- Isolation Transformer Definition: An isolation transformer is defined as an electromagnetic device that transfers AC electrical energy between two circuits while maintaining the same frequency and providing galvanic isolation.
- Safety and Protection: Essential for protecting both electronic components and operators from electrical shocks, particularly in environments where equipment is not galvanically isolated.
- Noise and Interference Control: Isolation transformers help suppress electrical noise and prevent ground loops, crucial for maintaining signal integrity in sensitive devices.
- Design Features: These transformers may include electrostatic shields and are designed to avoid any grounding on the secondary side to enhance safety and functionality.
- Broad Applications: Besides general electrical safety, isolation transformers are integral in medical, measurement, and computer networking applications, facilitating safe and accurate operations.
Transformers are electromagnetic devices that transfer alternating current (AC) electrical energy from the primary to the secondary side at equal frequency and approximately equal power, through the transformer core magnetic field. That magnetic link gives the electrical system galvanic isolation. Isolation transformers work like other transformer types, but their main task is precisely that isolation. They can act as a step-up transformer or step-down transformers, yet they often run at a turns ratio of 
, so the primary and secondary voltages are equal, obtained with the same number of turns on both windings.
Isolation transformers serve in many electrical devices, such as computers, measurement devices and industrial power electronic equipment.
An isolation transformer matters when an oscilloscope measures signals in circuits that are not galvanically isolated from the network: it prevents short-circuits between the oscilloscope’s common point and ground. The primary role of these transformers is safety, protecting electronic components and users from electric shock by physically separating the primary power supply from any secondary-side connections to electronic components or grounded parts.
The secondary side of an isolation transformer must not be grounded: grounding would create a physical connection between the primary and secondary sides. An autotransformer with a common winding cannot serve as an isolation transformer because its primary and secondary sides share a connection. Even if the supplied device fails, the primary side stays energised, and that voltage can supply alarm or warning-beep circuits.
Isolation transformers suppress electrical noise from power supplies or electromagnetic induction, which matters for sensitive medical and measurement devices. Electrostatic shields add further noise suppression. Their design also prevents ground loops, unwanted current paths that create signal noise and interference.
Designers of isolation transformers must consider the capacitance between the windings, because that capacitive coupling can carry the AC signal from the primary to the secondary side and raise noise levels. To mitigate it, the windings are wrapped with a grounded metal strip that forms a Faraday shield.
Isolation transformers also serve as instrument transformers for measuring high voltages, which endanger both operators and measurement circuits. Step-down isolation transformers reduce those voltages to safer, manageable levels.
Application of Isolation Transformer
One special application of isolating transformers is the pulse transformer, which transmits rectangular pulse signals while providing electrical isolation. This type suits some computer network designs.
