Transformers are electrical devices with the main function of transforming the energy from the primary to the secondary side. Means of the transformer core magnetic field are used to transform the energy with equal frequency and approximately equal power. Therefore, galvanic isolation is provided in the electrical system. The isolation transformers have the same operation way as other transformer types. But they are mainly used to provide galvanic isolation in the electrical system. They can work as step-down transformers or step-up transformers but often operate with a turns ratio. This means that the primary value is equal to the second voltage value. Therefore, the number of turns on the primary obtained is equal to secondary windings.
The isolation transformers are used in many electrical devices like computers, measurement devices, or specific industry power electronic devices.
Isolating transformers play an important role in the case when an oscilloscope measures signals in an electrical circuit that is not galvanically isolated from the network. Because it is possible to close the current circuit closed (short-circuited) between oscilloscope common point and grounding. The main purpose of the isolation transformer is safety and protect electronic components and persons against electrical shock. It physically separates the power supply from the primary side and a secondary side circuit linked to electronic components and grounded metal parts that are in contact with the person. Basically, the secondary side of the transformer is isolated from the grounding.
This means that the secondary side of the isolation transformer must not be grounded. A physical connection will be created between the primary and secondary transformer sides. The autotransformer with common winding has a connection between the primary and secondary sides, thus it can not be used as an isolation transformer. Even if the device is broken, an isolation transformer provides an available supply. The primary side remains under-voltage which can be used to supply some alarm or warning beep circuits even if the device is broken.
The transformers suppress the electrical noise from electromagnetic induction or supply. That plays a very essential role in the case of sensitive devices as measurement or medical devices. This transformer is built with electrostatic shields which additionally increase the electrical noise suppression. The proper isolation transformer is designed to avoid ground loops. An additional current path is created by Ground loops where the current created by electromagnetic induction can flow. This is the main cause of noise and interference in the signal.
For the isolation transformer design, it is very important to pay attention to windings capacitance values which create capacitive coupling. AC signal is allowed to pass from the primary to the secondary side which significantly increased the noise level. For this purpose, the windings are surrounded by a grounded metal strip (creating a Faraday shield).
The isolation transformers are used as instrument transformers when It is necessary to measure the high voltage. Measuring the high voltage is dangerous for the person but it can also harm the measurement circuits. In this case, the step-down isolation transformer has the function of reducing the high voltage to the safe level and for measurement range.
Application of Isolation Transformer
1. The Isolation Transformer is mainly used to make the isolation between a power supply and a powered circuit or powered device for safety purposes.
2. Isolation transformers can be used as Pulse Transformers.
3. Isolation Transformer is used to transform electrical power between two circuits that are not connected electrically to each other. Those two circuits are may have the same voltage level or different voltage levels.
4. Sometimes the Isolation Transformer is used in electrical circuits as well as an electronic circuit to provide protection against Electrical shock.
5. Isolation transformers are used for computer network design. Here isolation transformers act as Pulse Transformers.
6. Isolation Transformer is used to block ground loop interference in a circuit.
7. Isolation transformers are also used in electronic circuits as well as electrical circuits and some sensitive devices to reduce electrical noise.
8. The isolation transformer is used in power supply circuits in sensitive devices such as Computer, Oscilloscope, Medical Devices
9. Isolation transformers are used in communication circuits and Radars.
10. Isolations Transformers are used in electrical and electronic testing devices.