GE Industrial Solutions QW030xx DUAL Series - Manual (Page 11)

Lineage Power 11
Data Sheet
October 2008 18 Vdc to 36 Vdc or 36 Vdc to 75 Vdc Inputs
QW030xx DUAL Series Power Modules: dc-dc Converters;
Thermal Considerations
(continued)
Heat Transfer Without Heat Sinks
Increasing airflow over the module enhances the heat
transfer via convection. Figures 8 and 10 show the
maximum power that can be dissipated by the module
without exceeding the maximum case temperature ver-
sus local ambient temperature (T
A
) for natural convec-
tion through 3 m/s (600 ft./min.).
Systems in which these power modules may be used
typically generate natural convection airflow rates of
0.3 ms
–1 (60 ft./min.) due to other heat-dissipating com-
ponents in the system. Therefore, the natural convec-
tion condition represents airflow rates of up to 0.3 ms
–1
(60 ft./min.). Use of Figure 8 is shown in the following
example.
Example
What is the minimum airflow necessary for a
QW030BK operating at V
I
= 48 V, an output current of
1.5 A, each and a maximum ambient temperature of 89
°C?
Solution
Given: V
I
= 48 V
I
O1
= 1.5 A, I
O2
= 1.5 A
T
A
= 89 °C
Determine P
D
(Use Figure 9):
P
D
= 4.5 W
Determine airflow (v) (Use Figure 8):
v = 3.0 m/s (600 ft./min.)
1-0206
Figure 8. QW030BK POWER DERATING CURVE
1-0204
Figure 9. QW030BK Power dissipation With
Balanced Loads
1-0205
Figure 10. QW030BK Power Dissipation with
Unbalanced Loads with Io1 = 0.5 A
LOCAL AMBIENT TEMPERATURE, T A ( C)
PO
WER DISSIP
A
TION, P
D
(W)
40 50 60 70 80 90 110 100
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
3.0 m/s (600 ft./min.)
2.0 m/s (400 ft./min.)
1.0 m/s (200 ft./min.)
NATURAL CONVECTION
MAX CASE TEMP.
OUTPUT CURRENT, I O 1 = I O 2 (A)
PO
WER DISSIP
A
TION, P
D
(W)
0 0.5 1 1.5 2 2.5
6
5
4
3
2
1
0
V I = 48 V
V I = 36 V
V I = 75 V
OUTPUT CURRENT, I O 2 (A)
PO
WER DISSIP
A
TION, P
D
(W)
0 0.5 1 1.5 2 2.5
6
5
4
3
2
1
V I = 48 V
V I = 36 V
V I = 75 V
3.0