Special Control
SiUS181305E
45
Function
3. Special Control
3.1
Startup Control
Startup control equalizes the pressure in the front and back of the compressor before the startup of
the compressor, thus reducing startup loads. Furthermore, the inverter is turned ON to charge the
capacitor.
To avoid stresses to the compressor due to oil return operation, etc. after startup, the following
control is made and the position of the four way valve is also determined. To position the four-way
valve, the master and slave units simultaneously start up.
3.1.1 Startup Control in Cooling Operation
3.1.2 Startup Control in Heating Operation
Thermostat ON
Pressure equalization control
before startup
Startup control
STEP 1
STEP 2
Compressor
0 Hz
57 Hz Unload
57 Hz Unload
+2 steps / 20 sec.
(until Pc – Pe > 0.39 MPa (130 ftAq))
Outdoor fan
STEP 7
Ta < 20
C: OFF
(68°F)
Ta
20
C: STEP 4
(68°F)
+1 step / 15 sec.
(when Pc > 2.16 MPa (723 ftAq))
–1 step / 15 sec.
(when Pc < 1.77 MPa (592 ftAq))
Four-way valve (Y1S)
Holds
OFF
OFF
Main electronic expansion
valve (Y1E)
0 pulse
480 pulse
480 pulse
Subcooling electronic
expansion valve (Y3E)
0 pulse
0 pulse
0 pulse
Hot gas bypass solenoid
valve (Y2S)
OFF
OFF
OFF
Ending conditions
Pc – Pe < 0.3 MPa
(100 ftAq)
A lapse of 1 to 5 min.
A lapse of 10 sec.
A lapse of 130 sec.
Pc – Pe > 0.39 MPa
(130 ftAq)
or
or
Thermostat ON
Pressure equalization control
before startup
Startup control
STEP 1
STEP 2
Compressor
0 Hz
57 Hz Unload
57 Hz Unload
+2 steps / 20 sec.
(until Pc – Pe > 0.39 MPa (130 ftAq))
Outdoor fan
From starting
~ 1 min. : STEP 7
1 ~ 3 min. : STEP 3
3 ~ 5 min. : OFF
STEP 8
STEP 8
Four-way valve (Y1S)
Holds
ON
ON
Main electronic expansion
valve (Y1E)
0 pulse
0 pulse
0 pulse
Subcooling electronic
expansion valve (Y3E)
0 pulse
0 pulse
0 pulse
Hot gas bypass solenoid
valve (Y2S)
OFF
OFF
OFF
Ending conditions
Pc – Pe < 0.3 MPa
(100 ftAq)
A lapse of 1 to 5 min.
A lapse of 10 sec.
A lapse of 130 sec.
Pc > 2.70 MPa (903 ftAq)
Pc – Pe > 0.39 MPa (130 ftAq)
or
or
