The following diagram shows a typical characteristic setting for an internally cooled asynchronous machine. For third-party motors the motor manufacturer's specifications apply.
It is necessary to adapt the I2xt characteristic because the factory setting mostly does not exactly map the present motor. For servomotors, it is advisable to set a constant characteristic. The switch-off point defines the permissible current/time area up to switching off 150 % x IN for 120 s. If the I2xt type is set to "THERM(1) = Thermal time constant dependent", all settings apart from the thermal time constant are disabled.
Bild: Motor protection I2xt
Frequency-current data
|
Frequency |
Motor current |
|---|---|
| f0 = 0 Hz | I0 = 30% of IN |
| f1 = 25 Hz | I1 = 80% of IN |
| fN = 50 Hz | IN = 100% |
Tabelle: Frequency-current data
Factory setting
Bild: ASM characteristic factory setting
|
NOTE: The limits are specified in the servocontroller as percentages of the rated quantities (e.g. current, torque, speed,...) of the motor. The defaults relate to 100 % of the rated quantities. |
Calculation of capacity utilization via exponential function with thermal time constant of motor:
Setting of I2t type:
Copyright © LTi DRiVES GmbH, Januar 2013, ID-Nr.: 0842.26B.1-00 DE