This type of solid-state relay uses a magnetic field to isolate the control circuit from the load?

This type of solid-state relay uses a magnetic field to isolate the control circuit from the load?

• A. Opto-isolated relays
• B. Reed-controlled AC relays
• C. Triac-based AC relays
• D. Power transistors for DC loads

Answer: (B)

The idea being tested is electrical isolation between the control side and the load side achieved through magnetic actuation. A reed-controlled relay accomplishes this by using a coil on the control side to create a magnetic field. That field moves a pair of ferromagnetic reeds to open or close the load-side contacts. Because the coil and the contact circuit are physically separate with no direct electrical connection, there’s galvanic isolation between the control and load circuits. The actuation is magnetic, not electrical, which is why this type is the one that fits the description. Opto-isolated relays isolate via light through a photodetector, not a magnetic field. Triac-based AC relays are solid-state switches and don’t rely on magnetic coupling for isolation. Power transistors used for DC loads are simply electronic switches without inherent isolation between control and load.

The idea being tested is electrical isolation between the control side and the load side achieved through magnetic actuation. A reed-controlled relay accomplishes this by using a coil on the control side to create a magnetic field. That field moves a pair of ferromagnetic reeds to open or close the load-side contacts. Because the coil and the contact circuit are physically separate with no direct electrical connection, there’s galvanic isolation between the control and load circuits. The actuation is magnetic, not electrical, which is why this type is the one that fits the description.

Opto-isolated relays isolate via light through a photodetector, not a magnetic field. Triac-based AC relays are solid-state switches and don’t rely on magnetic coupling for isolation. Power transistors used for DC loads are simply electronic switches without inherent isolation between control and load.