Mechanical factors of safety to be used in transmission line design should depend to some extent on the importance of continuity of operation in the line under consideration. In general, the strength of the line should be such as to provide against the worst probable weather conditions. We now discuss
Month: December 2014
The electric power system in general is 3-phase a.c. operating at a frequency of 50 Hz. The power station delivers power to consumers through its transmission and distribution systems. The power delivered must be characterized by constant or nearly constant voltage, dependability of service, balanced voltage, efficiency so as to
A device which taps electrical energy from the electric power system is called a load on the system. The load may be resistive (e.g., electric lamp), inductive (e.g., induction motor), capacitive or some combination of them. The various types of loads on the power system are: (I) DOMESTIC LOAD Domestic
There are perhaps four distinct categories of wind power which should be discussed. These are 1. small, non-grid connected2. small, grid connected3. large, non-grid connected4. large, grid connected By small, we mean a size appropriate for an individual to own, up to a few tens of kilowatts. Large fers to
Dynamic Voltage Restorer is a series connected device that injects voltage into the system in order to regulate the load side voltage. The DVR was first installed in 1996. It is normally installed in a distribution system between the supply and the critical load feeder. Its primary function is to
1) TAP CHANGING TRANSFORMERS Electronic tap changing is achieved via the use of back to back thyristors (SCR) with a tap changing transformer. Has a reasonable response time (1 cycle) and is popular for medium power applications (>3kVA). However, high control resolution requires large number of SCRs. the control for
SOURCES OF UNBALANCE Unbalance may generate due to the unequal drops in individual phase or unbalanced in three phase loading. Even it may happen due the source, load, improper grounding, etc. The main causes of voltage due to unbalance in power systems are • Unbalanced single-phase loading in a three-phase
An online UPS accepts input power with relatively wide variations in voltage and frequency, a common occurrence in power produced by standby generators. The true on-line (double conversion) technology provided by an on-line UPS handles these variations by converting the input power from AC to DC and then converting DC
• SPDs should be installed with the shortest lead length possible and as close as possible to the load it is protecting. • SPDs protecting panels should be wired in parallel with the service entrance or distribution panels. A disconnecting means must be provided for servicing and for short circuit
Poor power quality is characterized by electrical disturbances, such as transients, surges, sags, power interruptions and harmonics. The disturbances can originate externally without warning, but are often generated within your facility. Eighty percent of electrical disturbances that cause poor power quality come from within your facility. Powering on and off