What Are the Different Functions of Isolation Transformers and Surge Protective Devices

Isolation transformers and Surge Protective Devices (SPDs), among other components of electrical systems, have individual purposes of their own. Isolation transformers offer a shield of impregnability; SPDs, on the other hand, are always ready to catch and neutralise transient voltage spikes. Understanding these devices' respective functions is critical as they are necessary for optimum performance in various electrical applications.

What are Isolation Transformers?

Isolation transformers are essential elements in electrical systems that physically and electrically separate primary and secondary circuits. These devices use magnetic induction to transmit electrical energy between circuits without altering frequency. Isolation transformers are commonly utilised in transmission and distribution networks to regulate voltage levels. Installing an isolation transformer between power supply lines reduces voltage spikes, protecting loads from potential damage. These transformers reduce ground loop interference and noise effects, which improves the system's overall efficiency and dependability.

How an Isolation Transformer Works?

An isolation transformer is the key component of electrical systems since it ensures physical and electric separation between two circuits. It uses magnetic coupling technology to transfer electrical energy securely from the primary to the secondary circuit.

Different functions of isolation transformers are mentioned below: 

Voltage Spike Reduction

The crucial role of an isolation transformer is to reduce the unstable electric surges in supply lines. These transients often occur due to lightning, static electricity, or fast voltage changes. It can be a potential problem as it can cause interruption or damage to service and equipment if the output is large enough.

Voltage Spike Handling Mechanism

When a voltage spike occurs on the primary side, the isolation transformer inductive primary winding reacts. This inductive characteristic contributes to an exponential increase in current, so it cannot generate instantaneous spikes. As the current goes up, it also raises the flux, resulting in a surge in the secondary voltage. However, both primary and secondary windings' inductive properties will cease the spike in the secondary circuit.

Ground Loop Interference Elimination

The transformers are tested on two essential features: preventing ground loop interference and noise effects. These transformers isolate load equipment or the secondary side from the grounding, which leads to a cleaner and more stable power supply. However, it is particularly important for devices that cannot tolerate power supply distortion, such as measurements, laboratories, and medical equipment.

Purpose and Construction

Isolation transformers are built in the same fashion as standard core-type or power transformers but also have electrostatic shields to ensure complete isolations of the primary and secondary windings. Uniquely, the autotransformers with identical primary and secondary windings differ from those with isolation transformers, enhancing safety and protecting against power transmission distortions.

Exploring Various Types of Isolation Transformers

Various types of isolation transformers are as follows: 

Ultra Isolation Transformer

Specifically made for eliminating the common electrical noise. The ultra-isolation transformer is structured with a unique composition. The transformer achieves this by splitting the ground area between primary and secondary, thus enhancing the isolation levels of primary and secondary networks to meet the critical applications of switch mode power supplies in fields like medical equipment, CNC machines, and digital communication systems.

Constant Voltage Transformer (CVT) 

The advantage of CVT is that it uses ferroresonant technology to maintain the output voltage despite fluctuations in input voltage. The tank circuit of the CVT consists of a high-voltage resonant winding and a capacitor, which serves as reliable protection against voltage spikes and provides a steady output voltage. The built-in regulator allows voltage adjustment for industrial applications, making it helpful in preventing voltage spikes.

Galvanic Isolation Transformer

Galvanised isolation transformers create electrical isolation between input and output power circuits, blocking ground loop interference and noise effects. Although this is the most widespread application in home computers, it guarantees safe operation and eliminates power line distortions in many applications.

Drive Isolation Transformer

Being the product of many years of practical experience, we are proud of the power transformer that separates the incoming line from the motor drive via the galvanic isolation and performs the required voltage shift. They can withstand current distortions and voltage surges typically used in motor drives, guaranteeing reliable performance in industrial settings.

Dry Isolation Transformer

Covered in a sealed container or epoxy resin, dry isolation transformers usually need little service and provide a reliable power supply. They achieve this in places where safety is highly valued, including schools, hospitals and chemical industries. The common feature of these environments is providing secure and reliable power distribution.

What is Surge Protection Device (SPD)?

SPDs, also known as TVSSs, are regarded as non-linear forward-biased zener diodes decoupling the whole system to the ground. These devices are strategically laid along the line to be safeguarded between equipment. SPDs, by contrast, do not need ratings based on the line current.

During normal supply voltage conditions, SPDs remain in a high impedance state. This advantage, under transient conditions, such as voltage surges, would cause de-rating of the line voltage above the SPD's clamping threshold. Accordingly, the SPD rapidly changes into a lower impedance condition. Moreover, some of the current aggressively spikes as an offset to the ground or the source of power. This rapid response effectively limits the transient voltage to a safe level, protecting the connected equipment from potential damage. Following the absence of transient, the SPD becomes the automatic resetting of SPD, in order to give continuous protection against future surges.

How Does a Surge Protector Work?

Surge Protection Devices (SPDs) stop transient voltage spikes and redirect excess current to the source or ground.

The functions of SPDs are as follows: 

• Operation Mechanism: SPDs incorporate at least one non-linear element, switching from the low-impedance mode to the high-impedance mode when certain conditions are met.
• Regular Operation: SPDs do not exert an influence and do not show any impact on a power system at typical operating voltages. They are in a high-impedance state.
• Transient Occurrence: The SPDs rapidly change to a low-resistance state in response to a momentary voltage surge. As a result, the current caused by the surge is shunted to the source or ground. The intention is to limit or ground the voltage to a safer level.
• Automatic Reset: Once the fault is removed, SPDs will return to a high-impedance state, providing continuity support at all times.

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Types of Surge Protection Devices

SPDs are broadly classified into two categories based on their operation principles:

• Voltage Limiting Components: These components can modify their impedance as voltages grow, which is why the high voltage transient spikes are clamped. For example, they can be represented through metal oxide Variants (MOVs) and transient voltage suppression (TVS) diodes.
• Voltage Switching Components: These components are activated once the threshold voltage is exceeded, quickly switching to a lower state. Gas discharge tubes (GDTs) and spark gaps are common examples.

The most recent SPD systems use a combination of a voltage limiting and voltage switching components, maximising the benefits and minimising the drawbacks of each component type. It provides total defence against transient voltage surges caused by lightning, switching procedures, and line faults.

Read Also - VARIOUS TYPES OF CIRCUIT PROTECTION DEVICES THAT PREVENTS FROM ELECTRICAL LOSSES

Conclusion

The isolation transformer and the Surge Protective Device are indeed the undisputed protectors of the electrical system. Isolation transformers guarantee safety, smooth the voltage, and eliminate ground loop interference. It successfully prevents the damages customarily caused by transient voltage spikes through surge protective devices. Together, they perform such functions as protecting equipment, assuring system integrity, and maximising performance.

Visit the Schneider eShop for different surge protection devices and isolated transformer models, including the APC Power-Saving Back-UPS Pro 1500 and Luminous LB600PRO UPS systems. With features like smart charging and automatic voltage regulation, ensure a continuous power supply, and an easy-to-use backup plan. Schneider eShop provides a solution that helps protect your data and keep you functioning seamlessly, even during power failures.