probe is equal to or higher than the end
of defrosting temperature or a time-out
occurs. Dripping starts when both defrosts
have been completed.
• If one or both the probes are faulty,
defrosting in the corresponding evaporator
is ended by a time-out.
The start of defrosting is permitted when
the corresponding temperature is lower
than the corresponding set point (dSt or
dS2).
• If probe 3 is not configured as a probe
on the second evaporator (H43
≠
2),
defrosting on the second evaporator
occurs if a digital output is configured to
control defrosting on the second evapora-
tor (see par. H21..H25). If this is the case,
defrosting is confirmed (as if ST3<dS2)
and ends with a time-out. The fan con-
troller remains unchanged.
GENERAL PRESSURE SWITCH INPUT
CONTROLLER
This controller performs diagnostics on an
associated digital input using a configura-
tion table. It is activated by setting para-
meters H11 and H12 = 9.
If the pressure switch input trips, the com-
pressor loads are immediately deactivated,
the alarm LED lights up to signal tripping
and the label nPA in the alarm folder
appears on the display.
Controlling is performed using 2 parame-
ters PEn and PEI:
nPA is a subfolder of AL (Alarms), and
keeps a record of each time the pressure
switch is activated if the value indicated by
PEn is reached in a period of time that is
less than or equal to PEI, the label nPA is
replaced by PA (pressure alarm).
The alarm conditions only occurs when the
maximum number of alarms is reached
before the time indicated by parameter
PEI expires. As soon as the first alarm
occurs, the time PEI is calculated.
If the number of times the pressure switch
is activated exceeds the number estab-
lished PEn in the period PEI:
- compressor outputs, fans and defrosting
are deactivated
- the label PA is displayed in the subfolder
nPA
- the alarm LEDs and alarm relay if config-
ured are switched on.
NOTE:
Once the device is in alarm mode,
it must be switched off and on again or
reset by activating the rAP parameter in
the functions menu. The nPA folders can
be reset using the rPA function in the Fnc
folder.
NOTE:
If parameter PEn is set to 0 the
function is excluded and the alarms and
counts are disabled.
CONDENSER FAN CONTROLLER
This controller is associated with probe
Pb3 and features:
- operating set point
- operating differential
- exclusion of fans in defrosting mode
- start-up delay after end of defrosting If a
digital output is set as condenser fans
(H21...H24=10) the output will behave as
shown below:
If probe Pb3 is not present and alarm E3 is
active, the controller will always be on
during the defrost cycle.
Probe 3 can be excluded and the failed
connection with the instrument will not
trigger an error message.
NOTE:
During dripping time the output is
OFF.
NOTE:
If a digital output is programmed
as condenser fans (H21...H25 =10) parame-
ter SA3 is always an absolute value irre-
spective of the value of parameter Att.
DIAGNOSTICS
The alarm condition is always signalled by
a buzzer (if present) and the alarm icon
LED. The alarms from the faulty thermo-
stat control probe (probe 1), the faulty
evaporator probe (probe 2), and the faulty
display probe (probe 3) appear directly on
the instrument display as E1, E2, and E3
respectively.
An error condition in probe 1 (thermostat
control) causes the following:
• E1 code appears on display
• compressor is activated as indicated by
“Ont” and “Oft” parameters if these are
programmed for duty cycle or:
The error condition for probe 2 (evapora-
tor) causes the following:
• E2 code appears on display
• end of defrost due to time-out.
The error condition for probe 3 (display)
causes the following:
• E3 code appears on display Other alarms
do not appear on the instrument display
ID 985/S/E/CK - ID985/E LX
4/14
Par.
Description
PEn
number of errors allowed per maximum/
minimum pressure switch input switch
input (number)
PEI
Minimum/maximum pressure switch error
count time (minutes)
Output Value
Pb3 Value
ON
≥
SCF OFF
≤
SCF - dCF
DISPLAY
E1
E2
E3
If simultaneous, they will be showed on the display
alternately every 2 seconds
FAULT
Faulty probe 1 (thermostat control)
Faulty probe 2 (1st evaporator)
Faulty probe 3 (display or 2nd evap-
orator)
Table of faulty probes
Ont
0
0
>0
>0
Oft
0
>0
0
>0
Compressor output
OFF
OFF
ON
dc
