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P9.14
Time at nominal current, to reach nominal temperature.
The time constant is the time within which the calculated thermal stage has reached 63% of its
final value. The bigger the frame and/or slower the speed of the motor, the longer the time
constant.
The motor thermal time is specific to the motor design and it varies between different motor
manufacturers. The default value of the parameter varies from size to size.
If the motor's t6-time (t6 is the time in seconds the motor can safely operate at six times the
rated current) is known (given by the motor manufacturer) the time constant parameter can be
set basing on it. As a rule of thumb, the motor thermal time constant in minutes equals to 2*t6.
If the drive is in stop stage the time constant is internally increased to three times the set pa-
rameter value. The cooling in stop stage is based on convection and the time constant is in-
creased.
P9.15
0: No action
1: Warning
2: Fault
Communication lost.
P9.16
0: No action
1: Warning
2: Fault
Impedance on thermistor input (optional board OPTB2) is above fault threshold.
3
M
OTOR THERMAL TIME CONSTANT
Motor temperature
105%
Motor•
current
I/I
T
Motor temperature
Figure 21. Motor temperature calculation.
R
ESPONSE TO FIELDBUS FAULT
T
HERMISTOR FAULT
Trip area
Time constant T *)
Q = (I/I T ) 2 x (1-e -t/T )
*)
Changes by motor size and
adjusted with P9.14
Parameter description
Fault/alarm
P9.11
Time
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