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ENGLISH
ir33 +030220441 - rel. 2.0 - 01.05.2006
cc: Continuous cycle duration
This is the time (in hours) during which the compressor operates continuously to lower the temperature,
even below the set point. With cc=0 => the continuous cycle is disabled. The controller exits the conti-
nuous cycle procedure after the time set for parameter cc has elapsed, or upon reaching the minimum
specifi ed temperature (see the minimum temperature alarm, parameter AL). Default: cc=0 (hours).
Note: if control with two compressor steps is selected (with or without rotation, ‘H1’= 12 or 13), the
continuous cycle acts on both steps
c6: Alarm bypass after continuous cycle
This is the time (in hours) for which the temperature alarm is deactivated after a continuous cycle. If the
temperature of the refrigeration unit, after the continuous cycle, falls due by inertia below the minimum
temperature (set point – AL), the activation of the low temperature alarm is delayed for time c6.
Default: c6=2 (hours).
Warning: remember that at the minimum specifi ed temperature (see the minimum temperature alarm,
parameter AL) the continuous cycle is forced OFF and deactivated.
c7: Maximum pump down time
This parameter determines, depending on the setting of parameter c10, the maximum time in minutes
by which the circuit must reach the required low pressure value in pump down operation (c10=0), or the
compressor operating time after the closing of the pump down valve in case of pump down operation
by time (c10=1). The pump down valve must be connected to the auxiliary output, setting the relevant
parameter (H1).
Pump down by pressure (c10=1):
When reaching the maximum pump down time, the compressor stops and the Pd alarm is activated,
which disables the compressor autostart function (see parameter c9) with the pump down valve closed,
on the “high pressure” request from the pressure switch. The compressor remains OFF until the controller
requires cooling. When reaching the set point, a pump down procedure is run and the alarm is
automatically reset if the low pressure is reached within the time c7.
Low pressure is monitored by connecting the low pressure switch to one of the two digital inputs and
setting the parameter A4 or A5.
Pump down by time (c10=1):
When the compressor operating time c7 is reached after the opening of the valve, the compressor
is stopped, irrespective of the low pressure reading, and the Pd alarm is deactivated. In any case, the
compressor is stopped when reaching the low pressure.
In this case, autostart in pump down is disabled. Default: c7 =0 => pump down disabled.
c8 : Compressor start delay after opening of PD valve
This parameter determines after how many seconds from the opening of the pump down valve the
compressor starts. It is useful to avoid activating the LP alarm unnecessarily.
The low pressure alarm (LP), with valve open and compressor ON, is activated by the opening of the
pressure switch. This alarm stops the compressor and is reset automatically.
The parameter is active if c7=0. Default: c8=5 => 5 seconds delay.
c9: Enable autostart function with PD operation (active when C7=6)
If the parameter is set to 0, the system will perform a pump down cycle each time the pump down valve
closes. If the parameter is set to 1, on the other hand, the system will perform a pump down cycle each
time the pump down valve closes and on each successive request from the low pressure switch when
there is no cooling requirement (autostart situation). The autostart function is disabled if Pd alarms are
active or if pump down by time is selected.
Note: the autostart function is disabled in the off status and if the controller has been switched on but the
compressor has not yet been activated (after the fi rst activation of the compressor, the autostart function, if
selected, will be always active).
Default: c9=0 => only one pump down cycle is run whenever the pump down valve is closed.
c10: Select pump down by pressure or by time
This parameter determines if the pump down procedure must end following the activation of the low pressure
switch, or after a set time. In this case, after the valve closes, the compressor works for time c7 or until the low
pressure value is reached. When this time has elapsed, the compressor is stopped, irrespective of the status of
the low pressure input.
The Pd alarm (pump down ended by timeout) and the compressor autostart function in pump down are
disabled
Default: c10=0 => pump down by pressure.
c11: Second compressor delay
This parameter determines the delay of the second compressor, compared to the main compressor,
during start-up (‘H1’=7). Vice-versa, the two compressors are stopped at the same time.
If two compressor steps have been selected (‘H1’=12, 13), the parameter c11 represents the delay for the
activation of the second step from the fi rst.
Important: select the auxiliary output as a delayed compressor or second compressor step using
parameter ‘H1’.
Default: c11=4 => 4 second delay.
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