DECTAR MOBILE APP Interview Questions and Answers

Earthing is crucial for safety in substations and tunnels. Materials used include copper, steel, and galvanized iron.

• Earthing ensures that any electrical faults are safely discharged to the ground.

• In substations, earthing is necessary to protect equipment and personnel from electrical hazards.

• In tunnels, earthing is important to prevent the buildup of static electricity and to protect against lightning strikes.

• Materials used for earthing include copper, steel, and galvanized ...read more

Three phase voltage is not simply the sum of single phase voltages due to different configurations and power distribution requirements.

• Three phase power systems are designed to be more efficient and balanced compared to single phase systems.

• In a three phase system, the voltage between any two phases is 440V, not the sum of single phase voltages (220V).

• The total power in a three phase system is proportional to the square root of 3, hence the voltage is not simply tripled.

• Highe...read more

GIS substations use gas-insulated switchgear while AIS substations use air-insulated switchgear.

• GIS substations are more compact and require less space than AIS substations.

• GIS substations are more expensive to install and maintain than AIS substations.

• GIS substations are more reliable and have lower maintenance costs than AIS substations.

• AIS substations are more commonly used for lower voltage applications while GIS substations are used for higher voltage applications.

• Exampl...read more

Isolator is a switch that isolates a circuit from power source while insulator is a material that does not conduct electricity.

• Isolator is used to disconnect a circuit from power source for maintenance or safety purposes.

• Insulator is used to prevent the flow of electricity through a material.

• Isolator is a mechanical device while insulator is a material property.

• Examples of isolators include circuit breakers, disconnect switches, and fuses.

• Examples of insulators include rubber...read more

Circuit breakers used in GIS are designed to interrupt the flow of electrical current in case of a fault.

• GIS stands for Gas Insulated Switchgear

• Circuit breakers used in GIS are typically SF6 circuit breakers

• SF6 circuit breakers use sulfur hexafluoride gas to extinguish the arc

• GIS circuit breakers are compact and require less maintenance compared to traditional air-insulated switchgear