Hitachi RCME-AH1, Руководство по обслуживанию

Страница: 53 / 174

2. Control Functions
Control of the cooling cycle
SMGB0082 rev.1 - 07/2015
45
2
2.2.2 Fan Control
1 Cooling operation
This product uses fan revolution control by means of inverter to control high pressure.
The target pressure is set from outdoor temperature, and the variation of the number of revolutions is managed by PI
control. There is no switching of the number of units.
Max Frequency Min Frequency
RCME-40AH1 52Hz 7Hz
RCME-50AH1 57Hz 7Hz
RCME-60AH1 60Hz 7Hz
RCME-70AH1 60Hz 7Hz

Image diagram of fan control
Silence priority mode
Night shift
(*)
Standard mode
Outdoor temperature (ºC)
(*) In case of class 40HP
High
pressure
set
as
target
(MPa)
High pressure
Fan frequency
Time
The fan speeds down when the high
pressure is about to fall under the
target value
The fan speeds up when the high
pressure is about to exceed the
target value
High
pressure
set
as
target
• Operation at 7 Hz during 15 seconds after fan
startup, then shift to PI control afterwards.
• The calculation period of PI control is 10
seconds.
• The target high pressure is set according to
the image beside, but the high-low pressure
difference required by the compressor is set
with preference.
• Calculations are not performed when the target
value for high pressure lies 0/-0.1 MPa.
• The following controls are enabled to respond
to sudden changes.
High pressure over-increase prevention
• With high pressure ≥ 1.3 MPa, + 10 Hz output
• With high pressure ≥ 1.6 MPa, maximum
frequency output
• With detection temperature of liquid
temperature thermistor ≥ 56ºC, maximum
frequency output
High pressure over-decrease prevention
• With high pressure ≤ 0.3MPa, - 10 Hz output
• With high pressure ≤ 0.25 MPa, minimum
frequency output
2 Heating operation
Low pressure is controller by using fan revolution control by means of inverter.
The variation of the number of revolutions is managed by PI control, to achieve a target low pressure of 0.5 MPa. There
is no switching of the number of units. The usage frequency range is the same as in cooling operation. Also, the following
control is enabled to respond to sudden changes.
Low pressure over-increase prevention control
•
With low pressure ≤ 0.3 MPa, +10 Hz output