If a transformer is connected to a DC supply, it will not operate as intended. Transformers are designed to work with alternating current (AC) because they rely on the alternating magnetic fields induced by AC to transfer energy between the primary and secondary windings. When DC voltage is applied to the transformer, it generates a steady magnetic field in the core without the alternating nature required for induction. As a result, there is no fluctuating magnetic field to induce voltage in the secondary winding, causing the transformer to essentially act as an inductor. This means no voltage is induced in the secondary winding, and therefore, the transformer cannot step up or step down the voltage as it does with AC.
Connecting the primary of a transformer directly to a DC source results in a significant issue known as DC magnetization. DC magnetization causes the transformer core to become magnetically saturated in one direction, leading to high core losses, excessive heating, and potential damage to the transformer windings and insulation. The primary winding draws excessive current, which can exceed the rated current capacity of the winding and may result in overheating or even failure of the transformer.
In general, transformers are not designed to be connected directly to DC voltage sources. The design and operation of transformers rely on the alternating magnetic fields induced by AC voltage to transfer energy efficiently between windings. Attempting to connect DC to a transformer can lead to malfunction, overheating, and potentially irreversible damage to the transformer due to DC magnetization effects and excessive current draw.
Transformers cannot work with DC supply because they rely on the principles of electromagnetic induction, which require a changing magnetic flux. In AC operation, the alternating current in the primary winding creates a fluctuating magnetic field in the transformer core. This changing magnetic flux induces a voltage in the secondary winding through mutual induction. However, with a DC supply, there is no alternating current to create a changing magnetic flux. As a result, there is no voltage induced in the secondary winding, and the transformer cannot perform its intended function of stepping up or stepping down voltage.
In a DC power supply, transformers are typically used in conjunction with other components such as rectifiers and capacitors in a circuit known as a switching power supply or a DC-DC converter. In these applications, transformers are used to isolate or step up/down voltage levels after converting AC to DC through rectification. The transformer’s primary role in a DC power supply is usually to provide isolation, voltage transformation, or impedance matching depending on the specific requirements of the power supply design.