8 Electrical checks of main parts
Thermistor
SMGB0136 rev.0 - 07/2021
167
8
Thermistor for discharge gas temperature (THM9)
1 A thermistor for the upper part temperature of the
compressor is installed to prevent discharge gas
from overheating.
- If discharge gas temperature increases
excessively lubricating oil deterioration occurs
and lubricating properties deteriorate resulting
in short compressor life.
2 If discharge gas temperature increases excessively
compressor temperature increases. At the worst
compressor motor winding will be burnt out.
3 When the upper part temperature of compressor
increases during heating operation the unit is
controlled according to the following method.
- An electronic expansion valve of outdoor units
is (are) opened to return the liquid refrigerant
to the compressor through the accumulator
decreasing compressor temperature.
- If the compressor upper part temperature
increases exceeding 132 ºC even if an
electronic expansion valve opens the
compressor is stopped in order to protect the
compressor.In cooling operation the above
function is also available.
4 If compressor upper part temperature increases
excessively the protection control is activated
and the compressor is stopped according to the
following method.
7,47
9.93
13.4
35.1
72.3
18.7
25.1
49.9
Thermistor resistance characteristics
Temperature (ºC)
Thermistor resistance (kΩ)
Operation Upper part temperature of compressor Defecting period
Cooling
Over 132 ºC 10 minutes (continuously)
Over 140 ºC 5 seconds (continuously)
Heating
Over 132 ºC 10 minutes (continuously)
Over 140 ºC 5 seconds (continuously)
Defrosting Over 132 ºC 5 seconds (continuously)
Thermistor for outdoor ambient temperature (THM7)
0
-15 -10 -5 0510 15 20 25 30 35 40 45 50 55 60
26.0
20.2
15.9
12.6
10.0
8.05
5.31
3.60
2.49
33.7
44.0
58.3
78.0
6.52
4.36
2.99
Thermistor resistance characteristics
Ambient temperature (ºC)
Thermistor resistance (kΩ)
To Next Page
Loading...
