AC

AC

1. FLEMMING RULE

   • RIGHT HAND RULE GENERATORS
     • E=BXLXV
   • LEFT HAND RULE MOTORS
     • F= Bx I x L

2. CIVIL

   • in a inductive circuit
     • I LAGS V BY 90
   • in a capacative circuit
     • I LEADS V BY 90
   • LENZS LAW- the current causes a magnetic field there is 2 electromagnetic forces that reply each other

3. SELF INDUCTANCE

   • IS THE CURRENT THAT INDUCED INTO A CABLE BY ITS OWN MAGNETIC FIELD
     • Lx (l2 -IL ) / t

4. VINPS

   • Vp/vs = Is/ip = np/ns

5. LEVERS

   • F1 X D1 = F2 X D2

6. EFFIENCY

   • INPUT/OUTPUT X 100

7. ACCELARATION

   • DISTANCE/TIME
   • FORCE
     • F=M X A

8. WORK DONE

   • FORCE X DISTANCE

9. POWER

   • WORKDONE/ TIME

10. GRAVITY 9.81 M/S

11. MOTORS

    • TORQUE
      • TENDANCY OF A FORCE TO MOVE AN OBJECT AT A POINT
    • WHEN 2 OR MORE MAGNETIC FIELDS ATTRACT
    • SYNCHRONOUS SPEED - speed of the rotating magnetic field
    • ROTOR SPEED-physical speed of how quick the motor moves
      • The different between rotor and synchronous
        • Per unit slip = ( ns- nr) / ns
        • Percentage slip= (ns-nr) / ns x 100
    • Want you use to flip the polarity in a doc motor commutator (acts as a switch
    • The ballast
      • Limits the lamp operation current
        • Provide the required voltage to start the lamp
    • Current flows into the coils. Causes magnetic field be produced. The bars inside the roster causes emf induced. The electrons start to flow. Creates a magnetic field in the roter . There is 2 magnetic fields, with causes the rotor to spin.

12. BASIC MECHANICS

    • Carbon brushes
      • Softer than copper. Not going to damage anything. Its a conductor . Self lubricating .

13. Enter text here

14. Ns= (rps) = f/p

    • N(rpm)= fx60 / p

15. power factor

    • how to improve power factor?
      • install a capacitor across the load or across a supply
    • ac power
      • to work out apparent power VOLTS X AMPS
      • to work out true power VOLTS X AMPS X POWER FACTOR
      • to work out reactive power SQUARE ROOT TRUE POWER- APPARENT POWER

16. star/ delta

    • 3 phase system, the coils are 120 degress out.
    • RMS VALUE= (0.707 xpeak value)
      • AVERAGE= ( 0.636 x peak value)
    • sine wave
      • frequency = 1 / time period

17. impedance (Z)

    • capacitive reactance (XC)
      • xc+ 1/2x3.142x f x c
      • inductive reactance (XL)
        • XL=2 x 3.142 x f x l
        • when the frequency doubles so does the inductctive reactance

18. power triangle

19. why do we use ac for distribution?

    • can easily transformed from one voltage to another. using transformers. ac produces less arcing and sparking on contacts

20. magnetic flux

    • lines of flux cannot cross
    • magnetic flux density ( B) unit= WB/M SQUARED
    • PARADAYS LAW- when a conductor cuts through or is cut by a magnetic field, an emf is induced within it.

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