Hitachi RWM-(H)FSN3E, Руководство по обслуживанию

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9 Electrical checks of
the main parts
SMGB0070 rev. 1 - 08/2011
228

Thermistor for upper part temperature of compressor
(For prevention of discharge gas overheating)
a. A thermistor for the upper part temperature of the compressor is installed to prevent discharge gas from overhea-
ting.
If discharge gas temperature increases excessively lubricating oil deterioration occurs and lubricating properties
deteriorate, resulting in short compressor life.
b. If discharge gas temperature increases excessively, compressor temperature increases. At the worst, compressor
motor winding will be burnt out.
c. When the upper part temperature of compressor increases during heating operation, the unit is controlled accor-
ding to the following method
Š
An electronic expansion valve of outdoor units is (are) opened to return the liquid refrigerant to the compressor
through the accumulator, decreasing compressor temperature.
Š
If the compressor upper part temperature increases exceeding 132ºC even if an electronic expansion valve
opens, the compressor is stopped, in order to protect the compressor.
Š
In cooling operation, the above function is also available.
Temperature (ºC)
Resistance characteristics of thermistor for
discharge gas overheating protection
Resistance
value
of
thermistor
(kΩ)
200
200
100
0
25 30 100 132 150
R25 = 200kΩ
B = 3920k
72.3
14.2 5.3
d.
If compressor upper part temperature increases excessively, the protection control is activated and the compres-
sor is stopped according to the following method.
Operation Upper part temperature of compressor Defecting period
Cooling
Over 132ºC 10 minutes (continuously)
Over 140ºC 5 seconds (continuously)
Heating
Over 132ºC 10 minutes (continuously)
Over 140ºC 5 seconds (continuously)
Defrosting Over 132ºC 5 seconds (continuously)