Protection
Protecting Oil Type Transformer with Buchholz Relay
Buchholz relay is a gas-actuated relay installed in oil immersed transformers for protection against all kinds of faults. Named afteri ts inventor mr. Max Buchholz (1875–1956) in 1921, relay is used to produce an alarm in case of incipient (i.e.slow-developing) faults… Read more
Aug 16, 2012 | By Edvard Csanyi
Protection
Delayed Auto-Reclosing On EHV Systems
On highly interconnected transmission systems, where the loss of a single line is unlikely to cause two sections of the system to drift apart significantly and lose synchronism, delayed auto-reclosing can be employed. Dead times of the order of 5s-60s are commonly used…. Read more
Aug 11, 2012 | By Edvard Csanyi
Energy and Power
Principles of Transformers in Parallel Connection
For supplying a load in excess of the rating of an existing transformer, two or more transformers may be connected in parallel with the existing transformer. The transformers are connected in parallel when load on one of the transformers is… Read more
Aug 06, 2012 | By Jignesh Parmar
Cables
Sizing and protection of the neutral conductor (2)
Continued from the first part – Sizing and Protection of the Neutral Conductor (1) If the neutral conductor is correctly sized (including harmonics), no specific protection of the neutral conductor is required because it is protected by the phase protection. If… Read more
Jul 31, 2012 | By Edvard Csanyi
Energy and Power
Overvoltages in the IT system
Electrical networks can be subject to overvoltages of varying origins. Some overvoltages, such as differential mode ones (between live conductors) affect all the earthing systems. This section is particularly concerned with common mode overvoltages, which mainly affect the IT system… Read more
Jul 26, 2012 | By Edvard Csanyi
Energy and Power
Isolating the Fault With Time-based Discrimination
Protection functions form a consistent system depending on the overall structure of the power distribution system and the neutral earthing arrangement. They should therefore be viewed as a system based on the principle of discrimination, which consists of isolating the… Read more
Jul 22, 2012 | By Edvard Csanyi
Energy and Power
Effect of Lightning Strike on Electrical Lines
The foregoing discussion concentrated on the principles of lightning strikes and how their effects can be mitigated. However, lightning strikes on electrical lines or substations are those that cause problems in the distribution network which come right into our residences… Read more
Jul 20, 2012 | By Edvard Csanyi
Electric Motor
Thermal (Overload) Motor Relay Protection
The majority of winding failures in motor are either indirectly or directly caused by overloading (either prolonged or cyclic), operation on unbalanced supply voltage, or single phasing, which all lead through excessive heating to the deterioration of the winding insulation… Read more
Jul 14, 2012 | By Edvard Csanyi
Energy and Power
Delta-Star Transformer Connection Overview
The Delta-Star transformer connection is utilized to increase voltage levels and is frequently applied at the end or beginning of high-tension power transmission systems. The primary is configured in a delta arrangement, while the secondary is arranged in a star… Read more
Jul 10, 2012 | By Jignesh Parmar
Energy and Power
MCB – Miniature Circuit Breaker Construction
The miniature circuit breaker (MCB) plays an important role in providing overcurrent protection and a disconnect means in electrical networks. Recent advancements in circuit breaker technology has increased breaker performance and protection. A breaker is a device designed to isolate a circuit… Read more
Jun 07, 2012 | By Edvard Csanyi
Electrical Lectures
Understanding Vector Group of Transformer (Part 1)
Three phase transformer consists of three sets of primary windings, one for each phase, and three sets of secondary windings wound on the same iron core. The vector group of the transformer is determined by the connection between the windings… Read more
Jun 03, 2012 | By Jignesh Parmar
Electric Motor
Direct On Line (DOL) Motor Starter
Different starting methods are employed for starting induction motors because Induction Motor draws more starting current during starting. We use a variety of starters in order to protect the windings from being damaged by the high current flow that is… Read more
Apr 22, 2012 | By Jignesh Parmar
Energy and Power
System protection and safety coordination definitions
The objective of system protection is to detect faults and to selectively isolate faulted parts of the system. It must also permit short clearance times to limit the fault power and the effect of arcing faults. High power density, high… Read more
Apr 16, 2012 | By Edvard Csanyi
Electric Motor
Star-delta motor starter explained in details
Where is Star-Delta motor starter used? Well, the majority of induction motors are started directly on line (DOL), but when very big motors are started in this manner, the large starting current surges produce a disruption in the voltage on… Read more
Apr 10, 2012 | By Jignesh Parmar
High Voltage
Protection and Relays Used In Main Circuit Board at a Power Grid Substation
The DMH type relay provides high speed biased differential protection for two or three winding transformers. The relay is immune to high inrush current and has a high degree of stability against through faults. It requires a max of two… Read more
Feb 17, 2012 | By Bipul Raman
