Question 266Electricity & Electronics - QMED

The correct answer is C) Frequency meter, power factor or reactive power meters, and synchronizing lamps or synchroscope. In an AC electrical distribution system, the main switchboard requires additional devices that are not necessary for a DC system. This is because AC systems need to maintain a constant frequency and proper synchronization between the generators and the loads, which is not a concern for DC systems. The frequency meter, power factor/reactive power meters, and synchronizing lamps/synchroscope are used to monitor and control the AC system's frequency and ensure proper synchronization, which is crucial for the safe and efficient operation of the electrical distribution system. The other options, while important for electrical systems, are not specific requirements for an AC main switchboard compared to a DC main switchboard.