YASKAWA T1000V Technical Manual page 42

2.2 Mechanical Installation
External Heatsink Selection
■
Figure 2.6 shows the heat transfer principle from the drive heatsink plate to the heatsink ambient air.
Figure 2.6
For a given ambient temperature, the heatsink plate temperature must not exceed the maximum allowable value. As the
Rθ and Rθ are essentially fixed, this condition must be satisfied by selecting an appropriate heatsink.
HSP HSP-EHS
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
The heatsink height and width should be close to the drive dimensions. Although the dimensions of a certain heatsink
may match the drive, the thermal resistance may be too high. Instead select a heatsink with a different shape (e.g., longer
fins or more fins) that has an appropriate thermal resistance. Compare the actual mounting conditions with the ones
mentioned for the Rθ
EHS
that ability of the heatsink to dissipate heat may be reduced over time due to the accumulation of dirt along the heatsink
surface.
NOTICE: If the heatsink height and width are much larger than the drive heatsink plate dimensions or if multiple drives are installed on
a single heatsink, it may be necessary to recalculate the thermal resistance value given in the heatsink specifications. Consult the
heatsink manufacturer.
Check the Feasibility of a Given Heatsink
Use the formula below to calculate the actual heatsink plate temperature if the selection of the heatsink is limited due to
certain installation conditions (space available etc.).
If T is smaller than the maximum allowable heatsink plate temperature, then the heatsink can be used. To verify the
HSP
temperature, refer to Checking and Monitoring Heatsink Plate Temperature on page
NOTICE: Due to uneven compound thickness, uneven heat generation across the heatsink plate, or other factors, the actual heatsink
plate temperature (monitored in U4-08) can be slightly different from the calculated value. An oH drive fault may occur if the heatsink
plate temperature exceeds the maximum allowable value.
42
Drive
Heatsink plate
Thermal
compound
External
heatsink
Figure 2.6 Thermal Equivalent Circuit
Rθ =
EHS_max
value in the heatsink specifications, applying reduction factors where necessary. Also remember
T = P
HSP Loss
P
Loss
Heatsink plate temperature T
Heatsink plate thermal resistance Rθ
T
HSP
Thermal resistance between heatsink
plate and external heatsink Rθ
External heatsink thermal resistance Rθ
T
Amb
T
Amb
EHS_max
T - T
(
HSP_max Amb
- Rθ - Rθ
HSP HSP-EHS
P
Loss
.
EHS_max
Rθ + Rθ + Rθ ) + T
HSP HSP-EHS EHS
YASKAWA ELECTRIC SIEP C710606 44B YASKAWA AC Drive T1000V Technical Manual
HSP
HSP
HSP-EHS
EHS
.
)
Amb
40.