72
Parameter Descriptions
Honeywell
10
9.9 M
OTOR
COOLING
FACTOR
AT
ZERO
SPEED
The cooling power can be set between 0-150.0% x cooling power at nominal
frequency. See Figure 10.13
.
Figure 10.13: Motor cooling power
9.10 M
OTOR
THERMAL
TIME
CONSTANT
This time can be set between 1 and 200 minutes.
This is the thermal time constant of the motor. The bigger the motor, the bigger
the time constant. The time constant is the time within which the calculated
thermal model has reached 63% of its final value.
The motor thermal time is specific to the motor design and it varies between
different motor manufacturers.
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 2xt6. If the drive is in stop state the
time constant is internally increased to three times the set parameter value.
See also Figure 10.14.
f
f
n
par.9.9=40%
0
I
T
100%
Overload area
Pcooling
