Switch For Confi Rmation Of High Pressure Cut; Antifreeze Control In Winter - Hitachi RCUE40AG2 Service Manual

Control system

Switch for confi rmation of high
pressure cut

PCBa1

PCBa2
pag. 69
4.13. Switch for confi rmation of high pressure cut
Switching to this test mode makes easy to confi rm if the device for cutting high pressure
is activated.
Operation method

To Stop/Start all fans of each cycle follow the below table:
−
PCBa1 SW9
Cycle 1
Cycle 2
Cycle 3
PCBa2 SW9
Cycle 4
Cycle 5

4.14 Antifreeze control in winter

It happens sometimes that chilled water temperature is decreased so much that heat
exchanger of water side or piping system are frozen during operation stop in winter.
This control prevents Chiller unit from freezing by operating chilled and warm water
circulation pump automatically after detecting ambient and chilled water temperature.
1. Ambient temperature is below 2°C
When ambient temperature is below 2°C, operation order is sent to pump and
continuos operation of chilled water circulation pump is started automatically.
When chilled water is over 15°C, intermittent operation (5 min of operation and
55 min of stop) is performed.
SMGB0003 rev.0-01/2007
Switch for confi rmation of high
pressure cut
After unit is operated (cooling) in local
operation mode, press the switch
"confi rmation of high pressure cut",
and the fan corresponding to every
compressor is stopped forcedly. And unit
is stopped by alarm since the pressure
of high pressure side is increased, which
makes high pressure cut device activated.
Perform unit stop operation to release
alarm stop and fan forced stop.
SW10
SW10
4 4