Question 218Electricity & Electronics - 1st Asst/Chief

70% to pass

With an AC synchronous electric propulsion motor driving a fixed-pitch propeller, whenever there is a direction reversal ordered from the bridge, there is a process of regenerative braking that is used to slow the motor down before the shaft actually reverses. Where is the energy associated with the inertia of rotation dissipated before reversal occurs?

AThe energy is dissipated at a dynamic braking resistor bank used for this purpose only.

BThe energy is dissipated at the AC synchronous electric propulsion motor itself.

CThe energy is dissipated by transferring the energy back to the electrical source.

DThe energy is dissipated at the load converter GTO controlled thyristors.

AI Explanation

The correct answer is C) The energy is dissipated by transferring the energy back to the electrical source. In an AC synchronous electric propulsion system with a fixed-pitch propeller, when a direction reversal is ordered, the motor enters a regenerative braking mode. During this process, the inertia of the rotating shaft and propeller is used to generate electricity, which is then fed back into the electrical source, rather than being dissipated as waste heat. This allows the system to slow down the motor efficiently before the shaft actually reverses direction. The other answer choices are incorrect because the energy is not dissipated at a dedicated braking resistor (A), the motor itself (B), or the load converter thyristors (D).

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