I 2 T Monitoring - HEIDENHAIN iTNC 530 Service Manual

2
9.3.8 I t Monitoring
The actual motor current is limited to either the maximum current of the power module, or the
maximum motor current, whichever is lower. The values result from the type of power module
and type of motor, and are saved in the motor or power module table.
In addition the I
The temperature rise of motor and power module is proportional to the square of the current
consumed. Since heat removal may be non-uniform during standstill or slow movement of the
motor, the monitoring distinguishes two different ranges: This is the purpose of the F-AC (Cutoff
frequency for T-AC [Hz]) in the motor-and-power-module table. Above this frequency the T-AC
(Thermal time constant AC [s]) applies; below this frequency the T-DC (Thermal time constant
DC [s]) takes effect. The T-AC and T-DC input values mark that point of the temperature curve
at which 63 % of the maximum temperature are reached. This defines a temperature model of
the motor or power stage.
T [°C]
100 %
63 %
With the aid of this temperature model, a mean current value is permanently calculated. If this
calculated mean current value exceeds the rated current (for motors, plus MP2302.x and
additionally for power modules MP2304.x), the I
case, you should reduce the machining feed rate in the PLC program. If the calculated mean
current value is more than 1.1-fold of the rated current, (for motors, plus MP2302.x) an error
message appears; the drives are not switched off.


9 – 66
2
t monitoring for the power module and for the motor is executed:
T-AC
T-DC
MP2302.x contains a reference value for I
of the rated current of the motor (1 = rated current of the motor). If you enter zero, the I
monitoring for the motor (not for the power module) is switched off.
MP2304.x contains a reference value for I
is a factor of the rated current of the power module (1 = rated current of the power module).
2
If you enter zero, the I t monitoring for the power module (not for the motor) is switched off.
Note
In the integrated oscilloscope you can display the current values of the I
motor and power module, as well as the current load of the drive.
Temperature curve via E-function
2
t monitoring (module 9160) responds. In this
2
t monitoring of the motor. The input value is a factor
2
t monitoring of the power module. The input value
HEIDENHAIN Service Manual iTNC 530
t [s]
2
t
2
t monitoring of the