Hitachi RAM-60QH4 Manuel De Service page 66

PROCESSING AT OVERHEAT THERMISTOR (OH) HIGH TEMPERATURE
◇ Restriction Start Conditions
• If any expansion valve is operated at 480 pulses and the OH temperature > [NDOWN_ON], the compressor speed will be
reduced at a rate of 100 min
• This reduced rotation speed is based on the speed when the reduction started, and will be maintained until the reduction is
finished. However, the reference speed will be exchanged only if the target speed is lower than the speed when the
reduction started.
• If [NDOWN_OFF] ≦ OH temperature ≦ [NDOWN_ON] and the OH temperature does not rise from that 20 seconds
before, the reduction of compressor speed will not occur.
◇ Restriction Release Condition (in common for all)
• The restriction will be released when OH temperature < [NDOWN_OFF], and the compressor speed will be increased at a
rate of 50 min -1 /30 seconds to restore the target speed.
When two units are operated for heating:
Unit 1
Unit 2
Cooling output
Heating output
Turns on
for cooling
Outdoor fan
[NDWN_ON]
[NDWN_OFF]
Compressor
rotation speed
※
• Operation with one unit in heating or cooling mode and with two units in cooling mode is the same as in the above diagram.
• WMAX2 and MINRPM are EEPROM data.
-1 /30 seconds.
WMAX2
Decreases by 100 min
-1
/30sec.
Increases by 50 min
MINRPM
– 78 –
-1 / 30sec.
WMAX2