Control Specification
SiBE07-618_C
40
Function and Control
3.11.6 Disconnection of the Discharge Pipe Thermistor
Outline
The disconnection of the discharge pipe thermistor is detected by comparing the discharge pipe
temperature with the condensation temperature. If the discharge pipe thermistor is
disconnected, the electronic expansion valve opens according to the outdoor temperature and
the operation frequency, and operates for a specified time, and then stops.
After 3 minutes of waiting, the operation restarts and checks if the discharge pipe thermistor is
disconnected. If the discharge pipe thermistor is disconnected, the system stops after operating
for a specified time.
If the disconnection is detected 4 times in succession, then the system is shut down. When the
compressor runs for 60 minutes without any error, the error counter is reset.
Detail
Detect Disconnection
When the starting control (cooling : 640 seconds, heating : 660 seconds) finishes, the following
adjustment is made.
1. When the operation mode is cooling
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe tempe 6°C < outdoor heat exchanger temperature
2. When the operation mode is heating
When the following condition is fulfilled, the discharge pipe thermistor disconnection is
ascertained.
Discharge pipe tempe 6°C < indoor heat exchanger temperature
Adjustment when the thermistor is disconnected
When the disconnection is ascertained, the compressor continues operation for 9 minutes and
then stops.
When the compressor stops repeatedly, the system is shut down.
3.11.7 Control when frequency is changed
When the target discharge pipe temperature control is active, if the target frequency is changed
for a specified value in a certain time period, the target discharge pipe temperature control is
canceled and the target opening of the electronic expansion valve is changed according to the
shift.
3.11.8 Target Discharge Pipe Temperature Control
The target discharge pipe temperature is obtained from the indoor and outdoor heat exchanger
temperature, and the electronic expansion valve opening is adjusted so that the actual
discharge pipe temperature becomes close to the target discharge pipe temperature. (Indirect
SH (superheating) control using the discharge pipe temperature)
The electronic expansion valve opening and the target discharge pipe temperature are adjusted
every 20 seconds. The target discharge pipe temperature is controlled by indoor heat
exchanger temperature and outdoor heat exchanger temperature. The opening degree of the
electronic expansion valve is controlled by followings.
♦
Target discharge pipe temperature
♦
Actual discharge pipe temperature
♦
Previous discharge pipe temperature
SC
SH
The target discharge pipe
temperature is set as to become
the aiming SH.
The inclination does not change
depending on the operating condition.
(Supercool)
(Superheat)
