Which electrical component is used to decrease primary voltage to a lower voltage for control circuits?

Which electrical component is used to decrease primary voltage to a lower voltage for control circuits?

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

Answer: (D)

To power control circuits safely, you need a device that lowers the main supply voltage while keeping the control and power circuits electrically separate. A control transformer does exactly this: it uses a primary winding connected to the higher voltage and a secondary winding that delivers a lower, suitable voltage for relays, contactors, timers, and sensing circuits. It also provides galvanic isolation between the control and power sides, which protects equipment and operators. The other options don’t perform this voltage-reduction function: universal input refers to power supplies that accept a wide range of input voltages but don’t step voltage down for control circuits; a PLC is a programmable controller that may require a lower voltage supply but isn’t a device that reduces voltage itself; a gateway is a network device for data communication, not for changing voltage.

To power control circuits safely, you need a device that lowers the main supply voltage while keeping the control and power circuits electrically separate. A control transformer does exactly this: it uses a primary winding connected to the higher voltage and a secondary winding that delivers a lower, suitable voltage for relays, contactors, timers, and sensing circuits. It also provides galvanic isolation between the control and power sides, which protects equipment and operators.

The other options don’t perform this voltage-reduction function: universal input refers to power supplies that accept a wide range of input voltages but don’t step voltage down for control circuits; a PLC is a programmable controller that may require a lower voltage supply but isn’t a device that reduces voltage itself; a gateway is a network device for data communication, not for changing voltage.