An example how to calculate voltage drop and size of electrical cable
Electrical load of 80KW, distance between source and load is 200 meters, system voltage 415V three phase, power factor is 0.8, permissible voltage drop is 5%, demand factor is 1. Cable is directed buried in… Read more
Jun 30, 2014 | jiguparmar
2 Most Common Contributing Factors In Motor Insulation Failure
The most frequent failure in electrical equipment is the degradation and breakdown (flashover) of the insulation. Electrical insulation can be liquid or solid, organic or inorganic. Organic insulation material consists of: enamels, varnishes, resins, or polymers that are applied to… Read more
Jun 25, 2014 | Edvard
Differences between disconnectors, load switches, switch disconnectors and circuit breakers
Various types of device are available for carrying out the switching and protection tasks listed under title that are specially designed to fulfill the respective requirements. The various parts of IEC 60947 (Low voltage switchgear… Read more
Jun 20, 2014 | Edvard
6 Factors Influencing Requirements for a Good Grounding System
In an industrial plant or other facility that requires a grounding system, one or more of the following must be carefully considered (refer to Figure 1 below): Limiting to definite values the voltage to earth… Read more
Jun 06, 2014 | Edvard
It can happen to experienced engineers too. Stay carefull.
The effect of electricity on the body depends on the amount of current and the length of time the body is exposed to it. The higher the current, the less time a human can survive… Read more
Jun 02, 2014 | Edvard
Main short circuit faults occurring in networks and machines
Short-circuits can be defined according to three main characteristics: They may be mechanical: breakdown of conductors or accidental electrical connection between two conductors via a foreign body such as a tool or animal; They may be… Read more
May 30, 2014 | Edvard
Generating Electricity with Combustion Turbines
There are two basic types of combustion turbines (CTs) other than the microturbines: The heavy frame industrial turbines and The aeroderivative turbines. The heavy frame systems are derived from similar models that were steam turbine… Read more
May 28, 2014 | Edvard
Arriving at the scene of a pole fire. What to do?
Utility pole fires are common and should be treated with great respect by firefighters. Pole fires are normally caused by the failure of insulators, switches, catastrophic failure of transformers or oil-filled switching equipment. Some poles… Read more
May 21, 2014 | Edvard
Case study – Improper grounding practice of computers in buildings
In a large office complex, computer errors including system crashes/reboots were happening during thunderstorms. The grounding of computer system had been carried out according to the recommendations of manufacturers. The grounding leads were insulated and terminated to an… Read more
May 14, 2014 | Edvard
Earthing (grounding) transformer – Voltages during a ground fault
Earthing Transformer or grounding transformer is the neutral grounding transformer – star connected on the primary and has an open delta on secondary. Open Delta has two terminals. A resistor is connected across these two terminals…. Read more
May 05, 2014 | Asif Eqbal
What affects the operating temperature within LV switchgear
BS EN 60439 states a maximum indoor ambient temperature of 40ºC, a maximum daily average of 35ºC and a minimum ambient of -5ºC. As a general guidance rule, the temperature within the low voltage switchgear… Read more
Apr 30, 2014 | Edvard
8 steps to begin basic circuit design
What do we need to know? Clearly, plunging into calculations of cable size is of little value unless the type of cable and its method of installation is known. This, in turn, will depend on… Read more
Apr 11, 2014 | Edvard
Which type of residual current device (RCD) to use and when?
We know how (very) important the total earth loop impedance Zs is in the reduction of shock risk. However, in TT systems where the mass of earth is part of the fault path, the maximum… Read more
Apr 09, 2014 | Edvard
Electromagnetic stresses on a busbar system and methods of reducing
When a conductor carries a current it creates a magnetic field which interacts with any other magnetic field present to produce a force. When the currents flowing in two adjacent conductors are in the same… Read more
Apr 02, 2014 | Edvard
Electrical Design Project of a Three Bed Room House (Part 2)
Continued from 1st part: Electrical Design Project of a Three Bed Room House (Part 1) All new domestic dwellings, including conversions, must either have: A fire detection and fire alarm system in accordance with the… Read more
Mar 31, 2014 | Sufi Shah Hamid Jalali
