Protection
Transformer Differential Protection Principles
Similar to bus protections, transformers are protected by differential relays. Inter-winding faults (short circuits) and ground faults within power transformers can be detected by this protection scheme. Failure to detect these faults and quickly isolate the transformer may cause serious… Read more
Nov 01, 2012 | By Edvard Csanyi
Energy and Power
Smart and safe protective shutdown of LV system with selectivity
From the point of view of the operational safety and reliability of an entire low-voltage installation, it is usually desirable to specifically isolate the part of a system affected by a short-circuit in order to prevent spreading of the fault. Selectivity… Read more
Oct 30, 2012 | By Edvard Csanyi
Protection
Overcurrent protection of transformer (NEC 450.3)
The overcurrent protection required for transformers is consider for Protection of Transformer only. Such overcurrent protection will not necessarily protect the primary or secondary conductors or equipment connected on the secondary side of the transformer. Introduction Overcurrent protection of transformers… Read more
Oct 08, 2012 | By Jignesh Parmar
Energy and Power
Disturbances In LV Networks Due To Surges
There are two types of surge: those generated by a lightning impact and those resulting from electrical switchgear switching operations. Surges resulting from lightning strokes (see figure below) can affect all electrical installations. Consequently, they are without doubt the main… Read more
Oct 06, 2012 | By Edvard Csanyi
Energy and Power
How to Protect Capacitor Banks?
Capacitor banks are used to compensate for reactive energy absorbed by electrical system loads, and sometimes to make up filters to reduce harmonic voltage. Their role is to improve the quality of the electrical system. They may be connected in… Read more
Oct 05, 2012 | By Edvard Csanyi
Energy and Power
Definitions of Abnormal Voltage Conditions
A sag is a temporary reduction in the normal AC voltage. A momentary sag is a variation, which lasts for a period of 0.5 cycle to about 2 s usually the result of a short circuit somewhere in the power system. Instances… Read more
Oct 02, 2012 | By Edvard Csanyi
Energy and Power
What is the difference between Bonding, Grounding and Earthing?
One of the most misunderstood and confused concept is difference between Bonding, Grounding and Earthing. Bonding is more clear word compare to Grounding and Earthing, but there is a micro difference between Grounding and Earthing. Earthing and Grounding are actually… Read more
Sep 27, 2012 | By Jignesh Parmar
Energy and Power
Inspection of Ground-Fault Protection Systems
This type of protection is defined by the NEC (National Electrical Code) to ensure protection against fire on electrical power installations. To ensure protection against fire: The NEC defines the use of an RCD with very low sensitivity called GFP IEC… Read more
Sep 25, 2012 | By Edvard Csanyi
Energy and Power
Surge Protection of Electronic Equipment
Generally, power circuits have components that have large thermal capacities, which make it impossible for them to attain very high temperatures quickly except during very large or long disturbances. This requires correspondingly large surge energies. Also, the materials that constitute… Read more
Sep 22, 2012 | By Edvard Csanyi
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
