Transformers with time have progressed into an era where their importance cannot be ignored at any instance. New processes and equipment are in use by the various industries in diverse domains. Technology has proven to be a boon for such equipment which has transformed the outlook of the electrical industry. These are expensive and vital components of the power systems. New ways and mechanism are in place to avoid any damage to the different equipment in use and to provide equal and stable distribution of power in an effective and efficient way.

Role of tap changer :

The role of a tap changer used in transformers is being highly recognized in industries around the world. This type of device is designed to support the power transformer which regulate the final output voltage to the desired intensity. The requirements vary from one source to the other which is why this is being enforced to ideally alter the number of turns in the winding so as to meet the demands. With on load tap changer the supply voltage is controlled within the limits in a variable manner. This specialization is nowadays being accepted and appreciated by almost all to maintain the voltage regulation.

Basic Types :

On the basis of operation, the tap changers are distinguished as:
  • On load tap changers are types which come into effect when the transformers are on load. This requires a make before break technique where these are motor driven and has the option to be used automatically or manually.
  • Off load tap changers are devices utilized in cases where the transformers are kept disconnected and does not require a make-before-break system.
  • With on load tap changer the potential of the transformers has experienced a new development. This has minimized the requirement for maintenance of the power equipment and created an environmental friendly platform. Such a technique offers solutions in the form of:
  • Power flow regulation
  • Regulation of voltage for high power transformers
  • Protection of transformer failures
  • Power grid analysis

Prominent Features

  • Minimal noise
  • Offers standard electrostatic shield
  • Standard neutral
  • Effective coupling capacitance
  • Impedance prevents short circuits of the tapped portion
  • Unsurpassed simplicity
  • Convenient accessibility
  • Low failure rates
  • Cost effective

On load tap changer operation

In a normal scenario the voltage of a transformer may not match the exact voltage requirement of a system. In such cases the use of on load tap changer comes into the picture wherein this technique assists in raising or lowering the output voltage to the desired load. The operation is based on the switching principle where the number of windings is added or removed accordingly to attain the desired output. This can be fixed in any one location of the entire transmission line which depends on the winding type. The possibilities are:
  • At the star point
  • Middle of the winding
  • End of the winding
The consideration is checked on the basis of the stress factor. In most cases the arrangement is done in the middle or at the end to provide least electrical stress. Thus with on load tap changers the tapping on different energized transformer windings are adjusted without the need of any specialized tools.

The tap changers have become an indispensable component in today's electrical networks and industrial applications in a large scale.

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