Chapter 11 Electrical Utilities Flashcards Preview

Truck Company Operations Mittendorf 1998 > Chapter 11 Electrical Utilities > Flashcards

Flashcards in Chapter 11 Electrical Utilities Deck (42):
1

What is the definition of high voltage?

Anything over 600 volts

2

What are the four types of lines used to conduct electricity?

Transmission, subtransmission, primary distribution, and secondary distribution

3

What is the pprimary function of a transformer?

Transformers are used either to reduce or increase voltages as necessary.

4

What is the best method to determine the approximate voltage of conductors?

The size of the insulators and the distances between them

5

What are the three primary ways to eliminate the electrical service to a structure?

Depend on local Utility companies, shut off the service, and cut the drip loops

6

Why shouldn't you pull a meter to eliminate the electrical service?

A meter can flash or explode, live line connectors will be exposed, and the meter may have been bypassed

7

What are the three types of main power disconnects?

Fused pullout, circuit breaker, and lever

8

Should suppression personnel enter electrical rooms marked "high voltage" to curtail the flow of electricity?

No. ONly appropriate utility company personnel should enter these areas to curtail the flow of electricity

9

What is the only practical way to ascertain the distribution of electrical power within complex occupancies?

Preplanning with qualified building engineers

10

What is a UPS room, and what are its specific hazards?

Uninterrupted power supply rooms. The hazards are potential acid spills, vapors from charging batteries, and bare bus bars

11

Electricity can be transmitted to municipalities on lines of how many volts?

115,000 volts to 1 million volts

12

Subtransmission lines carry what voltage?

34,500 volts

13

Primary distribution lines carry what voltage?

4,800 volts

14

Secondary distribution lines carry what voltage?

480 volts, 240 volts, 120 volts

15

Why can 4,800 volts be more dangerous than 34,500 volts?

An apparently dead wire can suddently become live when relays automatically set

16

Where can transformers be located? (3)

Above ground on poles
On the ground on concrete pads
Underground in vaults

17

What is considered high voltage and requires marking with "high-voltage" signs

750 volts and above

18

Subtransmission line (34,500 volts) insulators are how long?

12-22 inches

19

Primary distribution line (4,800 volts) insulators are how long?

4-6 inches

20

Secondary distribution line (480, 240, 120 volts) are how long?

2-3 inches

21

Transmission line (115,000 to 1,000,000 volts) insulators can be how long?

4 feet to 14 feet long

22

Where are Subtransmission transformers usually located?

Normally mounted on a platform between poles

23

What is the safest and most effective method to prevent injury from electric shock?

eliminate all electrical service to a structure

24

If it is necesary, how should a meter be removed?

Do not pull outward. pull upward towards the source of supply, then out

25

What is the minimum tools and equipment required when cutting electrical conductors?

Turnouts
Eye protection
Gloves--Rubber or leather
Axe, Wire cutters, hot stick

26

When cutting drip loops, do not cut wires that carry what voltage?

How much wire do you leave?

over 750 volts

At least 6 inches

27

Describe a single-phase triplex service line.

two covered conductors and one bare conductor

28

Describe a three-phase triplex service line.

Three covered conductors and one bare conductor

29

Who's responsible for any electrical hazard?

The first person that sees it

30

What should you always check for after eliminating electrical service to a structure?

Any additional electrical services that may have been overlooked

31

Pad mount transformers can be classified into two classifications? What are they and what are their voltages?

Commercial stations (CS) 4,800 volts

Industrial stations (IS) 34,500 volts

32

What can you check power poles for to determin approx voltage?

High voltage signs
insulator size
Transformer markings

33

After cutting wires, what should you do to the cut wires to prevent other personnel from thinking that the wires are charged?

coil the wires

34

What is step potential?

stepping near or between energized wires on the ground can be electrocuted by this phenomenon

35

Pole-mounted transformers usually provide what?

voltage drop from 34,500 volts to 4,800 volts or
4,800 volts to 480/240/120 volts

36

What voltages can be encountered in street electrical vaults?

4,800 volts to 34,500 volts

37

What shape are the manhole covers that will usually indicate a vault?

square

38

Newer street lights with photoelectric cells are fed by how much voltage?

240 volts

39

Older street lights without photoelectric cells are fed by how many volts?

6,800 volts

40

What voltage do traffic lights operate on?

240 volts

41

Telephone line voltages can range from what?

45 volts to over 100 volts

42

What component of electricity is responsible for injury and death?

amperage