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 individual power outputs, and the relatively short distances in industrial and building power systems mean …
Inspection of voltage drop in conductors
It is part of the inspection process to ensure that installed conductors have been correctly selected for current carrying capacity and voltage drop. To check the suitability of the current carrying capacity it is simply a matter of looking at the installation method, and then checking on the current carrying capacity tables for the cable …
What is incident energy caused by arc flash?
Incident energy is the energy per unit area received on a surface located a working distance away from the arc flash location. The working distance is the distance from where the worker to the flash location. This is basically an arm length away or approximately 18 inches for low voltage panelboards, smaller equipment, and 24 …
Key Cyber Security Purposes for the Smart Grid
In the Smart Grid, there are two key purposes for cyber security: Power system reliability Keep electricity flowing to customers, businesses, and industry. For decades, the power system industry has been developing extensive and sophisticated systems and equipment to avoid or shorten power system outages. In fact, power system operations have been termed the largest …
Star-Delta Motor Starter
Introduction to Star-Delta motor starter Most induction motors are started directly on line, but when very large motors are started that way, they cause a disturbance of voltage on the supply lines due to large starting current surges. To limit the starting current surge, large induction motors are started at reduced voltage and then have …
Short review of resistance, reactance and impedance
Resistance, R Resistance is essentially friction against the motion of electrons. It is present in all conductors to some extent (except superconductors!), most notably in resistors. When alternating current goes through a resistance, a voltage drop is produced that is in-phase with the current. Resistance is mathematically symbolized by the letter “R” and is measured …
The direct current (DC) motor – Principle of operation
DC motors have been used in industrial applications for years. Coupled with a DC drive, DC motors provide very precise control DC motors can be used with conveyors, elevators, extruders, marine applications, material handling, paper, plastics, rubber, steel, and textile applications to name a few. The basic construction of a DC motor is shown in …
Erection Procedures For Medium Voltage Switchgear
Before commencing erection of medium voltage (MV) switchgear check that all connections are tight on busbars and on main and auxiliary circuits. Examine the insulation carefully, because there have been cases of burned out connections due to failure to observe this precaution. Obvious faults such as distorted panel work, broken meter glass and damaged packing …
Single-Phase Power vs Three-Phase Power
The principal elements of an electric power system are the generating stations, the transmission lines, the substations, and the distribution networks. The generators produce the electricity, the transmission lines move it to regions where it is consumed, and the substations transform it for industrial, commercial, and residential use. Finally, the distribution networks carry the electricity …
Architectural Luminaires – Unusual Visual Effects
Architectural luminaires are custom-designed and built fixtures that offer features not available in commercial luminaires. They can be built to fit specific locations or perform desired functions as well as provide unusual visual effects. These luminaires can be made from wood, metal, or plastic decorative elements and they can include standard lamp sockets, lampholders, wiring, …
