🔍 Key Concepts
• Look closely at the internal blocks shown in figure B: rectifier, detector, amplifier, and the use of a current transformer (CT) feeding the relay.
• Think about which overload relay types (thermal bimetallic, thermal solder‑pot, electromagnetic, electronic) use mechanical heating elements versus electrical/electronic signal processing.
• Recall that thermal overloads are usually shown with heaters, bimetal strips, or solder pots, while electromagnetic/electronic types are often associated with CT inputs and signal conditioning blocks.
💭 Think About
• Does the diagram in figure B show any heater coils, bimetal strips, or solder pots, or does it show signal-processing blocks like filters and amplifiers?
• Which of the four answer choices would most likely need a rectifier and amplifier as part of its operation?
• If a CT is feeding the relay, is the relay probably acting on heat developed in an element, or on a processed electrical signal proportional to current?
✅ Before You Answer
• Verify whether the figure shows mechanical thermal elements (heaters, bimetal, solder) – if not, you can likely rule out the purely thermal types.
• Confirm that the presence of a CT, rectifier, detector, and amplifier indicates a design that processes an electrical signal rather than relying on direct heating.
• Before choosing, match each option with how it is typically constructed and see which one best fits a block diagram with electronic blocks instead of mechanical/thermal elements.