Lenze i700

Lenze · i700 servo inverter · reference manual · DMS 3.0 EN · 06/2016 · TD06 257
8 Monitoring functions
8.4 Monitoring of the motor utilisation (I²xt)
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8.4 Monitoring of the motor utilisation (I²xt)
This monitoring detects the thermal utilisation of the motor by calculating the thermal motor
utilisation from the detected motor currents based on a mathematical model and displaying it in
the object 0x2D4F
(or 0x354F for axis B).
In case of permanent overload and excess of the warning threshold set in the object 0x2D4E
(or
0x354E
for axis B), a warning is output in order that the higher-level Controller is still able to
respond and reduce the motor load or interrupt the operation.
From version 01.04 on, an error response in the object 0x2D50:1
(or 0x3550:1 for axis B) can be
parameterised as well if the disconnection should not or cannot be executed by a higher-level
Controller.
During the calculation, the speed dependence of the permissible motor load and thus of the
permissible current (difference between the standstill current and rated current is taken into
consideration. This is done via object 0x2D4D
(or 0x354D for axis B).
The threshold value for the warning output can be adapted via the following object:
0x2D4E | 0x354E - Motor utilisation (I²xt): Motor overload warning threshold
The current thermal motor utilisation is shown in the following object:
0x2D4F | 0x354F - Motor utilisation (I²xt): Actual utilisation
0x2D50 | 0x3550 - motor utilisation (I²xt): Motor overload error
 Stop!
Monitoring the motor utilisation (I²xt) is not a means for full motor protection!
Since the motor utilisation calculated in the thermal model gets lost after mains
switching, the following operating states cannot be determined correctly:
• Restarting (after mains switching) of a motor that is already very hot.
• Change of the cooling conditions (e.g. cooling air flow interrupted or too warm).
Full motor protection requires additional measures such as the evaluation of
temperature sensors that are located directly in the winding or the use of thermal
contacts.
Setting range (min. value | unit | max. value) Lenze setting
0 % 250 100 %
 Write access  CINH  OSC  P  RX  TX UNSIGNED_16
Display area (min. value | unit | max. value) Initialisation
0 % 250
 Write access  CINH  OSC  P  RX  TX UNSIGNED_16
From version 01.04 onwards
If the disconnection must not or cannot be executed by a higher-level Controller, the operation can be interrupted
by the following parameter setting:
• As a response to the excess of the adjustable error threshold, set "1: Fault" in subindex 1.
• In subindex 2, set the threshold value as error threshold which in case of being exceeded triggers an interruption
of the operation.