Nidec Unidrive M600 Series - Cubicle Design and Drive Ambient Temperature

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104 Unidrive M Regen Design Guide
Issue Number: 4
Inserting H = 2m and D = 0.6m, obtain the minimum width:
= 2.8 m (111.78 in)
If the enclosure is too large for the space available, it can be made
smaller only by attending to one or all of the following:
• Using a lower PWM switching frequency to reduce the dissipation in
the drives
• Reducing the ambient temperature outside the enclosure, and/or
applying forced-air cooling to the outside of the enclosure
• Reducing the number of drives in the enclosure
• Removing other heat-generating equipment
Calculating the air-flow in a ventilated enclosure
The dimensions of the enclosure are required only for accommodating
the equipment. The equipment is cooled by the forced air flow.
Calculate the minimum required volume of ventilating air from:
Where:
V Air-flow in m³ per hour (1 m³/hr = 0.59 ft³/min)
T
ext
Maximum expected temperature in °C outside the enclosure
T
int
Maximum permissible temperature in °C inside the enclosure
P Power in Watts dissipated by all heat sources in the
enclosure
k Ratio of
Where:
P
0
is the air pressure at sea level
P
I
is the air pressure at the installation
Typically use a factor of 1.2 to 1.3, to allow also for pressure-drops in
dirty air-filters.
Example
To calculate the size of an enclosure for the following:
• Two M600-03400100 (1 x Regen and 1 x motoring drive) models
operating at the Normal Duty rating
• Each drive to operate at 6kHz PWM switching frequency
• External EMC filter (4200-3480) for each drive
• Maximum ambient temperature inside the enclosure: 40 °C
• Maximum ambient temperature outside the enclosure: 30 °C
Dissipation of each drive: 209 W (see Chapter 10 Technical data on
page 276).
Dissipation of external EMC filter: 13 W (max) (see Chapter 10 Technical
data on page 276).
Dissipation of external Regen inductor (4401-0002): 146 W x 1
(see section 10.4.2 Regen filter components for high quality/low
harmonic power supplies on page 294)
Dissipation of external switching frequency filter (4401-0163): 35 W x 1
(see switching frequency filter (4401-0163): 35 W x 1 (see Chapter 10
Technical data on page 276).
Total dissipation: ((209 x 2) + (13 + 146 + 35) = 612 W
Insert the following values:
T
int
40 °C
T
ext
30 °C
k 1.3
P 612 W
Then:
= 238.68 m³/hr (140.82 ft³/min) (1 m³/hr = 0.59 ft³/min)
5.6 Cubicle design and drive ambient
temperature
Drive derating is required for operation in high ambient temperatures
(derating information is provided in Chapter 10 Technical data on
page 276).
Totally enclosing or through panel mounting the drive in either a sealed
cabinet (no airflow) or in a well ventilated cabinet makes a significant
difference on drive cooling.
The chosen method affects the ambient temperature value (T
rate
) which
should be used for any necessary derating to ensure sufficient cooling
for the whole of the drive.
The ambient temperature for the four different combinations is defined
below:
1. Totally enclosed with no air flow (<2 m/s) over the drive
T
rate
= T
int
+ 5 °C
2. Totally enclosed with air flow (>2 m/s) over the drive
T
rate
= T
int
3. Through panel mounted with no airflow (<2 m/s) over the drive
T
rate
= the greater of T
ext
+5 °C, or T
int
4. Through panel mounted with air flow (>2 m/s) over the drive
T
rate
= the greater of T
ext
or T
int
Where:
T
ext
= Temperature outside the cabinet
T
int
= Temperature inside the cabinet
T
rate
= Temperature used to select current rating from tables in
Chapter 10 Technical data on page 276.
W
9,782 2 2× 0,6×()–
20,6+
-----------------------------------------------------=
V
3kP
T
int
T
ext
–
---------------------------=
P
o
P
l
-------
V
31,3× 612×
40 30–
----------------------------------=
Regen inductors can produce significant losses with a normal
operating temperature in the region of 150 °C dependant
upon the ambient temperature. Location of the Regen
inductors should be considered to prevent damage to heat
sensitive components or create a fire risk.
CAUTION