electrical

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Author:
Anonymous
ID:
173757
Filename:
electrical
Updated:
2012-09-26 22:19:25
Tags:
electrical
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Description:
for journeyman test
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  1. Resistance of copper?
    12.9 ohms
  2. Resistance of Aluminum?
    21.2 ohms
  3. Neutral load of a 3-wire feeder supplied by a 4-wire 3-phase 120/208v or 277/480v wye-connected system formula.
    Ln= root of ((L1^2 + L2^2) - (L1 x L2))
  4. In a 230/460v dual-rated motor is what voltage when field windings are connected in series?
    Parellel?
    • series-460v
    • parallel-230v
  5. Voltage drop permitted for
    -Branch circuit?
    -Entire system?
    -Feeders?
    • branch- 3%
    • system- 5%
    • feeders- 3%
  6. order of conducters best to worst?
    • silver 105%
    • copper 100%
    • gold 72%
    • aluminum 61%
  7. Difference between
    -Kilowatt (Kw)
    -Kilovolt-ampere (Kva)
    • Kw = 1000 watts
    • indicates the measure of power available for work, indicates real power
    • Kva = 1000watts
    • indicates the measure of apparent power
    • kv=kva when power factor is 1
  8. single phase standard transformer ratings in kva?
    • 1
    • 1.5
    • 2.0
    • 3.0
    • 5.0
    • 7.5
    • 10
    • 15
    • 25
    • 37.5
    • 50
    • 75
    • 100
    • 125
    • Underlined =  also standard 3 phase
  9. def. branch circuit
    The circuit conductors between the final overcurrent device protecting the circuit and the outlets
  10. power supplies wired in
    -parallel?
    -series?
    • parallel- Voltage remains the same, current (amp hour for batteries) increases
    • series- Voltage is added together, current remains the same
  11. Volumes allowence per conductor size?
    18, 16, 14, 12, 10, 8, 6
    • 18- 1.5              in^3
    • 16- 1.75
    • 14- 2.00
    • 12- 2.25
    • 10- 2.5
    • 8- 3.00
    • 6- 5.00
  12. one horsepower = ____watts
    746 watts
  13. When doing a feeder service calculation the load demand factor is?
    • 100% for the first 3kva
    • 35% 3001va-120,000 va
    • 25% 120,001va and up
  14. values of AC?
    • Instantaneous value- value at any given moment ranging from peak to neg peak
    • Peak value- effective value /.707
    •                   - effective value x 1.414
    • Effective value- is DC voltage equivalent
    •  AKA RMS "root mean squared" backwards
  15. Volatge drop formula?
    VD = (2 x K x D x I)/cm

    Voltage drop = 2 x constant x distance x currant / Circular mills
  16. Resister colors?
    • Bad beer rots our young guts but vodka goes well
    • black brown red orange yellow green blue violet gray white
  17. risister values?
    • 1st band - first number
    • 2nd band- 2nd number
    • 3rd band- multiplie
    • 4th band- tolarance 5%-10%
    • 5th band- quality

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