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Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
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The energy of traveling wave is
Absorbed by surge arrester
Reflected by surge arrester
Diverted by surge arrester
Partly absorbed and partly diverted by surge arrester
Partly absorbed and partly diverted by surge arrester
A surge arrester acts as a non-linear protective device that limits overvoltages on power equipment. It operates by providing a low-impedance path to ground during a surge, effectively diverting the bulk of the transient energy while absorbing a portion of the surge due to its internal resistance and non-linear characteristics.
A surge arrester acts as a non-linear protective device that limits overvoltages on power equipment. It operates by providing a low-impedance path to ground during a surge, effectively diverting the bulk of the transient energy while absorbing a portion of the surge due to its internal resistance and non-linear characteristics.
VclampтАЛ=IsurgeтАЛтЛЕRnonlinearтАЛ тАФ represents the voltage clamping effect where resistance drops as surge current increases
EabsorbedтАЛ=тИлV(t)тЛЕI(t)dt тАФ represents the energy dissipated as thermal heat within the arrester blocks
When an incoming traveling wave hits a surge arrester, the device transitions from a high-impedance state (insulating) to a low-impedance state (conducting) as the voltage exceeds the sparkover or threshold level. This bifurcation of the wave energy occurs because the arrester's non-linear resistive element (usually Metal Oxide Varistor/MOV) dissipates energy as heat while simultaneously shunting the excess current to the ground, thus maintaining the voltage at a safe clamp level.
Surge arresters use non-linear materials like Silicon Carbide (SiC) or Zinc Oxide (ZnO).
The primary goal is to limit the transient overvoltage to a level below the Basic Insulation Level (BIL) of protected equipment.
The arrester must handle the surge energy without physical damage (thermal runaway).
Excellent non-linear V-I characteristics
Fast response time to lightning and switching surges
Subject to thermal degradation over time
High leakage current can occur if the MOV disc is damaged
Transformer substations
High-voltage transmission line terminal protection
Modern surge arresters are primarily Gapless Metal Oxide Surge Arresters (MOSA).
Option B (Reflected) is incorrect because the arrester's purpose is to prevent excessive reflection by absorbing and diverting energy, whereas pure reflection usually happens at open-circuit or high-impedance ends.
D is correct тАФ The surge arrester provides a parallel path to ground for the surge current (diversion) while the internal material properties convert part of the electromagnetic energy into heat (absorption).
Always remember that in power systems, ideal protection equipment manages to both dissipate energy as heat and provide a low-impedance path to earth, rather than just forcing the energy to travel back up the line.