Air-Insulated Substations (AIS) - Part 1: Bus Conductor Materials

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What is the main material used for bus conductors in air-insulated substations?

Copper

Aluminum (correct)

Steel

Brass

What is the approximate conductivity of aluminum compared to copper?

70-80%

50-60% (correct)

40-50%

60-70%

What effect do larger aluminum conductor diameters have?

Greater conductivity

Reduced sag

More corona (correct)

Less wind and ice loads

For the same ampacity, how does the weight of copper conductors compare to that of aluminum conductors?

Copper conductors weigh twice as much Signup and view all the answers

What can be utilized for outdoor substation buses where they can be easily bent and joined?

Flat bars Signup and view all the answers

What limits the number of bars that can be grouped together for heat dissipation?

Skin and proximity effects Signup and view all the answers

What is the main limitation of using flat bars for conductors?

Corona at higher voltages Signup and view all the answers

What factors are used for the size selection of flexible conductors?

Ampacity, strength, weight, and diameter Signup and view all the answers

What is the usual limit for conductor temperature rise under normal operating conditions?

$30^oC$ Signup and view all the answers

What is the emissivity for heavily weathered aluminum conductors?

0.5 Signup and view all the answers

What is the operating principle of a circuit breaker (CB)?

It maintains uninterrupted current flow Signup and view all the answers

What causes the heat required to ionize the medium and strike an arc between contacts in a circuit breaker?

Small contact area Signup and view all the answers

Which factors are responsible for maintaining an arc between contacts in a circuit breaker?

$P.d.$ between the contacts and ionized particles between contacts Signup and view all the answers

What is the main goal of the high resistance method of arc extinction in circuit breakers?

To rapidly increase arc resistance Signup and view all the answers

What is the purpose of the low resistance or current zero method of arc extinction in circuit breakers?

$To$ $rapidly$ $extinguish$ $the$ $arc$ Signup and view all the answers

What is the main purpose of disconnectors in switchgear installations?

To isolate networks or sections galvanically Signup and view all the answers

What type of disconnectors is suitable for rated voltages of 72.5 kV to 420 kV?

Two-column rotary disconnectors Signup and view all the answers

What is the maximum current that disconnectors are suitable for switching?

$0.5 A$ Signup and view all the answers

What forms a horizontal isolating distance in the open position for two-column rotary disconnectors?

Rotating bases Signup and view all the answers

What is the purpose of the interlocking mechanism in disconnectors?

To prevent contacts from opening at high short-circuit currents Signup and view all the answers

What distinguishes two-column rotary disconnectors from other types?

They have swivel heads with the arms and HV contacts Signup and view all the answers

What is the main function of a pantograph disconnector?

Requiring less space than other designs Signup and view all the answers

For what voltage range is the two-column vertical break disconnector preferred?

170 kV Signup and view all the answers

What is the purpose of the rotating insulator in the two-column vertical break disconnector?

Transmitting actuating force to gearbox Signup and view all the answers

What is the main advantage of three-column rotary disconnectors?

Smaller pole spacings and higher mechanical terminal loads Signup and view all the answers

What is the function of earthing switches in disconnectors?

Locating at the fixed contact system Signup and view all the answers

What is the primary characteristic of the two-column rotary disconnector?

Allowing smaller pole spacings and higher mechanical terminal loads Signup and view all the answers

What is a specific feature of pantograph disconnectors in terms of switch status visibility?

Clear visibility of switch status with vertical isolating distance Signup and view all the answers

At what voltage range does the three-column rotary disconnector type operate?

≥ 145 kV Signup and view all the answers

What are the main components of the pantograph disconnector?

Scissors arms (1), Bearing frame (2), Support insulator (3), Rotating insulator (4), Motor operating mechanism (5) Signup and view all the answers

What is the role of the tie-rod in the two-column vertical break disconnector?

Transmitting actuating force from the mechanism to the contact arm with rotary bearings, rotating insulator and gearbox. Signup and view all the answers