Configuration
7-101
48XX/49XXSHB0399
7.7.3 Overload monitoring for the motor (I
2
¼tmonitoring)
The unit can approximately calculate and monitor the motor temperature. The
calculation of the thermal characteristic is derived for externally ventilated motors.
Stop!
This monitoring does not provide full motor protection. The DC controller resets
the calculated motor temperature by switching the mains. If the connected motor
is already hot and still overloaded, overheating cannot be excluded. Self-ventilated
motors cannot be protected with this monitoring.
For total motor protection, integrate a thermal contact or a PTC thermistor in the
motor. Lenze DC motors are equipped with thermal contacts as standard.
The motor monitoring is set as follows:
1. Enter the thermal time constant under C085.
2. Enter the rated motor current under C088.
3. Select the ”I
2
¼t monitoring” under C119.
4. Activate the ”I
2
¼t monitoring” under C120.
If the motor current exceeds the limit for a long period of time, the fault message
”OC6” occurs and the controller is inhibited.
4900Str085
2.00
1.50
0.29
0.59
1.0
2.0
3.0 4.0
1.00
1.25
t
M
1.75
I
Ar
I
O verload factor =
A
FIG 7-58 I
2
t monitoring
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