I2T Motor Overload Protection
The energy dissipated by a motor is proportional to the square of the current circulating through it and the total time the current flows. The nominal current is the current that a motor can sustain continuously without exceeding its thermal capacity. Any current above the nominal current can create an accumulation of thermal energy in the motor. If this process of accumulating thermal energy exceeds the cooling motor's ability to dissipate it, the system is bound to reach its thermal limits, and permanent damage to the motor.
The I2T (defined in Ampere2 per second) indicates the excess of thermal energy and is an indirect magnitude proportional to the energy dissipated.
The I2T protection is a control mechanism which ensures that the integral of the power dissipated by the motor in the form of thermal energy does not exceed its thermal limits. Under nominal current value, the motor can work continuously but once actual motor current crosses the motor nominal current, the algorithm starts to integrate the excess of thermal energy.
The parameters used for I2T control algorithm are:
I2T_Current_Limit = [ (I2T_Peak_Current)2 - (Nominal_Current)2 ] · I2T_TMax_Peak_Current
I2T_Current_Actual += [ (Current_Actual_Value)2 - ( Nominal_Current)2 ] · Ts (sampling time)
If I2T_Current_Actual > I2T_Current_Limit, the device enters the Fault state.
To enable/disable I2T Protection control mechanism is used Bit#10 of Drive_Working_Settings_Extended object.
For Closed Loop Bit#4 of Drive_Working_Settings object must be set.
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