Expansion Valves; Compressor Rotation Speed - Hitachi RAM-55QH5 Service Manual

MODEL RAM-55QH5

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.
Power
Unit 1
Unit 2
Heating output
Cooling output
Turns on
for cooling
Turns on
for heating
Outdoor fan
Operation
Rush-in
prevention
Power
approx. 100ms
Compressor
rotation speed
Hold
520
480
Unit 1
0
Hold 500ms
Hold
520
480
Unit 2
0
TSKTM1, SDRCT1, SDSTEP, TSKSPT, CMAX2, PSTART and PSTARTH are EEPROM data.
1s
1s
1s
100ms
Outdoor temperature ≥ STARCTP_C
Outdoor temperature ≤ STARCTP_C
Start enabled
Outdoor temperature ≥ STARCTP_C
Outdoor temperature ≤ STARCTP_C
31.25pps
Outdoor temperature ≥ 40˚C
Hold
Initialization finished
Outdoor temperature ≥ 40˚C
Hold
Hold 500ms
Cooling
Cooling
Start sequence
TSKTMI_C1
SDSTEP min
TSKTMI_C2
sec.
SDRCTI_C1
SDRCTI_C2
PSTARTC2K$
< TD control +
PSTARTC2$
PSTARTC2K$
< TD control +
PSTARTC2$
– 60 –
CMAX2
-1
/TSKSPT
N correction + distribution control >
N correction + distribution control >