ABB ACS260-04 Series, User Manual

Page: 20 / 98

20 Mechanical installation
Heatsink Capacity Calculation
ACS260 Units are designed to be mounted to a metallic, heat conducting surface in
order to maintain the unit operating temperature. Thermostrate or heatsink compound
must be added to ensure optimal heat transfer and minimum thermal resistance.
In order to calculate the necessary heatsink requirement, the following formula can
be used. Example values based on typical conditions are given in the table below.
• Determine the maximum ambient air temperature around the heatsink, T
AMB
• Select the desired PWM operating frequency from the available options in
Parameter 2606.
• From the table below, determine the maximum permissible heatsink temperature,
T
MAX
• Determine the maximum allowed Temperature Rise
• T
RISE
= T
MAX
- T
AMB
• Calculate the motor absorbed electrical power, P
MOT
, based on the motor rated
voltage, current and efficiency
•
P
MOT
= √ 3 * Rated Voltage * Rated Current * Power Factor * Efficiency
• Calculate the losses in the drive, P
LOSS
, based on the required motor power
• P
LOSS
= P
MOT
* (1 - Drive Efficiency)
• Typical drive efficiency values are shown in the table below for each available
effective switching frequency
• Calculate the required heatsink maximum thermal resistance R
MAX
• R
MAX =
T
RISE /
P
LOSS
Maximum Permissible Heatsink Temperature
The maximum permissible heatsink temperature allowed for the ACS260 drive is
linked to the desired effective switching frequency selected by parameter 2606. In
order to maintain operation at a certain switching frequency, the heatsink temperature
must be maintained below the threshold level shown in the table below. If the tem-
perature exceeds the threshold, the switching frequency will automatically reduce.
Note: Switching frequency may be automatically reduced under certain operating
conditions, refer to section Automatic Switching Frequency Reduction on page 88 for
further information.
Temperature Threshold Action
65
℃ Auto reduce from 32kHz to 24kHz
70
℃ Auto reduce from 24kHz to 16kHz
80
℃ Auto reduce from 16kHz to 12kHz
85
℃ Auto reduce from 12kHz to 8kHz
94
℃ Over temperature trip if 2606 >= 8kHz
97
℃ Over temperature trip if 2606< 8kHz
ACS260-04.book Page 20 Thursday, December 24, 2020 4:33 PM