A power supply converts AC (Alternating Current) from the mains into DC (Direct Current) that electronic circuits and industrial devices can use. Most electronic components — like sensors, controllers, and PLCs — require a steady DC voltage, typically 24V DC, while the power source from the wall is 230V AC. The conversion from AC to DC happens through several stages inside the power supply: rectification, filtering, and voltage regulation.
1. Rectification:
The first step uses diodes arranged in a bridge rectifier circuit to convert the alternating current into a pulsating DC. In AC, the voltage constantly changes direction, but diodes allow current to flow only in one direction, effectively removing the negative half of the waveform and creating a unidirectional output.
2. Filtering:
After rectification, the DC voltage still contains ripples or fluctuations. To smooth this out, the power supply uses capacitors (and sometimes inductors) as filters. These components store and release electrical energy, filling in the gaps in the waveform and providing a more stable DC output.
3. Regulation:
Finally, the voltage passes through a voltage regulator — either linear or switching — which ensures the output remains constant even if the input voltage or load changes. In modern systems, this is done by an SMPS (Switched-Mode Power Supply) circuit, which is compact, efficient, and reliable for industrial use.
In simple terms, a power supply converts AC to DC by first turning AC into pulsating DC (rectification), then smoothing it (filtering), and finally stabilizing it (regulation). This ensures a clean and reliable DC voltage output that powers controllers, PLCs, and sensors in automation systems safely and efficiently.
A power supply converts AC to DC by changing the alternating current from the mains into a stable direct current that electronic equipment can safely use. Most industrial and electronic devices need DC power because it provides consistent voltage and prevents fluctuations that can damage sensitive components.
The conversion process begins with a transformer. Its job is to step down or step up the incoming AC voltage to the required level. For example, if a device needs 24V DC, the transformer reduces 230V AC to a suitable lower AC voltage before it moves to the next stage.
Next comes the rectifier circuit, usually made up of diodes. The rectifier allows current to flow in only one direction, converting the alternating current into pulsating DC. Although this DC has ripples, it now flows in a single direction instead of alternating.
To make the DC smooth and steady, the filter circuit uses capacitors or inductors to remove the ripples and store energy for stable output. After filtering, the DC becomes cleaner and more suitable for sensitive electronic circuits.
Finally, a voltage regulator maintains a constant DC output even if the input voltage or connected load varies. This ensures reliable power delivery to equipment like PLCs, control panels, and automation systems. That’s how a power supply converts AC to DC — step by step, from transformation to regulation.