Introduction to Lightning or Surge Arrester | Video #2

Summary

Surge arresters, or lightning arresters, are crucial devices that protect power systems from overvoltage caused by lightning strikes or switching operations. While they are commonly associated with lightning protection, they also limit overvoltage due to switching surges. These arresters safeguard critical equipment such as transformers, transmission lines, and generators. Surge arresters are typically installed at key points like incoming feeders, transformer terminals, and capacitor banks. Metal-oxide surge arresters, particularly Zinc Oxide (ZnO), have been the standard since the late 1980s. Non-gapped and externally-gapped line arresters are used for transmission lines. Surge arresters play a vital role in maintaining the safety and stability of power systems.

Takeaways

• 😀 Surge arresters protect power systems from overvoltage caused by lightning strokes or switching operations.
• 😀 Surge arresters help prevent damage to power systems by limiting overvoltages.
• 😀 The purpose of surge arresters is often misunderstood as only protecting from lightning strikes, but they also protect against switching surges.
• 😀 Surge arresters are essential in protecting critical equipment in substations, such as transformers.
• 😀 Surge arresters are used to protect transmission lines as well as other equipment like capacitor banks and generators.
• 😀 Surge arresters are typically connected phase-to-ground, first in the incoming feeder of the substation.
• 😀 In a substation, the first device connected is typically the lightning arrester.
• 😀 Modern surge arresters for substations use metal-oxide (MO) technology, especially Zinc Oxide (ZnO), and have been used since the late 1980s.
• 😀 Non-gapped line arresters (NGLA) and externally-gapped line arresters (EGLA) are commonly used for transmission lines.
• 😀 An interview question that may come up is 'Which device is connected first in a substation?' The answer is the lightning arrester.

Q & A

What are the main causes of overvoltage in a power system?

Overvoltage in a power system can be caused by lightning strokes or switching operations.

What is the purpose of a surge arrester or lightning arrester?

The purpose of a surge arrester or lightning arrester is to limit overvoltage that may occur due to lightning strokes or switching surges.

Do surge arresters only protect against lightning-induced overvoltage?

No, surge arresters protect against both lightning-induced and switching-induced overvoltages.

Which equipment in a substation is typically protected by a surge arrester?

Surge arresters protect important substation equipment such as transformers, transmission lines, capacitor banks, and generators.

Where is a surge arrester connected in a substation?

A surge arrester is connected phase to ground at the incoming feeder as the first apparatus, and also at the terminals of equipment like transformers, capacitor banks, and generators.

Which device is connected first in a substation?

The lightning arrester is the first device connected in a substation.

What type of surge arresters are commonly used in substations?

Metal-oxide (MO) surge arresters, particularly Zinc Oxide (ZnO) types without gaps, have been the standard for substation applications since the late 1980s.

What types of surge arresters are used for transmission lines?

For transmission lines, non-gapped line arresters (NGLA) and externally-gapped line arresters (EGLA) are used.

Why is it important to limit overvoltage in a power system?

If overvoltage is not minimized, it can cause severe damage to electrical equipment and compromise the stability of the entire power system.

What are switching surges, and why should they be controlled?

Switching surges are transient overvoltages caused by switching operations such as circuit breaker actions or load changes. They should be controlled to prevent insulation failure and equipment damage.

What makes metal-oxide surge arresters more effective than older types?

Metal-oxide surge arresters, especially those using zinc oxide, offer superior energy absorption, faster response time, and better protection without the need for gaps.

How does a surge arrester function during normal and overvoltage conditions?

During normal voltage conditions, the surge arrester offers high resistance and remains inactive. When overvoltage occurs, its resistance drops sharply, diverting excess current safely to the ground.