Energy and Power
Introduction to Static Protection Relays
The term ‘static’ implies that the relay has no moving parts. This is not strictly the case for a static relay, as the output contacts are still generally attracted armature relays. In a protection relay, the term ‘static’ refers to… Read more
Sep 21, 2012 | By Edvard Csanyi
Energy and Power
What is the purpose of equipotential bonding?
Equipotential bonding is essentially an electrical connection maintaining various exposed conductive parts and extraneous conductive parts at substantially the same potential. An earthed equipotential zone is one within which exposed conductive parts and extraneous conductive parts are maintained at substantially… Read more
Sep 20, 2012 | By Edvard Csanyi
Energy and Power
Functions Performed by Electrical Switchgear
National and international standards define the method for making electrical distribution circuits as well as the purpose and functions of switchgear. There are three main functions, namely: Circuit protection takes three main fault types into account: Overloads, Short-circuits (Both of which… Read more
Sep 14, 2012 | By Edvard Csanyi
Protection
Transformer differential protection (ANSI 87T)
Transformer differential protection protects against short-circuits between turns of a winding and between windings that correspond to phase-to-phase or three-phase type short-circuits. If there is no earthing connection at the transformer location point, this protection can also be used to… Read more
Sep 05, 2012 | By Edvard Csanyi
Electric Motor
Motor protection depending on size and voltage level
Motor protections vary widely depending on the size of the motor and voltage level involved, thus only the more common ones are discussed in this technical article. Index Motor Instantaneous Over-current Protection Motor Timed Over-Current Protection Thermal OverLoad Motor Ground… Read more
Aug 30, 2012 | By Edvard Csanyi
Energy and Power
High resistance grounding equipment in mining applications
High resistance grounding equipment or permanently installed electrical distribution systems used in mines should be selected and applied as recommended for process industries. When mobile equipment is connected to the distribution system the grounding equipment and the ground fault protection should be designed… Read more
Aug 22, 2012 | By Edvard Csanyi
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
