Temperature; Cooling - Danfoss VLT Refrigeration Drive FC 103 Design Manual

System Integration
condensation is possible due to ambient conditions. Avoid
installation in areas subject to frost.
Alternatively, operating the frequency converter in stand-
by mode (with the unit connected to the mains) reduces
3 3
the risk of condensation. Ensure that the power dissipation
is sufficient to keep the frequency converter circuitry free
of moisture.

3.1.2 Temperature

Minimum and maximum ambient temperature limits are
specified for all frequency converters. Avoiding extreme
ambient temperatures prolongs the life of the equipment
and maximises overall system reliability. Follow the
recommendations listed for maximum performance and
equipment longevity.
•
Although the frequency converter can operate at
temperatures down to -10 °C, proper operation at
rated load is only guaranteed at 0 °C or higher.
•
Do not exceed the maximum temperature limit.
•
The lifetime of electronic components decreases
by 50% for every 10 °C when operated above the
design temperature.
•
Even devices with IP54, IP55, or IP66 protection
ratings must adhere to the specified ambient
temperature ranges.
•
Extra air conditioning of the enclosure or instal-
lation site may be required.

3.1.3 Cooling

Frequency converters dissipate power in the form of heat.
The following recommendations are necessary for effective
cooling of the units.
•
Maximum air temperature to enter enclosure
must never exceed 40 °C (104 °F).
•
Day/night average temperature must not exceed
35 °C (95 °F).
•
Mount the unit to allow free cooling airflow
through the cooling fins. See
chapter 3.7.1 Clearance for correct mounting
clearances.
•
Provide minimum front and rear clearance
requirements for cooling airflow. See the
operating instructions for proper installation
requirements.
36
®
VLT Refrigeration Drive FC 103
3.1.3.1 Fans
The frequency converter has built-in fans to ensure
optimum cooling. The main fan forces the air flow along
the cooling fins on the heat sink, ensuring cooling of the
internal air. Some power sizes have a small secondary fan
close to the control card, ensuring that the internal air is
circulated to avoid hot spots.
The internal temperature in the frequency converter
controls the main fan. The speed gradually increases along
with temperature, reducing noise and energy consumption
when the need is low, and ensuring maximum cooling
when the need is there. The fan control can be adapted
via parameter 14-52 Fan Control to accommodate any
application, also to protect against negative effects of
cooling in cold climates. In case of overtemperature inside
the frequency converter, it derates the switching frequency
and pattern. See chapter 5.1 Derating for more info.
3.1.3.2 Calculation of Airflow Required for
The airflow required to cool a frequency converter, or
multiple frequency converters in 1 enclosure, can be
calculated as follows:
1.
2.
3.
4.
The calculation is expressed by the formula:
V =
where
V = airflow in m
f = factor in m
Q = heat to be transferred in W
= temperature inside the enclosure in °C
T
i
= ambient temperature in °C
T
A
f = cp x ρ (specific heat of air x density of air)
Danfoss A/S © 08/2015 All rights reserved.
Cooling the Frequency Converter
Determine the power loss at maximum output for
all frequency converters from data tables in
chapter 7 Specifications.
Add power loss values of all frequency converters
that can operate at same time. The calculated
sum is the heat Q to be transferred. Multiply the
result with the factor f, read from Table 3.1. For
3
example, f = 3.1 m x K/Wh at sea level.
Determine the highest temperature of the air
entering the enclosure. Subtract this temperature
from the required temperature inside the
enclosure, for example 45 °C (113 °F).
Divide the total from step 2 by the total from
step 3.
f x Q
T − T
i A
3 /h
3
x K/Wh
MG16G202