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Safety
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Introduction
Information
Information
configuration
Calculation of temperature rise in enclosure
Inputs
Table 5-2
Example data
Output sharing choke loss under single unit (L2)
Total loss of single drive (Uni SPMC + SPMD)
Number of drives in enclosure
Width of enclosure
Depth of enclosure
Open area of roof vent (outlet)
Open area of inlet vent
External ambient
Altitude derate factor (Cf x Df)
For this example it is assumed the drive is in an altitude below 1000m
and the enclosure it is mounted in has input and output ventilation.
Calculate open area % of venting and recirculation factor
Open area of roof + open area of inlet x 100
Open area of venting %
=
-------------------------------------------------------------------------------------------------------------------------- -
= (0.27 + 0.15) x 100 / (2 x 0.8 x 0.5)
= 52.5%
From Figure 5-33 the re-circulation factor = 0.76.
Figure 5-33 Recirculation factor
1.2
1
0.8
0.6
0.4
0.2
0
0
20
40
This is an approximation to the amount of air that is re-circulated within
the enclosure due to inlet and outlet venting restrictions. The factor has a
safety factor built in to it to ensure a safe result. The factor has been
calculated using CFD software, testing the amount of heat flow back into
the drive when different vent restrictions are given. The factor can also
be applied to an SPMA and separated SPMD.
Calculate loss which affects the drive inlet air temperature
Loss affecting drive temperature (Pr) = Lower choke Loss (Pc) +
(Total loss of single drive (Dp) x Recirculation factor (Rf))
= 250 + (4290 x 0.76)
= 3510 W
NOTE
This is the loss from 1 drive unit only as simulations have shown that
with drives mounted inline and in a symmetric system the losses are
shared equally.
Unidrive SPM User Guide
Issue Number: 3
System
Mechanical
Electrical
Getting
Installation
Installation
Started
2 x cubicle width x cubicle depth
60
80
100
Open area (%)
www.controltechniques.com
Basic
Running
Optimization
parameters
the motor
Calculate temperature rise
Table 5-3 Unidrive SPM air flow rates
Modules
250W
SPMA (All)
4290W
SPMD 1201 to 1204, SPMD1401/2,
2
SPMD1601/2
0.8m
SPMD1403/4, SPMD 1603/4
0.5m
SPMC/U
3
0.27m
Calculating temperature rise in enclosure
3
0.15m
dT = 3kPr/V
30°C
Where:
1
V = Airflow in m
dT = Temperature rise
Pr = Loss affecting drive temp
k = 1 / Altitude de-rate
Therefore ambient temperature rise (dT):
= (3 x 1 x 3510.4) / 305
= 34.5°C
So,
Ambient temperature inside enclosure = External ambient +
temperature rise = 64.5°C
This shows that with a maximum allowable drive ambient temperature of
40°C, the enclosure will get 24.5°C too hot.
Processing results
Option 1: If the absolute temperature inside the enclosure is still less
than 50°C, select a drive with the correct rating at 50°C.
Option 2: Add more venting, if possible, to reduce the recirculation and
recalculate.
Option 3: Add enclosure fan.
Option 4: Redesign the enclosure so that the drives can be through
panel mounted. This means that most of the heat can escape outside
the main enclosure and the input air into the heat sinks will remain at the
external ambient and not be affected by recirculation. Refer to section
5.7.2 Through-panel mounting on page 44.
NOTE
Heat loss through the front of the drive still needs to be considered.
120
Adding enclosure fan
Calculate required flow rate
•
Fan needs to remove the effect of re-circulation and the added
choke loss.
•
Loss effecting drive temp (Pr) = 3510.4W
•
The above Loss of 3510.4W is for one drive only, so with an
enclosure of 2 units the total loss to remove = 7020.8W
Calculate the temperature rise allowed in the enclosure:
Temperature rise (dT) = (Allowable drive ambient - 5 {safety
= (40 - 5) - 30
= 5°C
Then using:
V = 3kPr/ (dT)
Flow rate required to remove loss = (3x1x7020.8) / 5
= 4212.5 m
Calculate back pressure on fan
Open area of venting %
SMARTCARD
Onboard
Advanced
Technical
operation
PLC
parameters
Data
Flow rate (m3/hr)
3
/hr (Unidrive SPMD1404 flow rate = 305)
factor}) - External ambient
3
/hr
Open area of roof + open area of inlet x 100
-------------------------------------------------------------------------------------------------------------------------- -
=
2 x cubicle width x cubicle depth
UL Listing
Diagnostics
Information
250
250
305
200
53
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