3. Motor protection : divided into :
" Unfavorable operating conditions “
Faulty conditions
System disturbances and switching surges (for HT
motors)
4. 1 - "Unfavorable operating conditions “
- Causes lead to high temperature:
1- mechanical over load
2-Under voltage
3- Reverse Rotation
4-Harmonic effects
5- Voltage unbalance
5. 2- Fault conditions:
-Sc between 2 phases
-fault Earth fault
-Stalling of Rotor
- Prolonged starting time
- Increase start & stop for motor times
- Single phasing condition
6. Small and medium-sized LT motors:
1- Protection against Over Load :
