Author name: Engr. Aneel Kumar

Most differential protection relays are current differential relays in which vector difference between the current entering the winding and current leaving the winding is used for sensing and relay operation. Differential protection principle is used I the following applications. § Protection of the generator, protection of generator transformer unit. § Protection of transformer. § Protection […]

Differential protection is based on the fact that any fault within electrical equipment would cause the current entering it, to be different, from that leaving it. Thus, we can compare the two currents either in magnitude or in phase or both and issue a trip output if the difference exceeds a predetermined set value. This

Following are the minimum information and Data which to be shown on a transformer nameplate. The standards require the following information and data for transformers rated above 500 kVA. • Name of manufacturer • Serial number • year of manufacture • Number of phases • kVA or MVA rating • Frequency • Voltage ratings. •

As the size and capacity of the transformer increased, the associated cooling arrangement become more powerful and sophisticated. So, by definition, the transformer cooling system is such arrangement for power transformers, which limits the generated heat into a safe value by means of proper dissipation of generated heat. Different cooling system is used for different

The electrical winding and the magnetic core in a transformer are subject to a number of different forces during operation, for example. a) Expansion and contraction due to thermal cycling.b) Vibration.c) Local heating due to magnetic flux.d) Impact forces due to through fault current.e) Excessive heating over loading or inadequate cooling. These forces can cause

The main principle of operation of a transformer is mutual inductance between two circuits which is linked by a common magnetic flux. A basic transformer consists of two coils that are electrically separate and inductive, but are magnetically linked through a path of reluctance. The working principle of the transformer can be understood from the

There are three main parts of a power transformer. 1. Primary winding of transformer – which produces magnetic flux when it is connected to electrical source. 2. Magnetic Core of transformer – the magnetic flux produced by the primary winding, will pass through this low reluctance path linked with secondary winding and creates a closed

Power transformers need to be protected from damages caused by internal and external faults. Power transformer can be protected from the internal faults by Differential Relay. This task is performed by relay protection which detects the fault situation and gives command to the relevant circuit breaker(s) to disconnect the faulty equipment from the rest of

Two types of faults occur in power transformer i.e. external and internal electrical faults.External Faults in Power Transformer: (a) External Short – Circuit of Power Transformer: The short – circuit may occur in two or three phases of electrical power system. The level of fault current is always high enough. It depends upon the voltage

POWER TRANSFORMER “A Power transformer is a static machine used for transforming power from one circuit to another circuit without changing Power and frequency”. Power transformers used between the generator and the distribution circuits, and these are usually rated at 500 KVA and above. Power systems typically consist of a large number of generation locations,