Ch. 10 - Power Distribution.csv Flashcards Preview

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Flashcards in Ch. 10 - Power Distribution.csv Deck (70):
2

Measure amplitude

RMS
(10-2)

3

Frequency of electric power =

50 or 60 Hz
(10-3)

4

Two wave forms that match each other in electrical degrees are ________

In Phase
(not out of phase, in sync, etc..)
(10-4)

5

Electrical systems between serving utility & customer site is:

Distribution system
(10-7)

6

V = IR

Ohm's Law
(test)
(10-9)

7

V= I= R=

V= Voltage
I = Amperes
R = Resistance
(10-9)

8

Formula for Ohm's Law always applies to _____.

DC
(test)
(10-10)

9

Z =

Impedance
(test answer)
(10-10)

10

Inductive reactive X =

magnetic field
(10-10)

11

Capacitive reactance X =

electrical field
(10-10)

12

Voltage & Current in phase =

resistive load
(figure 10.9)
(10-11)

13

Current lags voltage =

Inductive circuit
(figure 10.10)
(10-11)

14

Current leads voltage =

Capacitive load
(figure 10.11)
(10-12)

15

Apparant power =

Measured voltage
(10-12)

16

Real power =

Calculation
(10-12)

17

Utility companies charge for power in ________.

Killowatt hours (kwh)
(10-13)

18

One kwh is equal to _________

1000 watt-hours
(10-13)

19

Test question: 1850 watt hours x 24 hours a day x 30 days = 1332.00
1332 x 0.075 = ________

$99 month
(10-13)

20

1 watt = ________ btu/hr

3.413 btu/hr
(10-14)

21

watts x 3.413 =

heat dissipation in BTU
(test)
(10-14)

22

Formula for tons of A/C:

# of watts x 3.413/12000= (answer) tons of A/C
(test)
(10-14)

23

BTU/12000 =

tons of air conditioning
(10-14)

24

AWG accepted =

Worldwide
(10-16)

25

Sizes in the AWG system represent

# of steps
(test)
(10-16)

26

AWG smaller #'s =

larger wires
(10-16)

27

AWG larger #'s =

smaller wires
(10-16)

28

AWG smallest size = ______
largest size = ______

-36 awg
-4/0 = 460 mil
(10-16)

29

Circular mills =

4/0 & above
(10-17)

30

Swell =

increase, 05. cycle - 1 minute
(10-20)

31

Sag =

decrease, 0.5 cycle - 1 minute
(10-20)

32

Undervoltage =

decrease, 3600 cycles (1 minute)
(10-20)

33

Harmonics caused =

Solid state equipment
(10-21)

34

Harmonic distortion =

size the neutral conductor to carry 200% of the load
(10-23)

35

K rating tells of the transformer ability to _______

dissipate heat
(10-24)

36

The higher K rating

the better the transformer
(10-24)

37

K-20 =

best for data centers
(10-24)

38

N Tier classification =

need
(test)
(10-31)

39

N-1 =

1 additional heat unit
(10-31)

40

N-2 =

2 additional heat units
(10-31)

41

2N =

2 complete units
(10-31)

42

2 (N+1) =

2 complete (N+1) units
(10-31)

43

Voltage regulator =

adjusts voltage
(10-39)

44

Harmonic filters =

reduce voltage
(10-39)

45

Motor generator =

utility to drive a motor
(no fuel)
(10-39)

46

Engine powered generator =

fuel-powered
(10-40)

47

Rectifier/Charger =

AC to DC
Charges the battery
(test)
(10-55)

48

Inverters =

DC to AC
(test)
(10-55)

49

Low voltage disconnect (LVD)

used to disconnect the battery
(10-56)

50

Batteries do not store electricity, they store ________

energy
(10-66)

51

Three main types of battery cells

-alkaline
-flooded
-VRLA
(not zinc oxide)
(10-66)

52

Cells can be connected in _______ to increase battey capacity.

parallel
(test)
(10-66)

53

Most common alkaline cell =

NiCd cell
(10-67)

54

Battey cell of choice =

lead-calcium
(10-67)

55

Battery room ventiliation

min. of four changes per hour
(10-67)

56

What info. is needed for battery cell sizing?

-Direct current required
-Direct current input window
-Operating temp of batt.
-Batt. backup time
(not: fit)
(10-70)

57

How many batteries in parallel recommended?

5
(test)
(10-73)

58

Battery temperature =

77ºF
(test)
(10-73)

59

Battery life decreased 50% for each _____ above optimum operating temp.

50ºF
(10-73)

60

Avoid exposing batteries =

-direct sunlight
-adjacent to heating/cooling
(10-75)

61

Floodcell battery =

Eye wash facility
(10-75)

62

The harmonics of the sine wave are _____of the_____frequency.

Multiples, basic
(10-21)

63

A(n) ____ UPS topology is usually reserved for extremely large critical facilities.

ring bus
(10-52)

64

Shielded isolation transformers provide added level of protection for sensitive & critical equipment & are preferred over standard isolation transformers where the total load is made up of more than ____% of nonlinear type equipment.

20%
(10-37)

65

In power distribution, feeder and branch circuit conductors should be sized for:

the non-continuous load +125% of the continuous load.
(10-23)

66

An isolation transformer is a transformer that:

has no electrical connection between the primary and secondary.
(10-37)

67

A current that periodically reverses its direction of flow is referred to as:

Alternating current
(10-2)

68

In most ac circuits, there is a reactive component that causes the current to ______ the voltage waveform.

lead or lag
(10-11)

69

The difference between real power (in watts) and apparent power (in volt-amperes) required by the load in an ac circuit is caused by:

Inductance and Capacitance
(10-9)

70

What is the equation used to calculate horsepower (HP) for two-phase power?

HP = V x I x efficiency x power factor x 2 / 746
(10-14)

71

"Maintenance-free" cell is another term used to describe a _______ battery cell.

Valve-regulated lead-acid
(10-66)