Ch. 10 * (Power Distribution) Flashcards Preview

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Flashcards in Ch. 10 * (Power Distribution) Deck (57)
0

Electric shock can cause ___

Injury and death

1

Matching waveforms

"In phase"

2

Ohm's law

V = IR

3

V =

Voltage in volts

4

I =

Current in amperes

5

R =

Resistance in ohms

6

Inductive reactance

Magnetic field

7

Capacitive reactance

Electric field

8

Voltage and current in phase

Resistive load

9

Current lags voltage

Inductive circuit

10

Current leads voltage

Capacitive load

11

Power bill =

$99

12

Watt-Hours

Watts X 24 hours X 365 days

13

1 Watt = ___ BTU/hour

3.413

14

AWG sizing system has become generally accepted ___

Worldwide

15

AWG sizes represent ___

Number of steps involved in wire drawing process

16

AWG size range

36 - 4/0

17

Conductor sizes larger than 4/0

Circular Mils

18

Solid-state equipment generally cause ___

Harmonics

19

Swell

Increase

20

Lag

Decrease

21

The N in N+1 = ___

Need

22

Voltage regulators adjust ___

Line voltage

23

Rectifier

Battery charger

24

Types of battery cells

Except "zinc oxide"

25

Battery room considerations

Avoid direct sunlight
Avoid heating/cooling
Near eyewash facility

26

Battery clearance

3.28'

27

Optimal battery temperature

77°

28

Cell of choice for communications

Lead-calcium

29

Most common alkaline cell

NiCd

30

Cells can be connected in parallel up to ___ times

5

31

Batteries (def.)

Store energy and chemical form

32

Aluminum and copper

Don't mix

33

Low voltage disconnect (LVD)

Disconnects battery

34

Nominal voltage for telcom in the U.S.

-48v

35

Motor generator

Utility

36

Engine generator

Fuel powered

37

Harmonic filter

Reduces voltage

38

Voltage regulator

Adjust voltage

39

Best 'K' rating for data center

K-20

40

K rating =

Transformer's ability to dissipate heat

41

What causes harmonics

Solid-state equipment

42

Transients surge

Rapid increase

43

Increase in voltage

Swell

44

Decrease in voltage

Sag

45

Horsepower =

Unit of measure for mechanical power

46

12,000 BTU

1 ton of air conditioning

47

Ohm's law formula applies to ___

Direct Current (DC)

48

Distribution system

Delivery of electricity from utility to customer

49

With DC power, a ___ drop is allowable

1 V

50

Available voltages depend on ___

Type of transformer

51

Shielded isolation transformers

20%

52

It is ___ that voice and data equipment utilize Isolated Grounds

Not recommended

53

Output of backup UPS supplies bypass circuit to primary UPS

Isolated redundant

54

Formula to calculate power in W

Not VR
Not I/R squared

55

Difference between real power (in watts) and apparent power (in volt-amperes)

Inductance and capacitance

56

Conducted coupling affects

Output/input signal lines and utility/premises electrical power distribution