LG RCWW Operation & Maintenance Manual page 82

6. Commissioning
82
Oil filling
1) the Chiller is shipped with compressor oil filled, but in case oil is not filled, please fill oil as follows:
2) Fill oil using the oil filling valve installed at the bottom of the compressor. At this time, keep the vacuum in the ma-
chine using a vacuum pump. (If you charge refrigerant first, the charged refrigerant will evaporate and thus the
pressure will rise, therefore, fill oil first. In case the pressure inside the machine is high, the oil should be filled by
pump from the oil containing vessel.) In this case, the discharge pressure of the pump should be 14 kg/cm2.G or
higher when the suction pressure is 0 kg/cm2.G. However, the oil should be either removed or filled when the
Chiller is stopped.
3) The normal oil level in the compressor oil sump should be maintained above the top of the low-level sight glass
and in the middle level of high-level sight glass when compressor is running. Also, as long as the oil pressure and
temperature stay within the limit values, the oil-foaming phenomenon is not a problem.
4) Be careful that the air should not be induced when oil is filled.
Refrigerant charging
!
CAUTION
When you charge, remove or add refrigerant from or to the machine which is loaded with spring, the spring should be
fixed not to be moved in up and down direction, so as it not to stress the connected piping. Please beware of this.
1) In case the Chiller is filled with nitrogen, remove the nitrogen at the site, and then charge the refrigerant.
2) When charging refrigerant, be sure to start the chilled water pump and cooling water pump to prevent freezing.
3) It is preferable to adjust the refrigerant amount when the chiller is running at the designed load, Adjust the amount
of refrigerant with the difference between chilled water outlet temperature and evaporation temperature and
watching through the sight glass.
Insulation resistance test
1) Megger test is to obtain the insulation resistance by measuring the leakage current which is flowing through the
insulation material by directly applying a voltage to the insulation material.
For 380 and 440V classes: use megger for 500V.
2) Please prevent access by the unnecessary personnel since high-voltage is used.
3) Conduct the test after all the external powers to the Chiller are interrupted.
4) In case of three-phase motor, a danger may be caused by the electric charge, therefore always discharge after the
test and use ground terminal.
5) In vacuum, do not conduct high voltage megger test.
6) The electrical insulation resistance decreases with the rise in temperature, changing in big span by the tempera-
ture change. When temperature change is shown as temperature coefficient, and the equation applied to tempera-
ture coefficient to the motor is as follows:
Temperature of Insulator
when testing (°C)
0
5
10
15.6
20
25
30
35
applied voltage
Insulation resistance =
leakage current
Temperature coefficient
0.4
0.5
0.63
0.81
1
1.25
1.58
2
Table 12 Temperature coefficient vs. Temperature of Insulator
Temperature of Insulator
when testing (°C)
40
45
50
55
60
65
70
75
Temperature coefficient
2.5
3.15
3.98
5
6.3
7.9
10
12.6