Tricky but Easy Electrical Engineering!
Transformer Overflux Protection is provided to protect the Transformer core from overfluxing. A Transformer is designed to operate at a particular flux level. In case the flux in the core of Transformer exceeds a certain level, the core loss increases which may lead to overheating of components which in turn may result into internal fault. … Read more
If you get a chance to visit any substation or Switchyard, you will notice that the surface of the Switchyard is fully covered with small size Gravels. The use of gravels on the surface has the following things to do: Although Substation / Switchyard grounding is very low in the range of 0.5 to 5 … Read more
Step potential is the voltage between the feet i.e. one step of a person standing near an energized grounded object. Touch potential is the touch voltage between the energized object and the feet of a person in contact with the object. It is equal to the difference in voltage between the object and a point … Read more
To understand this aspect making current and breaking current, first we should know what actually the making current and breaking current signifies in context with Circuit Breaker. Making Current of a Circuit Breaker is the peak value of maximum current loop during subtransient condition including DC component when Breaker closes. In the figure below, I1 … Read more
MCB stands for Miniature Circuit Breaker which is widely used in home and industries. A Miniature Circuit Breaker (MCB) is a small circuit breaker that is used for residential and industrial applications. As every circuit breaker, it has both a switching function (it allows the connection / disconnection of the circuit where it is installed) … Read more
A Transmission Line classification based on its length are Short, Medium and Long lines. The length of line is calculated between the two substations of concern. If the length of line is less than 80 km then it is said to be Short Transmission Line. The length of Medium Transmission Line varies from 80 to 160 km. … Read more
In this post we will discuss about the feature of Harmonic Restraining feature of Differential Protection. First we should know why Harmonic Restraining is needed? Suppose we are going to energize the Transformer, obviously the Transformer will have an Inrush current which is around 6 times of full load current. Refer “Transformer Inrush Current” for … Read more
As discussed in the post “Transformer Differential Protection”, differential protection is supposed to operate for the internal faults or for the zone of protection it is intended for. Differential protection is not supposed to operate for a through fault. Through fault means a fault outside the zone of protection. Thus as discussed in earlier post, … Read more
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
For the purpose of quality assurance and ensuring that the finished transformer conforms to customer requirements and is ready for service a barrage of tests are performed on the transformer. These can be broadly classified into the following 3 types: Routine Test, Type Test and Special Test. 1) Routine Tests: These are standard tests performed … Read more