Which statement is true regarding solid state DC vs AC outputs?

Which statement is true regarding solid state DC vs AC outputs?

• A. Solid state DC outputs use transistors; AC outputs use triacs; cannot use same module for AC and DC.
• B. Solid state DC outputs use diodes; AC uses diodes too.
• C. Solid state DC outputs use CT relays.
• D. Solid state DC outputs use triacs; AC use transistors.

Answer: (A)

Solid state outputs rely on switching devices that match the type of current being controlled. For DC loads, transistors (or MOSFETs) are used because they can turn on and off cleanly with a unidirectional current. For AC loads, triacs (or SCRs) are used because they can conduct in both directions and are gated to turn on each half-cycle; they naturally reset at the zero-crossing of AC, which wouldn’t happen with DC. This is why a component designed for DC switching won’t reliably turn off a DC load if it were a triac, and why DC modules and AC modules are built with different internal devices. The statement that DC outputs use transistors and AC outputs use triacs, and that you generally can’t use the same module for both, accurately reflects how solid-state outputs are typically implemented. Other options describe devices (like diodes or CT relays) that don’t perform the switching function required for control, making them incorrect.

Solid state outputs rely on switching devices that match the type of current being controlled. For DC loads, transistors (or MOSFETs) are used because they can turn on and off cleanly with a unidirectional current. For AC loads, triacs (or SCRs) are used because they can conduct in both directions and are gated to turn on each half-cycle; they naturally reset at the zero-crossing of AC, which wouldn’t happen with DC. This is why a component designed for DC switching won’t reliably turn off a DC load if it were a triac, and why DC modules and AC modules are built with different internal devices. The statement that DC outputs use transistors and AC outputs use triacs, and that you generally can’t use the same module for both, accurately reflects how solid-state outputs are typically implemented. Other options describe devices (like diodes or CT relays) that don’t perform the switching function required for control, making them incorrect.