€h 10 - Power Distribution Flashcards

1
Q

10-1 Power Distribution

Electrical shock =

A

Cause of injury and death

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2
Q

10-4 Phase difference:

Two waveforms match each other in electrical degrees =

A

“In phase”

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3
Q

10-7 Distribution

Serving utility and the customer’s site =

A

Distribution system

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4
Q

10-9 Ohm’s Law

V =

(2)

A

* Voltage

* IR

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5
Q

10-9 ohms law

I =

(2)

A

* current in amperes

* V/R

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6
Q

10-9 ohms law

R =

(2)

A

* resistance in ohms

* V/I

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7
Q

10-9 ohms law

Formulas to calculate power in W =

A

Except W = RV, does not belong

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8
Q

10-10 ohms law

Ohms law always applies =

A

(dc)

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9
Q

10-10 ohms law

When (V) and (I) are known =

A

Z = sqrt of V/I

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10
Q

10-10 ohms law

When (R) and reactance (X) are known =

A

Z = sqrt of (R^2 + X^2)

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11
Q

10-10 ohms law

When (R), inductive reactance (XL), and capacitive reactance (XC) are known =

A

Z = sqrt of {R^2 + [X (L) - X (C)]^2}

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12
Q

10-10

Inductive reactance =

A

Magnetic

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13
Q

10-10

capacitive reactance =

A

Electric

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14
Q

Fig 10.9

A

Resistive load

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15
Q

Fig 10.10

A

Inductive circuit

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16
Q

Fig 10.11

A

Capacitive load

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17
Q

10-13 watt hours

18,500 kWh x 24hrs x 30days = 1332.00 kWh

Cost per usage = $0.075

A

1332.00 kWh x $0.075 = $99

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18
Q

10-13 watt hours

2,000 W x 24 hrs x 365days = 17,520,00 watt-hours or kWh

Cost per usage = $0.08 per kWh

A

$0.08 x 17,520 kWh = $1,401.60

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19
Q

10-14 Heat

One watt is equal to =

A

3.413 Btu/hr

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20
Q

10-14 Heat

Watts x 3.413 =

A

Heat dissipated in Btu

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21
Q

10-14 Heat

Btu/12,000 =

A

Tons of air conditioning required to maintain ambient temperature

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22
Q

10-14

Horsepower =

A

Unit of mechanical power

23
Q

10-16

AWG =

(2)

A

* American wire gauge

* accepted world wide

24
Q

10-16 AWG numbering system

Sizes in the AWG =

(3)

A

* Number of steps

* smaller # = larger wire

* larger # = smaller wire

25
Q

10-16 solid conductor range

AWG range =

A

36 AWG to 4/0

26
Q

10-17

circular mils =

A

Larger than 4/0

27
Q

10-20 voltage and current fluctuations

Transients/Surge =

A

Rapid increase

28
Q

10-20 voltage and current fluctuations

Swell =

A

Increase .05 cycles to one minute

29
Q

10-20 voltage and current fluctuations

Sag =

A

Decrease 0.5 cycles up to one minute

30
Q

10-20 voltage and current fluctuations

Interruption =

A

Total absence

31
Q

10-21 ac voltage quality problems

Solid-state equipment =

A

Cause harmonics

32
Q

10-22 isolated ground (IG)

IG receptacles =

A

Orange triangle

33
Q

10-24 oversized transformers

K-rating =

(2)

A

* Transformer’s ability to safely dissipate heat

* Higher k-rating the better the transformer

34
Q

10-31 tier classification N-Base requirement

(N) =

A

Need, or no redundancy

35
Q

10-39 devices that filter/regulate utility lines

Voltage regulators =

A

Adjust the line voltage

36
Q

10-39 devices that filter/regulate utility lines

Harmonic filters =

A

Reduce voltage

37
Q

10-39 generator equipment

Motor generators =

A

Using the utility to drive a motor

38
Q

10-39 generator equipment

Engine generators =

A

Futile-powered engine

39
Q

10-53 direct current (dc) power

Telecommunications the nominal operating voltage =

A

U.S. is -48V

40
Q

10-53 direct current (dc) power

Cellular radio the nominal operating voltage =

A

+24V

41
Q

10-55 dc power

Rectifier/charger =

A

Charges the battery

42
Q

10-56 dc power

LVD =

(2)

A

* low-voltage disconnect

* disconnect the battery

43
Q

10-65 installation of (dc) systems

Terminating - do not mix aluminum =

A

Copper cable

44
Q

10-66

Batteries =

A

Store energy

45
Q

10-66 Batteries

Three main types of batteries =

A

* alkaline

* flooded

* valve regulated

* except zinc oxide, does not belong

46
Q

10-66 cells

Cells can be connected in parallel =

A

Increase battery capacity, 5 times

47
Q

10-67 alkaline cells

Common type of alkaline cell =

A

NiCd cell

48
Q

10-67 cells

lead-acid cells =

A

Cell of choice

49
Q

10-67 cells

Gases =

A

A min. of four changes of room air per hour

50
Q

10-73 parallel cells

Five parallel =

A

Not recommended

51
Q

10-73 temperature

Operating temperature of battery =

A

77 degrees

52
Q

10-74

Battery clearance =

A

3.28ft

53
Q

10–75 battery room considerations

Avoid =

A

* exposing the battery plant to direct sunlight

* placing the battery adjacent heating or cooling sources