Question 27 MODE01 - Chief MODU Engineer

The Correct Answer is C ### Why Option C is Correct: Auxiliary diesel engines (used typically for power generation, propulsion, or emergency backup on ships, large industrial sites, or vehicles) require powerful, reliable starting systems. The most common and robust method for starting these engines is through high-torque electric starting motors powered by dedicated battery banks. These batteries (usually 12V or 24V systems, often banks of heavy-duty lead-acid or lithium-ion batteries) provide **direct current (DC)** at very high amperage (hundreds or even thousands of amps momentarily) to drive the starter motor. This system is chosen because battery power (DC) is immediately available, provides the necessary high current burst needed to overcome the engine's compression resistance, and is independent of the main electrical grid, making it ideal for starting operations. ### Why Other Options Are Incorrect: **A) alternating current transformers:** Transformers only work with AC power and change voltage/current levels. While AC power is used extensively elsewhere, the actual starting motors on these engines rely on DC power from batteries for high-current, low-voltage starting capability. **B) 400 cycle per second motor-generator power:** 400 Hz power is standard in aviation and specialized military applications due to weight savings, but it is highly unusual and inefficiently complex for the standard starting procedure of a typical ship or industrial auxiliary diesel engine. Standard industrial and marine power is usually 50 or 60 Hz, and starting is done via DC batteries, not a specialized high-frequency AC system. **D) low amperage, high voltage AC power:** Electric starting motors require extremely **high amperage** (current) at **low voltage** (typically 12V or 24V) to generate the necessary torque. Low amperage, high voltage AC power is fundamentally unsuited for this high-torque application and would present significant safety and insulation challenges in a mobile or industrial environment.