Hitachi RAM-55QH4, Service Manual

Page: 52 / 109

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Power
Heating output
Cooling output
Compressor
rotation speed
Unit 1
Unit 2
Hold
Hold
Hold 500ms
Hold 500ms
Hold
Hold
PSTARTC2$
PSTARTC2$
Initialization finished
< TD control + N correction + distribution control >
31.25pps
Start enabled
approx. 100ms
Start sequence
SDSTEP min
-1 /TSKSPT
sec.
CMAX2
Cooling
Cooling
100ms
1s
1s
1s
520
480
0
520
480
0
Outdoor fan
Turns on
for cooling
Turns on
for heating
Operation
Power
Rush-in
prevention
Compressor
P
o
w
er rela
y
Expansion v
alv
e
Re
versing
valv
e
Unit 1
Unit 2
PSTARTC2K$ Outdoor temperature
≥
40˚C
TSKTMI_C1 Outdoor temperature
≥
STARCTP_C
TSKTMI_C2 Outdoor temperature
≤
STARCTP_C
SDRCTI_C1 Outdoor temperature
≥
STARCTP_C
SDRCTI_C2 Outdoor temperature
≤
STARCTP_C
PSTARTC2K$ Outdoor temperature
≥
40˚C
< TD control + N correction + distribution control >
MODEL RAM-55QH4
Expansion valves
The expansion valves are initialized when power is supplied. The valve for unit 1 is fully closed (–520
pulses), and then that for unit 2 is fully opened (480 pulses). The valve for unit 2 is fully closed (–520
pulses). When the valve for unit 1, 2 is fully closed (0 pulse), start-up is possible.
The start openings are held during the steady speed period when the compressor is started. After the
steady speed period is finished, the TD control is entered. The start openings are set to PSTARTH when
the outdoor temperature at start 40˚C or more, and to PSTART when it is less than 40˚C.
Compressor rotation speed
When the compressor is started, the SDRCT1 speed / TSTKTM1 second is held.
After the steady speed period is finished, the speed increases at the rate of SDSTEP speed / TSKSPT
second until the target speed is resched.
TSKTM1, SDRCT1, SDSTEP, TSKSPT, CMAX2, PSTART and PSTARTH are EEPROM data.