Tap Changer Accessories

In a transformer, there would be certain connection points along the winding that allow for the selection of a particular number of turns. These are known as transformer taps. As a result of this, the transformer now has a variable turns ratio, and this in turn makes way for the regulation of voltage of the output. The tap selection of the transformer is made using the mechanism of tap changers.

There are various tap changers that work on different mechanisms and are put to use in different scenarios.

Off-circuit Design Tap Changer Accessories

In transformers that are low voltage, low power, it is possible for the tap point to be a connection terminal that needs disconnection of the power lead and connection to a new terminal to happen manually. It is not possible to make two or more connections simultaneously, in order to avoid the possibility of a short-circuit. This means that during manual switchover, the power supply will be interrupted. An off-circuit tap changer accessory is usually set only once during installation. If any adjustments for long-term changes in the voltage profile of the system need to be changed, then the tap changer mechanism may be altered in such a scenario.

On-load Design Tap Changer Accessories

Sometimes, for certain types of applications, the interruptions in power supply is not acceptable. In such a case, on-load tap changer accessories are made use of. Such accessories are usually more complex as well as expensive. There are three different types of on-load tap changers.

• Mechanical Tap Changer Accessories: These tap changers basically make use of several switches to make a new connection prior to          releasing the old, thereby not interrupting the power. A diverter switch is also used to prevent the creation of high circulating currents.      
• Thyristor-assisted Tap Changer Accessories: As the name suggests, thyristors are made use of to take on the on-load current during the time when the main contacts are changing from one tap to the next. A service life of longer duration results, due to the prevention of arcing on the main contacts. However, these can be more expensive and are more complex, requiring low voltage power supply. These are otherwise known as electronically assisted tap changers.
• Solid State/Thyristor Tap Changer Accessories: In these devices, thyristors are used for two functions: the switching of the load current as well as the steady state passing of the load current. This type of tap changer is more recent when compared to the other two. However, the withstand capacity of these accessories to short circuit is smaller in comparison. Hence, they are used more often on smaller power transformers. These are also known as electronic tap changers.

There are several websites on the internet that sell electrical and electronics products online. Also, many websites list the products manufactured and sold by their companies as well as detailed, in-depth information about these products. Tap changer accessories can easily be found on such websites. Some such websites are abb.com, ferrantitapchangers.com, tdproducts.com, and so on.