P3.9.2.4 MOTOR THERMAL TIME CONSTANT (ID 707)
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 default 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 manufacturer gives the data with the motor. If you know
the t6 of the motor, you can set the time constant parameter with its help. 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 parameter value, because the cooling
operates based on convection.
PARAMETER DESCRIPTIONS VACON · 287
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