Cooling; Derating - Danfoss VLT AQUA Drive FC 202 Design Manual

Mechanical Installation Con...

9.5 Cooling

NOTICE
Improper mounting can result in overheating and
reduced performance. For proper mounting, refer to
chapter 9.4 Mounting Configurations.
•
Ensure that top and bottom clearance for air
cooling is provided. Clearance requirement:
225 mm (9 in).
•
Provide sufficient airflow flow rate. See Table 9.2.
•
Consider derating for temperatures starting
between 45 °C (113 °F) and 50 °C (122 °F) and
elevation 1000 m (3300 ft) above sea level. See
chapter 9.6 Derating for detailed information on

derating.

The drive utilizes a back-channel cooling concept that
removes heat sink cooling air. The heat sink cooling air
carries approximately 90% of the heat out of the back
channel of the drive. Redirect the back-channel air from
the panel or room by using:
•
Duct cooling
9 9
Back-channel cooling kits are available to direct
the heat sink cooling air out of the panel when
IP20/Chassis drives are installed in Rittal
enclosures. Use of these kits reduce the heat in
the panel and smaller door fans can be specified.
•
Back-wall cooling
Installing top and base covers to the unit allows
the back-channel cooling air to be ventilated out
of the room.
NOTICE
For E3h and E4h enclosures (IP20/Chassis), at least 1
door fan is required on the enclosure to remove the heat
not contained in the back-channel of the drive. It also
removes any additional losses generated by other
components inside the drive. To select the appropriate
fan size, calculate the total required airflow.
Secure the necessary airflow over the heat sink.
Frame
E1h
E2h
E3h
E4h
Table 9.2 Airflow Rate
9.6.2 Derating for Altitude
The cooling capability of air is decreased at lower air pressure.
70
VLT® AQUA Drive FC 202
Door fan/top fan Heat sink fan
[m 3 /hr (cfm)] [m 3
510 (300) 994 (585)
552 (325) 1053–1206 (620–710)
595 (350) 994 (585)
629 (370) 1053–1206 (620–710)
Danfoss A/S © 05/2017 All rights reserved.
9.6 Derating
Derating is used to reduce output current in certain
situations, which prevents the drive from generating
excessive heat within the enclosure. Consider derating
when any of the following conditions are present:
•
•
•
•
•
•
If these conditions are present, Danfoss recommends
stepping up 1 power size.
9.6.1 Derating for Low-Speed Operation
When a motor is connected to a drive, it is necessary to
check that the cooling of the motor is adequate. The level
of cooling required depends on the load on the motor, the
operating speed, and the length of time.
Constant torque applications
A problem can occur at low RPM values in constant torque
applications. In a constant torque application, a motor can
overheat at low speeds because less cooling air is being
provided by the fan within the motor.
If the motor is run continuously at an RPM value lower
than half of the rated value, the motor must be supplied
with extra air cooling. If extra air cooling cannot be
provided, a motor designed for low RPM/constant torque
applications can be used instead.
Variable (quadratic) torque applications
Extra cooling or derating of the motor is not required in
variable torque applications where the torque is propor-
tional to the square of the speed, and the power is
proportional to the cube of the speed. Centrifugal pumps
and fans are common variable torque applications.
/hr (cfm)]
Low-speed operation.
Low air pressure (operating at high altitudes).
High ambient temperature.
High switching frequency.
Long motor cables.
Cables with a large cross-section.
MG22B102