In solid state DC output modules, when does the circuit close?

In solid state DC output modules, when does the circuit close?

• A. When a transistor conducts (on).
• B. When a diode is reverse-biased.
• C. When a transformer energizes.
• D. When a switch is opened.

Answer: (A)

Solid state DC output modules close the circuit when the switching device conducts. The load is connected to the supply only when the transistor (the switching element) is turned on and provides a low-resistance path. When the transistor is off, the path is open and current cannot flow. In DC output stages, this on-state is what completes the circuit. The other scenarios—a diode that is reverse-biased blocking current, a transformer energizing, or a switch being opened—do not create the conduction path needed to close the circuit.

Solid state DC output modules close the circuit when the switching device conducts. The load is connected to the supply only when the transistor (the switching element) is turned on and provides a low-resistance path. When the transistor is off, the path is open and current cannot flow. In DC output stages, this on-state is what completes the circuit. The other scenarios—a diode that is reverse-biased blocking current, a transformer energizing, or a switch being opened—do not create the conduction path needed to close the circuit.