Control Specification
Si12-714
88
Function and Control
3.12.7 Disconnection of the
Discharge Pipe Thermistor
Outline
Detect a disconnected discharge pipe thermistor by comparing the discharge pipe temperature
with the condensation temperature. If any is disconnected, open the electronic expansion valve
according to the outdoor air temperature and the operating frequency and operate for a
specified time, and then stop.
After 3 minutes of waiting, restart the unit and check if any is disconnected. If any is
disconnected stop the system after operating for a specified time. If the disconnection is
detected 4 times in succession, then the system will be down.
Detail
Detect Disconnection
If a 630-second timer for open control becomes over, and a 9-minute timer for the compressor
operation continuation is not counting time, the following adjustment must be made.
1. When the operation mode is cooling
When the discharge pipe temperature is lower than the outdoor heat exchanger
temperature, the discharge pipe thermistor disconnection must be ascertained.
2. When the operation mode is heating (only for heat pump model)
When the discharge pipe temperature is lower than the max temperature of operating room
heat exchanger, the discharge pipe thermistor disconnection must be ascertained.
Adjustment when the thermistor is disconnected
When compressor stop repeats specified time, the system should be down.
3.12.8 Control when frequency is changed
When the target pipe temperature control is active, if the target frequency is changed for a
specified value in a certain time period, cancel the target discharge pipe temperature control
and change the opening of the target electronic expansion valve according to the shift.
3.12.9 High Temperature of the
Discharge Pipe
When the compressor is operating, if the discharge pipe temperature exceeds a certain value,
open the electronic expansion valve and remove the refrigerant to the low pressure side and
lower discharge temperature.
3.12.10 Oil Recovery Function
Outline
The electronic expansion valve opening in the cooling stopped room must be set as to open for
a certain time at a specified interval so that the oil in the cooling stopped room may not be
accumulated.
Detail
During cooling operation, every 1 hour continuous operation, the electronic expansion valves in
the operation stopped room must be opened by 80 pulses for specified time.
3.12.11
Target Discharge Pipe Temperature Control
Obtain the target discharge pipe temperature from the indoor and outdoor heat exchange
temperature, and adjust the electronic expansion valve opening so that the actual discharge
pipe temperature become close to that temperature. (Indirect SH control using the discharge
pipe temperature)
Determine a correction value of the electronic expansion valve compensation and drive it
according to the deflection of the target discharge temperature and actual discharge
temperature, and the discharge temperature variation by the 20 sec.
