Control Functions On The Module - Hitachi SAMURAI Series Service Manual

2 Control Functions

Control functions on the module

2.1 Control functions on the module

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List of the main control functions
Item
1
Slide valve control
The outlet water temperature of the chiller unit is detected with a thermistor, and the stroke of slide valve is
controlled continuously by time-sharing.
Capacity control range: 100~25%, Stop.
2
Thermo ON-OFF control
When operation load becomes light, outlet water temperature falls below the "Stop temperature range" against
the lower limit temperature in neutral zone (in the case of cooling operation; increase in the case of heating
Automatic water
operation). By doing so, the compressor stops (Thermo OFF).
temperature control
The settings of stop temperature range can be changed locally between 0.5 and 2.0ºC (in 0.5ºC steps).
Example of cooling operation:
Also, in case that water temperature increases above "Recovery temperature range" against inlet temperature
when Thermo ON is set (in the case of cooling operation; decrease in the case of heating operation), the
compressor starts (Themo ON). (However, there is a time guard with a minimum of 3 minutes )
It is possible to change the settings of recovery temperature range, but take into account that the water volume
necessary to maintain the frequency of compressor run/stop will be different.
Once that "Compressor delay time" has passed after pump startup, compressor starts up with -Δ control,
performs startup unload control during 60 seconds, and then shifts to capacity control.
The settings of Compressor delay time can be changed in the range between 30 seconds and 10 minutes (in
Compressor Control
30 second steps).
Set a delay time adjusted to the characteristics of the installation, to prevent compressor startup until a
sufficient flow of cold water can be ensured after pump startup. Default: 30 seconds.
Compressor is temporarily stopped when a momentary power failure (drop of more than 20% of power source
Recovery from
voltage detected for a period between 13 milliseconds and 2 seconds) occurs, and it is automatically restarted
momentary power
after time guard time has passed. Also, momentary power failure detection signal is output during 10 seconds
failure
upon detection of momentary power failure.
It is possible to restart automatically after recovery from a power interruption (or power source OFF) exceeding
2 seconds.
?
N O T E
Automatic recovery
from power
• It returns to the state immediately before the occurrence of power interruption. In case that the unit was
interruption
stopped before power interruption, it remains stopped.
(Option)
• Since this function is optional, it is necessary to make the settings for the enabling of this function at the time
of local installation.
• Since there is the possibility that operation starts abruptly upon power ON, given the circumstances at the
time of power OFF, be careful enough when enabling this function.
Reverse prevention The status of the three phases of power input is monitored, to prevent operation in reverse and open phase.
6 SMGB0120 rev.0 - 11/2017
Example of cooling operation:
Setting Temperature
Lower limit in
neutral zone
Description
Outlet Water Temperature
Load up area
Load down area
Outlet water temperature
Stop temperature range Thermo OFF
Neutral Zone
(Hold)