Evidence shall show that knowledge has been acquired of safe working practices and finding and rectifying faults in appliance motors and associated controls. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-EJ153A Refrigeration and air conditioning motors and associated controls Evidence shall show an understanding of refrigeration and air conditioning motors and associated controls, applying safe working practices and relevant Standards, Codes and Regulations to an extent indicated by the following aspects: T1 Three phase induction motors Revise the principles of electromagnetism Phase sequence Three phase induction motor action Induction motor construction stator construction rotor construction Speed and slip Line and phase voltages Terminal block markings Motor nameplate details Motor rating Star and Delta connections Electrical isolation Electrical testing and fault finding Rotation reversal Maintenance requirements T2 Three phase motor starters Types of three phase induction motor starters Direct-on-line motor starters characteristics, applications and limitations line and control voltages connection, testing and fault finding Other motor starters – characteristics, applications and limitations Star-delta Auto-transformer Part winding Solid State (soft start) T3 Three phase motor protection devices Motor protection Motor protection devices star point overloads Types of protection devices fuses and circuit breakers thermal overload magnetic overload under voltage and overvoltage relays electronic motor protection Isolation devices Timers Environmental protection Fault finding in three phase motor installations Motor circuit faults T4 Split phase, single phase motors and starters Split phase single phase motors Development of starting torque in split phase induction motors Winding characteristics Construction details Starting centrifugal switch current coil relay solid state relay Characteristics of a split phase motor advantages disadvantage rating speed reversal Testing and fault finding T5 Capacitor and shaded pole, single phase motor and starters Capacitor start motors Characteristics Switching mechanism Applications Motor reversal Capacitor start/capacitor run motors Characteristics Switching mechanism Applications Motor reversal Permanently split capacitor motors Characteristics Applications Motor reversal Capacitors Shaded pole induction motors Advantages Disadvantages Reversal Applications Motor faults and fault finding Capacitor start types Shaded pole motor type T6 Series universal, single phase motors Basic motor principles Commutation Electromagnet field system Reversal Supply types, a.c. /d.c. Construction Characteristics Applications Reversal Faults Synchronous motor T7 Single phase motor protection devices Motor protection Environmental Overheating Thermal overload relay Thermal disc overload Internal overload Protection against open circuit, under voltage and automatic restarting Testing and fault finding T8 Single phase motor speed control devices Speed control methods Pole changing method Voltage control method Inverter |