Danfoss VACON 3000 Application Manual page 199

VACON® 3000
Application Guide
7.156 (ID 707) Motor Thermal Time Constant
Location in the menu:
• INU application: P3.9.2.4
Use this parameter to set the motor thermal time constant.
The time constant is the time within which the calculated thermal stage has reached 63% of its final value. The final thermal stage
equals to running the motor continuously with nominal load at nominal speed. The length of the time constant is in relation with
the dimension of the motor. The bigger the motor, the longer the time constant.
In different motors, the motor thermal time constant is different. It also changes between different motor manufacturers. The de-
fault value of the parameter changes from dimension to dimension.
The t6-time is the time in seconds that the motor can safely operate at 6 times the rated current. It is possible that the motor manu-
facturer gives the data with the motor. Use this information to set the time constant parameter. Usually, the motor thermal time
constant in minutes is 2*t6. When the drive is in the STOP state, the time constant is internally increased to 3 times the set parame-
ter value, because the cooling operates based on convection.
I
T
100%
63%
Illustration 38: The motor thermal time constant
A Current
B T = Motor thermal time constant
Danfoss A/S © 2021.09
A
B
Parameter descriptions
t
t
AB319735759636en-000101 / DPD01822 | 199