YASKAWA V1000 Installation Manual page 23

◆
External Heatsink Selection
Figure 5 shows the heat transfer principle from the drive heatsink plate to the heatsink
ambient air.
Figure 5
Heatsink plate
Thermal
compound
External
heatsink
For a given ambient temperature the heatsink plate temperature must not exceed the
maximum allowable value. As the Rθ
must be satisfied with proper heatsink selection.
Select an External Heatsink by the Thermal Resistance
■
Use the formula below to calculate the maximum thermal resistance Rθ
Select a heatsink with a smaller thermal resistance than Rθ
width should be close to the drive dimensions. If the selected heatsink has a thermal
resistance that is too high, then choose a heatsink with a different shape (e.g. longer or more
fins). Compare the actual mounting conditions with the ones mentioned for the Rθ
in the heatsink specifications and apply reduction factors if necessary. Also remember that
the heatsink cooling ability can reduce by time due to dirt.
NOTICE: If the heatsink height and width are much larger than the drive heatsink plate dimensions or if
multiple drives are installed on one heatsink, it may be necessary to apply correction factors to the thermal
resistance value given in the heatsink specification. Consult the heatsink manufacturer.
Check the Feasibility of a Given Heatsink
■
If a heatsink is given or the selection is limited by the installation conditions (space available
etc.) use the formula below to calculate the actual heatsink plate temperature.
If T is smaller than the maximum allowable heatsink plate temperature, the selected
HSP
heatsink can be used. For verification of temperature, refer to
Heatsink Plate Temperature on page
YASKAWA ELECTRIC TOBP C710606 21D YASKAWA AC Drive - V1000 Finless Installation Guide
Drive
T
HSP
Figure 6 Thermal Equivalent Circuit
HSP
T
(
HSP_max
Rθ =
EHS_max
P
T = P Rθ
HSP Loss HSP
9.
6 Selecting an External Heatsink
P
Loss
Heatsink plate temperature T
Heatsink plate thermal resistance Rθ
Thermal resistance between heatsink
plate and external heatsink Rθ
External heatsink thermal resistance Rθ
T
Amb
T
Amb
and Rθ are essentially fixed, this condition
HSP-EHS
- T
Amb
- Rθ - Rθ
HSP
Loss
EHS_max
+ Rθ + Rθ
HSP-EHS EHS
HSP
HSP
HSP-EHS
.
EHS_max
)
HSP-EHS
. The heatsink height and
) + T
Amb
Checking and Monitoring
EHS
value
EHS
23