System Protection CH 1

Question 1

the coordination and application of key equipment so that it functions in a manner that ensures the reliability and safety of a system

Answer 1

System protection

Question 2

a certain application and coordination of
equipment for a specific portion of the system

Answer 2

protection scheme

Question 3

the proper operation of several pieces of equipment together and is the key to effective system protection.

Answer 3

Coordination

Question 4

the quantity of electrical component
that has to be measured for pieces of equipment that interrupt the flow of current.

Answer 4

time current
characteristics

Question 5

the graphic representation of time current
characteristics of different protective devices and how they relate to each
other.

Answer 5

Protection curves

Question 6

The engineering done to design the protection for a system or a circuit

Answer 6

coordination study

Question 7

high voltage, low voltage, excessive current,
incorrect frequency, and/or single-phasing could cause damage to customer
equipment.

Answer 7

Abnormal conditions

Question 8

a condition where a short circuit has occurred somewhere on the system, either on a line or piece of equipment.

Answer 8

Faulted Conditions

Question 9

These faults are sustained and cannot be cleared without some type of repair.

Answer 9

Permanent Faults

Question 10

These faults can be cleared by momentarily de-energizing the line.

Answer 10

Temporary Faults

Question 11

What are the types of ground faults?

Answer 11

Phase-to-Ground, Phase-to-Phase, Three-Phase, & Two-phase-to-Ground and Three-Phase-to-Ground faults

Question 12

occur when a phase conductor makes contact with ground.

Answer 12

Phase-to-ground faults

Question 13

occur when two phases of a circuit make contact.

Answer 13

Phase-to-Phase fault

Question 14

occur when the neutral breaks and whips around the conductors or when the structure falls to the ground

Answer 14

Two-phase-to-Ground and Three-Phase-to-Ground fault

Question 15

occurs when all three phases are faulted together, but they aren’t making contact with ground.

Answer 15

Three-Phase Fault

Question 16

What are the basic objectives for system protection?

Answer 16

Protect the general public by reducing exposure to live conductors. Protect utility personnel who may be working on the lines and equipment. Minimize damage to lines and equipment. Minimize the number of customers out of service and the time they are out of service. Minimize damage to any customer’s equipment by maintaining the proper voltage and frequency. Maintain the reliability of the system by minimizing the potential for a fault condition to affect additional lines and equipment. (This objective relates more to the transmission system.)

Question 17

Is the most common type of fault permanent or temporary?

Answer 17

temporary

Question 18

What are the basic rules of coordination?

Answer 18

1. For permanent faults, remove only the smallest portion of system that contains the fault. 2. For temporary faults, give all faults a chance to be temporary by providing a reclosing operation for a fault anywhere on the system.