I just want to simulate the faults and the simulation of protection against such faults which occur on 3 phase induction motor using MATLAB.
From what I seen on the MATLAB site, you will need a variable to represent Current (Amperes) and Voltage.
1. If one of the phases drop (voltage goes to 0 on one of the phases) the other two phases will draw enormous amounts of current... and normally cause the overcurrent device to trip. >600% of FLA rating on the motor. Overcurrent is usually set to be 125% of the FLA. ('Single phasing') If one of the phases is shorted to ground, the same situation would be experienced.
2. If the motor experiences a 'locked rotor' condition... it will try to draw more than the Overcurrent device typically.
Hope this helps.
125% of FLA is the rated fuse size, if the current on any phase is drawn more than that for more than say .5 sec. The fuse opens. Similar occurance happens with the 'overloads' on the 'motor starter' itself, only it works directly from heat proportional to the current as stated above. Which can be arguably the same reaction (design) of fuses.... every level of 'protection' is directly related to current draw. Does this help?
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