Gree GMV-224WM/B-X, Service Manual

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GMV5 DC INVERTER VRF UNITS SERVICE MANUAL
102
2.4 Electrical System Check
1) Check for high electromagnetic interference, dusts, and acidic or alkaline gas in the unit
environment.
a. The air conditioning unit can neither share the same power supply system with the equipment
containing variable-frequency drives, nor reside near the equipment generating high electromagnetic
interference. Otherwise, the air conditioning unit may fail to properly work due to interference. If this case
exists, records should be made. In the case of serious influence, the air conditioning unit must be
relocated or relevant measures must be taken.
b. Prevent acidic or alkaline gas/liquid from rusting cables of the air conditioning unit.
2) Check the installation appearance of power cables.
Check whether power cables of indoor and ODUs are installed according to vendor requirements and
whether cable connectors are reliably connected. Except the connection part of patch panels, wire
exposure is not allowed on any connection part of power cables.
3) Check the power capacity required for the unit.
The air conditioning unit works at a current much larger than the rated current (the working current
changes in a large scope in different conditions). The power grid provides unstable voltages and the line
power factor decreases. Therefore, the power capacity should not be less than the maximum power of
the unit.
4) Check air switches and fuse links for their models and using methods.
a. Commercial air conditioning units must be installed with independent air switches, fuse links, and
similar protectors. Reasonable models and using methods should be selected for air switches and fuse
links.
Remarks:
a1. Air switches work for overload and short-circuit protection. Air switches provide a less breaking
current than fuse links and air switches react more slowly than fuse links. The advantage of air switches
is that they can be manually reset after a protection action.
a2. Fuse links only work for short-circuit protection. They provide a large breaking current and act slowly.
However, fuses must be replaced after a protection action.
b. Select air switch models according to the power cable diameter and air switch specifications. In
general, the rated current of air switches should be larger than or equal to the load current calculated
based on the line, and less than or equal to the persistent current rating allowed by the conductor.
5) Check components in the electric box.
In the case of unit power-off, visually check whether any component in the electric box drops during
transportation. Then, check whether any component or cable is loose or drops by hand. For a
large-scale unit, power cable terminals of the patch panel and cable terminals connected with
connectors must be tightened with a sleeve spanner or screwdriver, and tightened once more after two
months of normal operation. Auxiliary contacts of AC connectors cannot be removed because they have
been debugged upon factory departure.
6) Check the input power.
a. Power consistency check: Measure the power supply to be connected with the air conditioning unit for
its voltage, frequency, three-phase voltage unbalance factor, and frequency offset. Specifications of the
power supply should be consistent with power specifications displayed on the unit nameplate. The
fluctuation range of voltage should be within ±10%.