Transformer Off-Load Tap Changer

Taps are connections to the, usually high-voltage winding of a transformer which enables changes to the turns ratio to be made in order to make changes to the secondary voltage to compensate, where necessary, to a fall in terminal voltage below the regulatory allowance. There are two types of tap-changing mechanism, ‘Off-Load Tap Changer’ and … Read more

Concept of Tap-Changers in Transformer

The modern loads are designed to operate at satisfactorily at one voltage level. It is therefore of great importance to keep the consumers terminal voltage within a prescribed limits. The Transformers output voltage and hence the terminal voltage of the consumer can be controlled by using tap either on primary or secondary side of Transformer. … Read more

Dry Type Transformers versus Oil Filled Transformers

Before going to the mark difference between Dry Type Transformer and Oil Filled Transformer, it is worth to have some discussion on Dry Type Transformer. Dry Type Transformer: Dry Type Transformers find use in locations where the use oil Filled Transformers increases the fire hazard such as shopping malls, Hospitals, residential complexes etc. In dry … Read more

Why Core Type Transformer is widely used than Shell Type?

The core type transformers have many advantages over shell type transformers as follows: The core is greater than shell  but the circular coils that are used are easier to wind. Provide more mechanical strength especially when short circuit occurs. High space factor and reduced mean length of turns resulting in reduced copper losses. Longer mean … Read more

Buchholz Relay – Construction and Working Principle

Buchholz relay is a gas actuated protection relay which is generally used in large oil immersed transformers of rating more than 500 kVA. It is used for the protection of a Transformer from the faults occurring inside the transformer. A typical Buchhloz Relay is shown below.   The gas actuated protective relay is designed to … Read more

SFRA Test of Transformer

SFRA stands for Sweep Frequency Response Analysis. This test is very reliable for condition monitoring of physical condition of transformer winding, core and above all core & winding integrity. Why to conduct SFRA test? The winding of Transformer may be subjected to mechanical stresses during transportation, heavy short circuit faults, transient switching impulses & lightening impulses etc. … Read more

Transformer Inrush Current

In this post we will discuss the Magnetizing Inrush Current in a Power Transformer. Magnetizing Inrush urrent in Transformers results from any abrupt changes of the magnetizing voltage. This current in transformer may be caused by energizing an unloaded transformer, occurrence of an external fault, voltage recovery after clearing an external fault and out-of phase … Read more