Difference Between Isolation Transformer and Regular Transformer

Quiz

An electrical transformer is one of the most widely used electrical machines in power system. The main function of a transformer is to change the voltage levels in the system for different purposes. Depending on the purpose, these transformers can be classified into different types like step-up transformer, step-down transformer, or isolation transformer.

The step-up or step-down transformers can also be referred to as regular transformers. These are used for changing the level of supply voltage. On the other hand, an isolation transformer is used for providing an electrical separation between the input and output circuits.

The most fundamental difference between an isolation transformer and a regular transformer is that an isolation transformer is used for providing electrical isolation/separation between input and output circuits while a regular transformer is used for changing the voltage levels in the system.

In this article, we will explain all the important differences between regular transformers and isolation transformers along with their basics, purposes, and advantages. So, lets start with the basics of a regular transformer.

What is a Regular Transformer?

A regular transformer, normally referred to as an electrical transformer or just transformer, is an electrical machine used for transferring electrical energy from one circuit to another through electromagnetic induction with a change in supply voltage. Therefore, a regular transformer is used for either increasing or decreasing the supply voltage to meet the requirements of the load connected.

These transformers can be classified into two types namely, step-down transformer and step-up transformer as shown in the following figure.

For a step-down transformer,

$$\mathrm{V_{1} \: \gt \:V_{2}}$$

$$\mathrm{N_{1} \: \gt \:N_{2}}$$

For a step-up transformer,

$$\mathrm{V_{1}\:\lt \:V_{2}}$$

$$\mathrm{N_{1}\:\lt \:N_{2}}$$

Where, V₁ is the input voltage, V₂ is the output voltage, N₁ is the primary winding turns, and N₂ is the secondary winding turns.

Regular transformers are extensively used in generating stations, transmission systems, and distribution systems for supplying electrical power to the end consumers.

What is an Isolation Transformer?

An isolation transformer is simply an electrical transformer which is used for providing electrical separation between the input and output circuits of the electrical system. This transformer typically has equal number turns in both primary and secondary windings i.e.,

$$\mathrm{N_1 \: = \: N_2}$$

Therefore, the primary and secondary voltages are also equal i.e.,

$$\mathrm{V_1 \: = \: V_2}$$

Electrical separation is provided in electrical systems for protecting them from unwanted power surges, transients, and noise and improve the reliability and efficiency of the system.

An isolation transformer separates the input and output circuits electrically, but it couples them magnetically. Since an isolation transformer has the same number of primary and secondary winding turns, it is also called as a 1:1 transformer. In this type of electrical transformer, a high-grade insulation material is used for providing effective electrical isolation between the primary and secondary windings.

Isolation transformers are primarily used in sensitive electrical systems like telecommunication systems, medical equipment, industrial control systems, etc.

Difference Between Regular Transformer and Isolation Transformer

The following table highlights all the significant differences between regular transformer and isolation transformer

Parameter	Regular Transformer	Isolation Transformer
Purpose	A regular transformer is used for changing (increasing or decreasing) the voltage levels in a system.	An isolation transformer is used for providing electrical isolation between input and output circuits.
Types	A regular transformer can be of two types namely, step-up or step-down.	There is no such classification of isolation transformer.
Design consideration	A regular transformer is designed for effective voltage transformation without much concerning about isolation.	Isolation transformers are designed to have a high degree of electrical isolation between primary and secondary windings.
Number of turns	A regular transformer can have either $\mathrm{N_1\:\gt \:N_2\:or\:N_1\:\lt \:N_2.}$	An isolation transformer typically has an equal number of turns in both windings i.e., $\mathrm{N_1\:=\:N_2.}$
Input and output voltages	A regular transformer can have voltages as $\mathrm{V_1\:\lt \:V_2\:or\:V_1\:\gt \:V_2.}$	An isolation transformer typically has voltages as $\mathrm{V_1\:=\:V_2.}$
Power rating	Regular transformers can have any power rating depending on the requirements of the application.	Isolation transformers generally have small power ratings.
Shielding against EMI	Regular transformers are not effective in reducing the electromagnetic interference.	Isolation transformers are designed to provide protection against electromagnetic interference.
Physical size	The size of a regular transformer depends on its power rating.	Isolation transformers usually have a smaller physical size.
Suppression of harmonics	Regular transformers usually do not have harmonics suppression capabilities.	Isolation transformers can reduce harmonics effectively.
Efficiency	Regular transformers are less efficient.	Isolation transformers are more efficient than regular transformers.
Energy loss inside the transformer	Regular transformers have more energy loss inside them.	Isolation transformers have lower energy losses inside them.
Initial cost	Regular transformers are less expensive to purchase.	Isolation transformers are more expensive due to specialized design.
Operational cost	Regular transformers have high operational cost due to lower efficiency.	Isolation transformers have low operational cost.
Applications	Regular transformers are commonly used in power systems for transmission and distribution of electrical power at different voltage levels.	Isolation transformers are used in telecommunication systems, medical equipment, industrial automation, etc. for providing electrical isolation.

Conclusion

From the above comparison, we can conclude that the operating principle of both transformers is the same i.e., electromagnetic induction. But an isolation transformer is specially designed to provide complete electrical separation between input and output circuits, while a regular transformer is designed for voltage transformation.

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