MCQ Subject: Electrical Machines & Transformers

What is the primary purpose of a tap changer in a transformer?

In a synchronous motor, which of the following operating conditions corresponds to the motor behaving as an inductive load?

In a transformer, which method involves changing the number of turns in the primary winding to regulate voltage?

Under no-load conditions, a transformer’s power factor is primarily determined by which of the following?

What is the primary distinction in rotor operation between synchronous motors and asynchronous (induction) motors in electrical machines?

In a three-phase transformer, which of the following correctly describes the line voltage (V_L) to phase voltage (V_ph) relationship in star and delta connections?

A transformer experiences dangerously high current when its secondary is connected in a specific manner without any load. Which connection type leads to this condition?

In transformers, why is the efficiency at no-load typically the lowest?

Which cooling method is typically used in oil-cooled transformers with enhanced heat dissipation through external airflow mechanisms?

Which of the following best explains why double-winding transformers are generally more efficient than autotransformers for high voltage applications?