A ___ changes primary voltage to lower voltage.

A ___ changes primary voltage to lower voltage.

• A. Gateway
• B. Control transformer
• C. PLC
• D. Universal input

Answer: (B)

Transformers change voltage levels by using two windings on a shared magnetic core. The primary winding connects to the higher voltage, and the secondary provides a lower voltage according to the turns ratio. This is exactly what a control transformer does in electrical panels: it steps down line voltage to a safe, usable level for control circuits—such as relays, contactors, and PLC input modules—while providing galvanic isolation between the two sides. The lower voltage on the secondary keeps the control circuitry safe and reliable. A gateway translates data between networks and doesn’t alter voltage. A PLC is a controller, not a device designed to step down voltage (though it may operate on low-voltage power). A universal input is an input channel type, not a device that changes voltage.

Transformers change voltage levels by using two windings on a shared magnetic core. The primary winding connects to the higher voltage, and the secondary provides a lower voltage according to the turns ratio. This is exactly what a control transformer does in electrical panels: it steps down line voltage to a safe, usable level for control circuits—such as relays, contactors, and PLC input modules—while providing galvanic isolation between the two sides. The lower voltage on the secondary keeps the control circuitry safe and reliable. A gateway translates data between networks and doesn’t alter voltage. A PLC is a controller, not a device designed to step down voltage (though it may operate on low-voltage power). A universal input is an input channel type, not a device that changes voltage.