Delving into Isolation Transformers: Principles and Functions Explained

Isolation transformers, also known as safety transformers, are transformers designed to electrically isolate the input winding from the output winding. They are used to isolate two or more coupled circuits electrically. The primary function of isolation transformers includes facilitating safe operations during machine maintenance and upkeep, providing protection against lightning and filtering functions. Their design prevents accidental contact with live components, thereby ensuring a safer working environment.

Isolation transformers serve as essential safety power devices, commonly used in machine maintenance and protective applications. They are characterized by electrical isolation between the input and output windings. Typically, isolation transformers are 1:1 transformers, meaning the voltage ratio between the input and output sides is the same. For instance, in a single-phase isolation transformer, the primary and secondary voltages could both be 220V, ensuring safe electrical isolation for machine maintenance and other applications requiring electrical isolation.

Moreover, in three-phase isolation transformers, both the primary and secondary voltages could be 380V, suitable for electrical protection and isolation applications within three-phase power systems.

Principles of Isolation Transformers:

The principle of isolation transformers involves utilizing the basic principle of electromagnetic induction to electrically isolate the input winding (primary winding) from the output winding (secondary winding). The main purpose is to prevent dangers arising from accidental contact with live components or potentially energized metal parts due to insulation damage.

Isolation transformers operate similarly to conventional dry-type transformers based on electromagnetic induction. They consist of a primary iron core surrounded by one or more windings. When the primary winding is energized, a magnetic field is induced through the iron core to the secondary winding, thereby inducing a corresponding voltage in the secondary winding. However, unlike conventional transformers, the windings of isolation transformers are not directly electrically connected; they transfer energy through magnetic induction.

Key Functions of Isolation Transformer Principles:

• Electrical Isolation: Isolation transformers electrically isolate the input and output windings, effectively preventing direct electrical connections between them. This isolation helps in blocking electrical interference and noise propagation between circuits, enhancing system stability and safety. Especially in environments with high voltages or dangerous electrical potentials, isolation transformers prevent accidental electrical shocks.
• Suppression of High-Frequency Noise: Isolation transformers feature iron core materials with high-frequency loss characteristics, effectively absorbing and suppressing high-frequency signals and noise. This prevents interference signals from entering control circuits or other sensitive circuits, improving system resistance to interference and stability.
• Protection of Personal Safety: In electrical systems, especially low-voltage power supply systems, neutral lines (zero lines) are typically connected to ground potential. This poses a risk of electrical shock when exposed to live components. Isolation transformers, by floating the secondary side (output side) relative to ground potential, prevent the formation of a complete circuit even when a person contacts live components, reducing the risk of electrical shock and ensuring personal safety.

Typical Applications of Isolation Transformers:

• Isolation of Equipment from AC Power Lines: The most common application of isolation transformers is to electrically isolate equipment from AC power lines. For example, in switch-mode power supplies (SMPS), isolation transformers separate the primary circuit from the secondary circuit, preventing circuit interference and accidental electrical shock.
• Safe Fault Diagnosis: During circuit troubleshooting, isolation transformers provide a safe grounding point, preventing short circuits between oscilloscope probes and the main circuit, thus safeguarding essential components and testing equipment.
• Elimination of Grounding Issues: Isolation transformers eliminate safety hazards caused by ground potential differences. By isolating the ground reference point to a safe location, they prevent circuit short-circuiting and damage caused by ground issues.
• Diagnosis and Correction of Grounding Circuits: In situations where multiple devices with individual grounding return paths are interconnected, isolation transformers are used to diagnose and correct grounding circuit issues, identifying the sources of ground leakage currents.
• High-Frequency Noise Suppression: Isolation transformers reduce the transmission of high-frequency noise and interference between circuits. Their series inductance and Faraday shielding effectively suppress capacitive coupling between the two ends of the transformer.

In conclusion, isolation transformers play a critical role in electrical systems by providing electrical isolation, safety protection, and interference suppression. They are essential components in circuit design and maintenance, ensuring system reliability and safety.

Tags：ITEU-SP4K