insulators Flashcards

1
Q

Conductors on overhead lines are electrically insulated from the ground by either resting on insulators or being ?

A

suspended from insulators

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2
Q

Three materials used for overhead line insulators are porcelain, polymer, and ?

A

glass

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3
Q

If three phases and a neutral are mounted on a crossarm, the neutral can be identified as it is the one mounted on a ? insulator.

A

glass

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4
Q

A combination of dirt and moisture will cause insulators to flash over; ? is/are also a likely cause.

A

lightning

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5
Q

The glaze on a porcelain insulator helps the insulator’s surface shed dirt and bead water.

A

true

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6
Q

Pin-type insulators can be two or more pieces cemented together.

A

true

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7
Q

A one-piece insulator can withstand a higher voltage than a two-piece insulator.

A

false

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8
Q

Hand wire ties or ? ties are used to fasten a conductor on most top tie insulators.

A

preformed

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9
Q

Each disk of a porcelain or glass suspension insulator is rated at ?

A

11 kv

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10
Q

A porcelain suspension insulator uses a ball-and-socket design which puts the insulating material under ? to create strength.

A

compression

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11
Q

One piece porcelain pin-type insulators are used on lines where the voltages are less than ?

A

23 kv

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12
Q

A polymer suspension insulator cannot withstand the tension of deadend conductors.

A

false

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13
Q

Pin insulators are no longer used on transmission lines.

A

true

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14
Q

If a suspension insulator string is made up of 50 kip insulators, the insulator string is able to withstand ? of tension.

A

50,000 lbs

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15
Q

Post insulators are positioned on a pole to support conductors in a vertical or horizontal ? position.

A

cantilevered

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16
Q

Post insulators are most likely to be found when a line is built on a ? or along a highway.

A

narrow right of way

17
Q

When hoisting a long string of insulators, care should be taken not to ? because it can damage the ball, socket, and cotter keys.

A

excessively bend the string

18
Q

Polymer insulators are light weight but do not maintain high dielectric or mechanical strength.

A

false

19
Q

A 240-kilovolt suspension insulator string is likely to have ? porcelain insulators.

A

14

20
Q

A 69-kilovolt suspension insulator string is likely to have ? porcelain insulators.

A

4 or 5

21
Q

The diameter of suspension porcelain insulator disks varies from 3 3/8 to ?

A

11 1/2