Daikin VRV RXYQ72-384XAYCA, Service Manual

Page: 92 / 419

Startup Control SiUS342004EB
85 Part 4 Functions and Control
Reference
4. Startup Control
This control is used to equalize the pressure in the suction and discharge sides of the compressor
prior to 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 or else after the startup, the following control
is made and the position of the four way valve is also determined. Start both the master and the
slave units simultaneously to position the four way valve.
4.1 Startup Control in Cooling
Refer to page 93 for Step X.
DSH : Discharge pipe superheating degree
Pc : High pressure sensor detection value
Pe : Low pressure sensor detection value
Ta : Outdoor air temperature
0 Hz
0 pulse
3,000 pulse (fully open)
Step 15
Pc – Pe > 0.42 MPa (60.9 psi)
DSH > 10°C (18°F)
Pc – Pe > 0.32 MPa (46.4 psi)
20 rps or more
OR &
Ta < 20°C: OFF
(68°F)
Ta

20°C: StepX/2
(68°F)
Frequency step up
5 sec. interval
+3step/15 sec. (Pc > 2.16 MPa (313 psi))
–3step/15 sec. (Pc < 1.77 MPa (257 psi))
Compressor
(M1C)
Electronic expansion
valve (main)
(Y1E)
Fan motor
(M1F + M2F)
Pc – Pe > 0.17 MPa (24.7 psi)
A
B
C
D
E
19
24
29
38
57 16.4
16.4
18
24
36
A
B
C
D
E
Frequency
(rps)
RXYQ72-120XA
RXYQ72-120XB
RXYQ144/168XA
RXYQ144/168XB