µRack
Cod. CAREL +03P220431 rel. 0.0 del 08/09/05 - preliminary version
18
6. Various settings
6.1. Manual device operation
The individual devices can be activated manually, ignoring the times and the rotation, and independently from the temperature control functions, by setting the
related parameters Mxx.
The only support provided in manual operation is the alarm management function.
The manual activation of the speed controllers sets the corresponding outputs to the maximum value.
When even just one manual procedure is enabled, the “MANUFACTURER” icon on the display will FLASH!
If switching the board off and on again, the function is terminated.
Important: Use this function with care! Operating the devices manually may cause damage to the installation!
6.2. Compressor hour counter and maintenance alarm
Parameter C07 is used to set the alarm threshold for the maintenance of the 4 compressors.
This parameter is expressed in the tens of hours, as the resolution of the display is only 3 digits.
Parameters C08 C10 C12 C14 are used to check the number of operating hours of the compressors installed.
These parameters are also expressed in the tens of hours, as the resolution of the display is only 3 digits.
Parameters C09 C11 C13 C15 are used to reset each individual hour counter.
The compressor maintenance alarm is shown by an alarm code, as well as by the simultaneous activation of the Maintenance and Alarm icons.
6.3. Set point variation from digital input
This function is useful when needing to increase or decrease the set point during night-time operation.
An offset is added to the compressor set point when the multifunction input, set for this function, is closed.
The offset can be defined using parameter C16.
6.4. Type of refrigerant
By selecting the type of refrigerant used in the installation(parameter /35), the software will automatically calculate the conversion of the pressure to temperature.
The following table lists the types of gas managed:
Refrigerant Complete name
R134a Tetrafluoroethane
R290 Propane
R600 Butane
R600a 2-methyl propane (isobutane)
R717 Ammonia (NH3)
R744 Carbon dioxide (CO2)
R404A,R407C,R410A,R507C Mixes of gases
6.5. Auxiliary probe management
The software can manage two auxiliary temperature probes, in addition to the suction and discharge probes.
The two probes can be configured with parameters /21 and /22:
No. Channel NTC probe
1 B2 -room temperature probe, read-only
-auxiliary probe
2 B3 -outside temperature probe for Floating condenser control
-auxiliary probe
If the auxiliary probe selected, a high temperature threshold can be set (parameter A16, A17). This alarm has automatic reset, with a fixed differential of 2°C.
6.6. Prevent high discharge pressure
This function is enabled by parameter /32.
In order to prevent the activation of the general high pressure switch (total shutdown of the compressors, with manual reset), a “prevention” function can be
enabled by setting a pre-alarm threshold; this function gradually decreases the capacity of the unit.
The high pressure prevention (Prevent HP) function is only enabled during the activation and deactivation of the compressors.
If the discharge pressure exceeds the threshold set (parameter /33), the activation of any compressors is disabled and a prevent alarm is generated. In addition, all
the compressor load steps are deactivated, observing the times set for parameter C06.
If the discharge pressure falls below the Prevent threshold, any other compressor start calls are ignored, for a set time called Prevent time 1 (parameter A13).
temperature
Alarm OFF
Set Point
Alarm ON
Diff. 2°C
Example of HT alarm management
To Next Page
Loading...