Special Control SiUS281811EA
110 Part 4 Functions and Control
3. Special Control
3.1 Startup Control
This control is used to equalize the pressure in the suction and discharge sides of the compressor
prior to compressor startup, thus reducing startup loads. Furthermore, the inverter is turned ON to
charge the capacitor.
In addition, to avoid stresses to the compressor due to oil return, 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 start up simultaneously.
Pc: High pressure sensor detection value
Pe: Low pressure sensor detection value
Ta: Outdoor air temperature
3.1.1 Startup Control in Cooling
Outdoor unit
actuator
Electric Symbol
Pressure equalization
control prior to startup
Startup control
18/24
class
30/36/42/48
class
STEP 1 STEP 2
Compressor M1C M1C 0 Hz Minimum
frequency
Increases 2 steps every 20
seconds from minimum
frequency until
Pc – Pe > 0.39 MPa
(56.6 psi) is achieved
Outdoor fan M1F M1F
M2F
STEP 7 Ta < 20°C (68°F):
OFF
Ta ≥ 20°C (68°F):
STEP 4
+1 step/15 sec. (when Pc >
2.16 MPa (313 psi))
–1 step/15 sec. (when Pc <
1.77 MPa (257 psi))
Main electronic
expansion valve
Y1E Y1E 0 pulse 480 pulse (Fully
open)
480 pulse (Fully open)
Subcooling
electronic
expansion valve
— Y3E 0 pulse 0 pulse 0 pulse
Four way valve Y1S Y1S Holds OFF OFF
Hot gas bypass
valve
Y2S — OFF OFF OFF
Ending conditions A lapse of 10 sec.
• Pc – Pe < 0.3 MPa
(43.5 psi)
•
A lapse of 1 to 5 min.
OR
• A lapse of 130 sec.
• Pc – Pe > 0.39 MPa
(56.6 psi)
OR
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