UNIT 202

UNIT 202

1. Ac Theory

   • Star Connection
   • Delta Connection

2. Dc Theory

   • Current
     • The Unit is Amperes (A)
   • EMF
     • Unit of EMF is Volts (V)
   • Resistance
     • Measured in OHM'S
       • The Formula Symbol R
     • Resistors in a series circuit
       • R1
         • R2
           • R3
       • RT= R1 + R2 + R3

3. Motors

   • 3 Parts on a 3phrase
     • Stator
     • Electromagnets
       • Rotor
   • single phase motors
   • 3 Phrase motors
   • 3 types of Motors
     • Split Phase
       • Capacitor start/capacitor - run motor
     • Capacitor
   • DC Motors Components
     • Field - Stays still
     • Commutator (Attached to the armature)
       • Armature -moving part
       • Flips Polarity on a DC Motors, acts as a switch
     • Carbon Brush
       • Provide current to the moving part
         • Conducts Elecricity
         • Self Lubricating
       • Soft
     • Series
       • Parallel
       • Compound
   • DC Motor Components
     • Poles
     • Field Windings
     • Armature
     • Commutator
     • Carbon Brushes
   • Synchronous Speed (ns)
     • Speed of the magnetic field in the stator
     • Ns ( rps ) = F/P
     • Ns ( rpm ) = 60 X F / P
     • Nr = Rotor speed
       • Slip = Difference between Ns and Nr
         • Per Unit Slip = Ns - Nr / Ns
         • % Slip = Ns - Nr / Ns x 100

4. Transformers

   • Special Transformers
   • Self inductance
     • Equation for self Inductance : L X ( L2 - L1 ) / T
       • L = Value of Inductance in Henrys
       • T = Time in seconds
       • L1 and L2 = Values of Current
   • Mutual Inductance

5. Prefixs

   • Kilo -> k -> 1x10^3
   • mega -> M -> 1x10^6
   • GIGA -> G -> 1x10^9
   • Terra -> T -> 1x10^12
   • milli -> m -> 1x10-3
   • Micro -> yu -> 1x10-6
   • nano -> n -> 1x10-9
   • pico -> p -> 1x10-12
   • Positive
   • Negative

6. Floresent lighting

   • Ultra-Violet, Unless Phosphorus turns into visible light
     • Electrodes are parts at the end of the lights
     • Gas on the inside
   • The Ballast ( Chalk )
     • Limits The Lamps Operating Current
     • Provide the required voltage to start the lamp
     • Two Types
       • Electromagnetic
       • Electronic