VSD Series Drives User Manual Powered by Eaton Technology
15-22 For more information visit: www.johnsoncontrols.com LIT-1201828
November 2009
Figure 15-17: Motor Temperature Calculation
710 Motor Thermal Protection: 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 stage
has reached 63% of its final value.
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
in minutes is equal to 2xt6. If the drive is in stop stage, the time constant is internally
increased to three times the set parameter value. Cooling in the stop stage is based on
convection and the time constant is increased. See Figure 15-17.
711 Motor Thermal Protection: Motor Duty Cycle
Define how much of the nominal motor load is applied. The value can be set to
0% – 100%.
712 Stall Protection
0 No response
1 Warning
2 Fault, stop mode after fault according to ID402
3 Fault, stop mode after fault always by coasting
Setting the parameter to 0 will deactivate the protection and reset the stall time
counter.
Motor
Current
I/I
T
105%
Trip Area
Fault/Warning
ID707
Time Constant T*
Motor Temperature = (I/I
T
)
2
x (1 - e
-t/T
)
*Changes by Motor Size and
Adjusted with ID710
Motor Temperature
Time
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