What Makes a Power Supply Isolated - Another Teaching Moment | DigiKey

An isolated power supply prevents the direct conduction of voltage or noise between its input and output by using a transformer or similar isolation method. This separation introduces protective resistive and dielectric barriers that help block excessive voltage or electrical "feedback," which could otherwise damage equipment or endanger users. Isolated systems utilize different reference points: the Primary Reference (input side), the Secondary Reference (output side, often floating or grounded separately), or the Chassis/Earth Ground (which provides a physical safety connection). The level of protection is indicated by the isolation voltage, which reflects how much voltage the isolation barrier can withstand without allowing conduction. Benefits of isolated supplies include added safety for users, reduced risk of equipment damage, and noise reduction by preventing interference from traveling through shared grounds