Mechanical Installation (T1 to T9 Models)
‑84‑
The preceding table applies to situations where only one AC drive is mounted in the
cabinet. For a cabinet containing multiple AC drives, calculate the total ventilation
area by adding the ventilation area of each drive according to the table. For example,
if eight T3 models (7.5 kW), two T5 models, and one T9 drives are placed inside the
cabinet, the minimum effective ventilation area of the cabinet air inlet is 8 x 25 + 2 x
60 + 1 x 318 = 638 cm
2
.
If an air filter is installed at the air inlet, the air inlet resistance will rise significantly.
Therefore, the ventilation area of the air inlet must be increased to 1.2 to 1.5 times
the value indicated in the table.
The ventilation area in "
Table 4–2 Minimum effective ventilation area of the cabinet
air inlet
"
on page 83
refers to the actual through‑hole area of an opening. The
ventilation area is calculated opening area x opening rate.
Design of top ventilation
To ensure sufficient heat dissipation of the drive, hot air in the cabinet must be
exhausted to the outside. The passive or active air ventilation mode can be adopted.
● Passive air ventilation (self‑ventilated)
The air flows from bottom to top after being heated. In this mode, the hot air
discharged by the drive is exhausted to outside from the air outlet at the top of the
cabinet.
This might cause accumulated hot air at the top of the cabinet, rising the air
pressure. The air pressure at the cabinet air inlet is low due to suction of the fan
for the drive. Therefore, there is an air pressure difference between the air outlet
and air inlet of the cabinet to form an air flow in the cabinet. The air flow forces
hot air at the air outlet to flow towards the air inlet so that it is absorbed into the
drive again, causing a great temperature rise and an adverse effect on the
performance of the drive.
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