Which type of arrester has the following assemblies?

a. Series spark gaps

b. Non-linear resistor discs in series 

The correct answer is option 4.

Lightning arrester

A Lightning Arrester is a protective device that protects electrical equipment from high voltage surges caused by lightning strikes.

They are usually installed at the top of transmission poles and buildings and provide an easy path for the surge voltage from lightning to flow to the ground.

Types of lightning arrester

Valve-type lightning arrester

A Valve Type Arrester consists of the following main components:

• Series Spark Gaps: These are used to block normal system voltage and operate only when there is an overvoltage.
• Non-linear Resistor Discs: These resistors limit the surge current by reducing their resistance when a high voltage surge appears.

Rod gap lightning arrester

• It is one of the simplest types of Lightning Arresters.
• There is a gap between the end of the two rods. These two rods get connected to the earth and the line directly. The gap gets filled with air.
• When there is a higher voltage on the line, the air ionizes, producing a spark. In this way, the fault current passes to the earth.

Expulsion-type lightning arrester

• The expulsion type arrester is an improvement over the rod gap arrester.
• This type of arrester is also known as a protector tube or expulsion gap and it is commonly limited to systems operating at voltages up to 33kV.
• This arrester consists of a tube made up of very effective fiber, isolating the spark gap and an interrupting spark gap inside the fiber tube.

Multi-gap arrester

• A multigap arrester has multiple air gaps with the help of several cylinders, which are made up of Zinc alloy.
• The top cylinder is connected to the line while the bottom cylinder is connected to the ground with a series resistor.
• In the event of a surge, the air insulation will break down, and the surge will pass through the cylinders and the air gaps to the ground rather than through the shunt resistor.