A power supply unit (PSU), commonly known as a power supply, is an electronic component that converts electricity from the main power grid into a voltage and current suitable for powering electronic components in electrical devices. It serves as a critical electrical or mechanical adaptation element that provides power to various electronic systems.
What is a Power Supply?
A power supply converts mains voltage to another voltage (either direct or alternating). Lower voltages are more appropriate for electronic and electrical equipment found in homes. While different technologies exist, they all operate on the same fundamental principle: adjusting the device's voltage to be as stable as possible, accommodating the power requirements of the appliance despite variations in the electrical network.
Types of Power Supplies
Power Supply for Electrical Panels (Voltage Transformer)
A very low voltage power supply is essential for many domestic appliances and circuits with voltages not exceeding 50V. An integrated power supply is highly recommended for devices connected to electrical panels, offering a clean, seamless installation. Manufacturers typically provide transformers for various applications such as doorbells, intercoms, and communication boxes.
Filtered Rectified Power Supply
This is the oldest technology, also known as a linear power supply. Such a power supply unit contains a transformer that reduces the 220V, 50 Hz alternating current to a lower voltage of around ten volts while maintaining the 50 Hz frequency.
A 'rectifier' stage then transforms the alternating voltage (which oscillates between positive and negative) into a consistently positive voltage. This voltage is subsequently smoothed to ensure it remains above a specific threshold.
Switching Power Supply
A highly successful power supply type that first emerged in the 1970s, switching power supplies are efficient, compact, and cost-effective. Their efficiency ranges from 75% to 95%.
The operating principle is relatively simple: mains voltage is transformed into a high direct current of approximately 300V. A transistor then "chops" this voltage by opening and closing several thousand times per second. This pulse train is subsequently converted back to direct current. The capacitor's conducting duration allows for output voltage level adjustment, which is electronically regulated to maintain maximum stability.
Caution is advised, as switching power supplies tend to generate electromagnetic interference on electrical networks that can disrupt other devices. To mitigate this, it is recommended to choose high-end power supplies with effective filters. This protects both your devices from network disturbances and the network from disturbances created by the chopping process.
Laboratory Power Supply
Laboratory power supplies are used to power experimental electronic circuits and conduct tests across various intensity and voltage ranges. They typically offer one or more outputs where voltage can be adjusted from 0V to several dozen volts. Additionally, the maximum intensity can be regulated.
A significant advantage of laboratory power supplies is built-in protection against short circuits, minimizing the risk of damage during circuit assembly.
Mechanical Power Supplies
These enable mechanical adaptation between circuit breakers and other electrical components.
