Isolation Transformers: Working and Important Applications

Isolation transformers serve the galvanic isolation in electrical systems by isolating the circuits supply and and secondary side. In single phase electrical wiring, there are three wires hot, neutral, and ground. When there are numerous physically separated devices are connected in the same circuit they may use a similar power line. Hence there may form grounding loops which are connected to different devices but connected to the same grounding. Now, these ground loops are particularly problematic.

When we talk about medical equipment as they are more sensitive equipment. Therefore the leakage currents produced by these grounding loops may disrupt the device during testing. So, it is hard for the designers to meter these these grounding loops with the apparatus that uses rectifier circuitry. As these grounding loops may also cause the noise problems in power lines. Which eventually may damage the electronic circuits connected to power lines.

Above described issues can be catered by using the isolation transformers in the circuits which are critical in nature. These isolation transformers serve the isolation features between the input of power supply and the equipment circuitry itself.

Therefore in any case if there is any surge or voltage spike on the input side, it may be blocked on the input side. Hence it saves the equipment circuitry from damage. In other words it also acts as a protection against the high frequency noise which may ride on power supply if power supply ground and equipment circuitry ground is common. Isolation transformers act as a separation in circuitry.

Isolation Transformer Diagram

Below is isolation transformer diagram in which we can see the primary and secondary winding on the core.

How Isolation Transformers Work?

Isolation transformers are the electrical devices which have two winding as traditional transformers , primary and secondary. These two windings are isolated physically and electrically which means they don’t have a direct electrical connection. Now the transfer of energy from primary to secondary winding happens through magnetic induction. The transmission of electrical energy happens due to generation of EMF by magnetic induction. Hence in this transmission of energy, frequency of the supply doesn’t vary.

An isolation transformer is a stationary device with isolated primary and secondary windings that keeps the two circuits separated, physically and electrically. It transmits electrical energy between circuits by incorporating a magnetic induction mechanism that uses a magnetic field to generate EMF in another circuit without affecting the frequency.

Isolation transformers working is based on the electromagnetic induction. Alternating current flows through the primary circuit. It generates a varying magnetic field within the core of the transformer. This varying magnetic field then induces the EMF in the secondary circuit. Therefore, we get the desired output voltage.

Main feature of isolation transformers is that they create a physical separation between the primary and secondary circuits. They ensure there is no direct electrical connection between them. This isolation is really important in situations where Equipment shielding from electrical disturbances which may include noise, leakage current or electrical interference is necessary.

For example, in photovoltaic installations we see  isolation transformers applications are numerous. They are employed for safety of personnel and equipment. Through isolation we can minimize the risk of fire and electrical damage. Hence we can ensure operational safety.

Why we Use Isolation Transformers

Isolation transformers are utilized in electrical circuits for Electrical isolation. This isolation is in between the input and output circuits. This is physically separation of the input winding from the output winding. This is how they prevent direct electrical connection between the two windings. Now we will elaborate some key reasons of why isolation transformers are used:-

Safety:-  Isolation transformers help in protection of people from electric shocks. As the the grounding isolate, the input and output circuits also isolate. This aspect has specific importance where there is a risk of high voltage spikes or leakage currents In the circuits.

In above picture we can see a person touching the equipment through isolation transformer. If person is not wearing the shoes then he will get a shock as there will be a current path to the ground. But if he is wearing shoes then he will get a minor jerk from electric equipment. If there is any short circuit in the equipment then all short circuit current must go to the ground. For that secondary side of the isolation transformer should be grounded also. let’s have a look at below picture:

In above picture we can see in first scenario, the person and the equipment ground makes the same current path. This scenario is without isolation transformer. Below scenario is along with isolation transformer and we see the grounding point is different and hence personnel remain on safety side.

Noise Reduction:- Isolation transformers are equally important in reduction of noise in circuits. Which includes both common mode and differential mode noise in electrical systems. Common mode noise is the noise which appears at the same time on both the line and neutral conductors. While on the other hand differential mode noise appears in between the line conductor and neutral conductors.

In this way, by isolating the input and output circuits, isolation transformers prevent noise from being transferred between them. Which eventually leads to the cleaner power. And hence  improved performance of sensitive equipment.

Ground Loop Elimination:-  Isolation transformers can also help in elimination of  ground loops. Ground loops can be generated when there are multiple paths to ground in an electrical systems. These Ground loops can cause unwanted noise. And also interference in audio and video systems. By isolating the grounding  connection between the input and output circuits, isolation transformers can avoid formation of grounding loops.

Voltage Regulation:- In many applications when we use isolation transformers, and there is a sudden voltage spike which stays for a very shorter period of time. This voltage surge may not transfer on the secondary circuit due to the shorter time duration. Therefore we can say that isolation transformers may help in voltage regulation. They help in regulate voltages when input voltage fluctuates.

Signal Isolation:- Isolation transformers are commonly employed in applications where electrical signals need to be transmitted. These signals may distort during transmission or may interfere with other components in the circuits. Therefore isolation transformers are used in those circuits to isolate telecommunication signals from power circuits.

For example; in the audio and telecommunications systems; isolation transformers can help prevent signal distortion and interference.

Worth Read Posts

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2. Power Transformer Parts
3. Hysteresis Loss and Eddy Current Loss
4. Derivation of Hysteresis Losses
5. Transformers: Important Types, Features & Components
6. Transformer Tests Before Commissioning
7. Transformer Electrical Interview

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