- 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 which transform alternating current (AC) electrical energy from primary to secondary side. The energy is transformed with equal frequency and approximately equal power by means of the transformer core magnetic field. Thus they provide galvanic isolation in the electrical system. The isolation transformers operate in the same way as other transformer types. But the main task is to provide the galvanic isolation in the electrical system. They can work as step-up transformer or step-down transformers but often operate with turns ratio 
. This means that the primary and secondary voltage values are equal. This is obtained with an same number of turns on the primary and secondary windings.
The isolation transformers are used in many electrical devices as computers, measurement devices or specific industry power electronic devices.
Using isolation transformers is crucial when an oscilloscope measures signals in circuits not galvanically isolated from the network, as it prevents potential short-circuits between the oscilloscope’s common point and ground. The primary role of these transformers is to enhance safety by protecting electronic components and users from electrical shocks, ensuring the primary power supply is physically separated from any secondary side connections to electronic components or grounded parts.
This means that the isolation transformer secondary side must not be grounded. It would create a physical connection between the primary and secondary transformer side. The auto transformer with common winding can not be used as isolation transformer because it has a connection between primary and secondary side. Isolation transformer provides available supplying even if the device is broken. The primary side remains under voltage which can be used to supply some alarm or warning beep circuits when the device is broken.
Isolation transformers suppress electrical noise from power supplies or electromagnetic induction, vital for sensitive devices like those in medical or measurement settings. They incorporate electrostatic shields to enhance noise suppression. Their design is critical in preventing ground loops, which are unwanted current paths that contribute to signal noise and interference.
In designing isolation transformers, it is essential to consider the capacitance values of the windings that lead to capacitive coupling. This coupling allows the AC signal to transfer from the primary to the secondary side, potentially increasing noise levels. To mitigate this, windings are typically wrapped with a grounded metal strip, forming a Faraday shield.
Isolation transformers also serve as instrument transformers for measuring high voltages, which pose risks to both operators and measurement circuits. To safely measure high voltages, step-down isolation transformers reduce these voltages to safer, manageable levels.
Application of Isolation Transformer
There is also some special application of isolating transformers, such us pulse transformers which transmit rectangular pulse signals and provide the electrical isolation. This type is suitable in some computer network designs.
