Capacitors, Reactors, and Surge
Arresters NWLC Exam Questions &
Answers (Grade A+)
Explain why the arrester diverts the majority of the current from a
fault away from the equipment it is protecting. -
correct answer ✅A properly sized lightening arrester has a slightly
lower resistance to earth than the line insulator or equipment it's
protecting.
What is "leakage" as associated with insulators or lightening
arresters and why can it be a safety hazard? -
correct answer ✅The current that tracks across any insulated
device that is touching an energized source to ground. It may be
enough micro-amps to cause heart fibrillation.
What safety precautions must be taken if you have to open an
arrester ground and the arrester is contacting an energized source?
-
correct answer ✅using rubber gloves, bridge the area to be
opened with a temporary jumper.
List the four classes of lightning arrestors and the levels of voltage
where they are normally applied. -
correct answer ✅Station class: 10,000 KVA and above and on
critical smaller substations above 150KV.
, Capacitors, Reactors, and Surge
Arresters NWLC Exam Questions &
Answers (Grade A+)
Intermediate class: below 10,000 KVA. 3KV-120KV
Distribution class: 42KV
secondary class: 650V
What is "BIL" as it applies to electrical equipment? -
correct answer ✅Basic Impulse Level: the point the equipment
insulation will start to fail under surge conditions.
Briefly explain how a substation ground grid works to assure quick
operation of protective devices. -
correct answer ✅It provides a low-resistance path to earth
What is an OHGW and how does it help protect a substation from
lightening? -
correct answer ✅Over head ground wire (static wire, shield wire):
it conducts lightning strikes safely to earth and away from
substation equipment.
What is "Corona" as associated with electrical equipment? -
correct answer ✅The ionization of the air around energized high-
Arresters NWLC Exam Questions &
Answers (Grade A+)
Explain why the arrester diverts the majority of the current from a
fault away from the equipment it is protecting. -
correct answer ✅A properly sized lightening arrester has a slightly
lower resistance to earth than the line insulator or equipment it's
protecting.
What is "leakage" as associated with insulators or lightening
arresters and why can it be a safety hazard? -
correct answer ✅The current that tracks across any insulated
device that is touching an energized source to ground. It may be
enough micro-amps to cause heart fibrillation.
What safety precautions must be taken if you have to open an
arrester ground and the arrester is contacting an energized source?
-
correct answer ✅using rubber gloves, bridge the area to be
opened with a temporary jumper.
List the four classes of lightning arrestors and the levels of voltage
where they are normally applied. -
correct answer ✅Station class: 10,000 KVA and above and on
critical smaller substations above 150KV.
, Capacitors, Reactors, and Surge
Arresters NWLC Exam Questions &
Answers (Grade A+)
Intermediate class: below 10,000 KVA. 3KV-120KV
Distribution class: 42KV
secondary class: 650V
What is "BIL" as it applies to electrical equipment? -
correct answer ✅Basic Impulse Level: the point the equipment
insulation will start to fail under surge conditions.
Briefly explain how a substation ground grid works to assure quick
operation of protective devices. -
correct answer ✅It provides a low-resistance path to earth
What is an OHGW and how does it help protect a substation from
lightening? -
correct answer ✅Over head ground wire (static wire, shield wire):
it conducts lightning strikes safely to earth and away from
substation equipment.
What is "Corona" as associated with electrical equipment? -
correct answer ✅The ionization of the air around energized high-
