Items To Be Checked Before A Test Run - Mitsubishi Electric CAHV-R450YA-HPB Service Manual

[ VIII Test Run Mode ]

[1] Items to be checked before a Test Run

VIII T est Run Mode
(1) Check for refrigerant leak and loose cables and connectors.
(2) Measure the insulation resistance between the power supply terminal block and the ground with a 500V megger and
make sure it reads at least 1.0Mohm.
Do not operate the unit if the insulation resistance is below 1.0Mohm.
Do not apply megger voltage to the terminal block for transmission line. Doing so will damage the controller board.
Never measure the insulation resistance of the transmission terminal block for the RA,RB,MA,MB(TB3). Do not attempt to
measure the insulation resistance of TB7.
The insulation resistance between the power supply terminal block and the ground could go down to close to 1Mohm imme-
diately after installation or when the power is kept off for an extended period of time because of the accumulation of refrigerant
in the compressor.
If insulation resistance reads at least 1Mohm, by turning on the main power and powering the belt heater for at least 12 hours,
the refrigerant in the compressor will evaporate and the insulation resistance will go up.
Do not measure the insulation resistance of the terminal block for transmission line for the unit remote controller.
Securely tighten the cap.
(3) Check the phase order of the 3-phase power source and the voltage between each phase.
(4) When a power supply unit is connected to the transmission line for centralized control, perform a test run with the
power supply unit being energized.
(5) Pre-energize the compressor.
Switch on the power to the case heater and keep it turned on for at least 12 hours before starting a test run.
A.
(Compression of liquid refrigerant that may happen if the unit is started up without pre-energizing the compressor
may damage the valve or cause other problems. When foaming is happening, the compressor will make cracking
sounds for a few seconds at the beginning of operation.)
B. Supply water to the water circuit before operating the pump. Operating the pump without water may damage the shaft
seal.
(6) Check the pressure.
Translate the pressure readings into saturating temperatures, and make sure these values fall into the ranges specified in the
table below.
Condensing and evaporating temperatures during operation
Saturation pressure equivalent
to refrigerant pressure
Condensing temperature
Evaporating temperature
* To maintain proper compression ratio, when the outside temperature exceeds 17 ºC, evaporating temperature may
drop below "(Outside temperature) - 8 ºC"
(7) Check that the correct voltage is applied.
Check that the voltage that is applied while the unit is stopped and the load-side voltage of the solenoid contactor in the relay
box during operation are within the voltage ranges. Check the voltage in all phases (L1, L2, and L3), and make sure that the
voltage imbalance between the phases is 2% or less.
(8) Check either the power supply current or the compressor current.
Check the compressor current in all phases (L1, L2, and L3).
(9) Check for short-cycling of discharge air.
Check that the intake air temperature is not unusually higher or lower than the outside temperature. During operation, the dif-
ference between the heat exchanger inlet temperature and outside temperature should be 1 ºC or less.
(10) Check for proper circulating water flow rate.
Measure the circulating water flow rate, if possible. If it is not, check that the temperature difference between the outlet and
inlet temperatures is between 3 and 5 ºC. A temperature difference of 6ºC or more indicates not enough water flow. Check
for air pockets in the pipe, and make sure that the pump has the appropriate capacity for the circuit.
HWE22020
Heating (outside temperature: between -25 ºC and +43 ºC)
At the initial stage of heating water
(Before water has been heated up)
Outlet water temperature + (0 - 10 °C)
Outside temp. - (5 - 13 °C)
- 113 -
During normal operation
Outlet water temperature + (0 - 5 °C)
Outside temp. - (3 - 8 °C)*
GB