8) This describes the essential skills and knowledge and their level, required for this unit. Evidence shall show that knowledge has been acquired of safe working practices and developing engineering solutions for induction machines and their control problems. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-EG145A Induction machines diagnostics Evidence shall show an understanding of developing engineering solutions for induction motor problems to an extent indicated by the following aspects: T1 Operating principles of polyphase induction motors encompassing: rotating magnetic field torque slip MMF relationships Leakage fluxes T2 Construction of polyphase induction motors encompassing: squirrel cage motors slip-ring motors construction considerations in minimisation of tooth locking T3 Speed-torque relationships in induction motors encompassing: maximum torque torque – slip relationships squirrel cage rotor types power flow in the motors power distribution torque units slip ring rotors T4 Induction motor performance testing encompassing: no-load tests locked rotor tests development of motor equivalent circuit from test results analysis of motor performance using circle diagrams T5 Induction motor starters encompassing: starting requirements type of starters starting torque starting dynamics static friction mechanical loads starting duration T6 Reduced voltage starting encompassing: starting dynamics change over conditions starting duration acceleration curves T7 Speed control of induction motors encompassing: constant torque, constant power concepts torque-flux-voltage relationships rotor resistance control stator impedance control variable frequency control (e.g. PAM, PWM, Flux vector control) T8 Braking of induction motors encompassing: electrical braking systems (plugging, d.c. dynamic, regenerative, capacitor-magnetic) mechanical braking systems (mechanical drum, demag, eddy current) T9 Motor protection encompassing: overload earth fault phase failure T10 Motor selection criteria and RMS rating T11 Induction motor maintenance/repair encompassing: routine maintenance schedules type of repairs (mechanical, electrical) T12 Single phase induction motors encompassing: operating principles (especially RMF) construction types speed-torque relationships testing |