Midea LSBLG365/MCFN

Flooded type water cooled screw chiller (PCB Control) MCAC-CTSM-2012-11
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IV. Maintenance and Commissioning
Engineers working on the electric or refrigeration components must be authorized, trained and fully
qualified to do so. All refrigerant circuit repairs must be carried out by a trained person, fully qualified to
work on these units. He must have been trained and be familiar with the equipment and the installation.
All welding operations must be carried out by qualified specialists.
Any manipulation (opening or closing) of a shut-off valve must be carried out by a qualified and
authorized engineer. These procedures must be carried out with the unit shut-down.
NOTE:
The unit must never be left shut down with the liquid line valve closed, as liquid refrigerant can be
trapped between this valve and the expansion device. (This valve is situated on the liquid line before the
filter drier box.)
ATTENTION:
Even if the unit has been switched off, the power circuit remains energized, unless the unit or circuit
disconnect switch is open. Refer to the wiring diagram for further details. Attach appropriate safety
labels.
At least once a year thoroughly inspect the protection devices (valves). If the machine operates in a
corrosive environment, inspect the protection devices more frequently.
1. Commissioning
1.1 Electrical System Connection Inspection
1) Inspect whether power distribution capacity is compliant with the power of the unit before the first
start-up, and whether the diameter of the selected cable can bear the maximum working current
of the master compressor.
The max economical conveying distance:
The max loading time in a year（h）
Copper core length(m)
<3000h 264
3000～5000h
294
>5000h 331
2) Inspect whether the electric mode is compliant with that of the unit, three-phase five-line (three
phase lines, one zero line and one earth wire, 380V±10%).
3) Inspect whether the maximum phase voltage unbalance is compliant with the requirement, 2%
for the maximum permissible phase voltage unbalance and 5% for the phase current balance.
The machine must not be started up when the phase voltage unbalance exceeds 2%. If the
measured unbalance% is excess, the power supply sector shall be informed of immediately.
The formula for calculation of phase voltage unbalance% based on the maximum deviation
from the average voltage is: voltage unbalance% = maximum deviation from average
voltage/average voltage.