Coal India Interview Questions and Answers

The resistance value of tripping & closing coil of VCB varies depending on the manufacturer and model.

• The resistance value can be found in the manufacturer's manual or datasheet.

• It is important to use the correct resistance value to ensure proper functioning of the VCB.

• The resistance value may also vary depending on the voltage rating of the VCB.

• For example, the ABB VD4 VCB has a tripping coil resistance of 50-60 ohms and a closing coil resistance of 20-30 ohms.

The contact resistance of VCB is typically very low.

• VCB stands for Vacuum Circuit Breaker.

• The contact resistance is the resistance between the contacts of the breaker when it is closed.

• The contact resistance of VCB is typically in the range of micro-ohms.

• Low contact resistance is important for efficient operation of the breaker.

• High contact resistance can cause overheating and damage to the breaker.

• The contact resistance can be affected by factors such as the material of the ...read more

The minimum height at which the safety belt should be used is determined by the height of the individual and the specific safety regulations in place.

• The minimum height requirement for safety belt usage varies depending on the country and jurisdiction.

• In the United States, for example, the minimum height for safety belt usage is typically around 4 feet 9 inches (145 cm).

• Other factors such as age, weight, and type of vehicle may also influence the minimum height requirement.

• It...read more

Outages for line/switchyard are managed by the load dispatch centre through coordination and communication.

• Outages are scheduled in advance to minimize impact on the grid and consumers.

• Load dispatch centre coordinates with the concerned authorities to plan and execute the outage.

• Alternative arrangements are made to ensure continuity of power supply during the outage.

• Regular updates are provided to stakeholders regarding the status of the outage and expected restoration time.

Double bus system is important for ensuring redundancy and reliability in power distribution.

• Enhances reliability by providing backup in case of failure in one bus

• Allows for maintenance work to be carried out on one bus while the other remains operational

• Reduces the risk of power outages and downtime

• Commonly used in critical infrastructure such as hospitals, data centers, and industrial facilities

Smart metering enhances energy management, while O&M of substations ensures reliability and efficiency in power distribution.

• Smart metering allows real-time monitoring of energy consumption, enabling better demand management.

• Advanced metering infrastructure (AMI) can facilitate remote readings and reduce operational costs.

• O&M of substations involves regular inspections, maintenance schedules, and upgrades to ensure equipment reliability.

• For example, predictive maintenance usi...read more