2-25
• By condenser fan control
When the ambient temperature is low during the air-cooled operation, the condenser pressure
(high pressure) will decrease. Accordingly, the low pressure will decrease.
In order to prevent this situation, when the high pressure becomes set point or lower, the
condenser fan stops to prevent the high pressure from excess dropping.
When the high pressure becomes set point or higher the condensor fan will restart.
This control varies upon dehumidification setting.
F
:
Injection control
In order to decrease the discharge gas temperature, liquid refrigerant is injected into the suction pipe.
• During normal compressor operation
The injection solenoid valve will be turned on or off to control the discharge gas temperature lower
than set point.
The control is conducted properly by using detected discharge gas temperature and inside
temperature.
• Defrosting / Heat-up operation
Control the injection ON/OFF with charge control. For details, see the section of "charge control" on
page 2-29.
G
:
In-range control
When the control temperature is close to the setting value
(SP), the in-range lamp on the display panel is lit to clearly
indicate whether the inside temperature is controlling
normally.
H
:
In-range masking control
If the inside temperature is within the in-range when
defrosting is started, the in-range lamp will be kept turned on
forcibly for certain period as below regardless of the inside
temperature thereafter.
This will avoid misunderstanding that there is a problem as the control temperature temporarily rises
during defrosting.
ON
OFF
High pressure > 1000kPa
High pressure
≦
800kPa
Dehumidification : OFF
Dehumidification : ON
ON
OFF
High pressure > 900~2100kPa
High pressure
≦
700~1800kPa
Control
temperature
SP+1 ˚C
SP
SP– 2 ˚C
SP+ 2 ˚C
SP–1 ˚C
In-range lamp
(OFF)
In-range lamp
(OFF)
In-range lamp
(ON)
Discharge gas temperature (DCHS) set value
Setpoint
≧
–20.0˚C
100 minutes
Setpoint
≦
–20.1˚C
130 minutes
Frozen, chilled (pull-down)
Chilled,
capacity control
RS
≦
0˚C
AMBS>40˚C
ISV_ON
DCHS>120˚C
Turned ON/OFF depending on
AMBS and RS
DCHS>113˚C
ISV_OFF
DCHS<110˚C
DCHS<108˚C
AMBS<40˚C
RS>0˚C
DCHS>125˚C
DCHS<118˚C
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