Lenze i700

8 Monitoring functions
8.4 Monitoring of the motor utilisation (I²xt)
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Lenze · i700 servo inverter · reference manual · DMS 3.0 EN · 06/2016 · TD06
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Parameter setting of the time constant and the influence of the winding on motors of other
manufacturers
When the influence of the winding is activated, the i²xt monitoring becomes more sensible as if only
the influence of the laminated core would be used for monitoring purposes.
The necessity to activate the influence of the winding rises with the increasing utilisation of the
motor overload capacity. It also rises with applications where the motor is at standstill for longer
periods or cyclically and a load ≥ permanent standstill current is applied.
For determining the values for the thermal time constant, try to get the data from the motor
manufacturer. If this is not possible, you can use the data of a comparable Lenze motor.
Conditions for comparability are similar values in case of the following motor features:
• Square dimensions of the motor (active part)
• Length of the active part (if available)
• Permanent standstill current Io [A_RMS]
• Peak current/overload capacity [A_RMS]
• Copper resistance of the winding at 20 °C [Rphase]
Example:
When the "MCS09F38" Lenze motor is selected from the motor catalogue of the »PLC Designer«m
the following values are displayed:
• Thermal time constant of the winding = 126 s  0x2D4C:1
(or 0x354C:1 for axis B)
• Influence of the winding = 27 %  0x2D4C:3
(or 0x354C:3 for axis B)
Speed-dependent evaluation of the motor current
By selecting a characteristic, the permissible motor current is evaluated depending on speed for
calculating the thermal motor utilisation. For this purpose, up to four operating points on the S1
characteristic of a motor can be used.
• The S1 characteristic can be found in the technical data sheet/catalogue of the respective
motor.
• The representation in the objects /characteristic is carried out as relative values with reference
to rated values.
Motor features Data of the third-party
motor
Data of a comparable Lenze motor (from motor
catalogue)
Square dimension 95 mm MCS09xxx = 89 mm
Standstill current 2.2 A MCS09F38 = 3.0 A
Peak current 7.3 A MCS09F38 = 15 A
Phase resistance 5.1 Ohm MCS09F38 = 5.2 Ohm
 Note!
When you select a Lenze motor from the catalogue and transfer its parameters to the
servo inverter, a typical characteristic is automatically set for the motor selected. A
deviating parameterisation is only required if the motor is actuated in ambient
conditions demanding a general derating. Example: Use in site altitudes > 1000 m.
In case of motors of other manufacturers, the operating points have to be parameterised
based on the data sheet information.