Question 62 QMED02 - Electrician-Refrigerating Engineer

The Correct Answer is D **Explanation for Option D (hand-cranked generator):** The component labeled "B" in electrical schematics, particularly within older or specialized military/communications contexts (like those often featuring illustrations designated by numbers such as EL-0093), often represents a power source that can be operated manually. The symbol for a **hand-cranked generator** (sometimes denoted as G-HND or similar) typically consists of a circle (representing the generator or dynamo) with an arrow or a zig-zag line exiting one side, visually suggesting the mechanical input mechanism (the crank handle). This component is used to generate the necessary AC or DC voltage to power field equipment, such as radio transmitters/receivers, when grid power or batteries are unavailable. **Explanation of Incorrect Options:** **A) selsyn motor:** A selsyn (or synchro) motor is used for remote position sensing or data transmission (e.g., transmitting the angular position of a compass to a remote indicator). Its schematic symbol generally represents a three-phase motor or transformer configuration, which looks significantly different from the basic generator symbol with a manual crank indication. **B) bridge rectifier:** A bridge rectifier is a circuit component (usually four diodes arranged in a specific configuration) used to convert AC voltage into pulsating DC voltage. Its symbol is typically drawn as a diamond shape containing diodes, or simply represented by the standard rectifier symbol, not the rotating machine symbol associated with a generator. **C) shielded lamp:** A shielded lamp (or pilot lamp/indicator light) is typically symbolized by a circle containing a cross (X) or filament representation, sometimes enclosed in a dashed line to indicate shielding. It is an output device (a load) and does not represent a power generation source like a hand-cranked generator.