Friday, December 14, 2012

Wide Range of Whitepapers

Do you want some additional information on any Electrical Subject? You may require information regarding some of the subjects at work, school or club. Don't wait just visit the link below to find plenty of white papers on any subject. The following are some of the topics covered in whitepapers offered by Schneider Electric.

Data centre overview papers
Data centre planning papers
Power fundamentals papers
Cooling fundamentals papers
Power best practices papers
Cooling best practices papers
Management systems best practices papers
High density papers
Energy efficiency papers

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Wednesday, June 20, 2012

Fuse Unit

Fuse unit is used to control distribution feeders. Normally fuses are provided on all the three phases. This gives over current protection and short circuit protection. These fuses are commonly used in distribution transformers to protect the lines.

Fuse Unit

Above is a typical fuse unit mounted near a transformer. This provides protection and control of the lines. Technicians can remove the fuse to a particular line and carry out the maintenance works. Also this provides a protection for over current supply and short circuit current. Fuses will blow off during over current and short circuit current.

Fuses are made of porcelain and the conducting parts are copper. Graded alloy wires are used for re-wire able fuse links. Sometimes HRC fuses are used to link between terminals. Technicians use a hand gloves while handling these fuses. It is very convenient to test the supply by using line tester.

Wednesday, June 13, 2012

How to apply for entry level electrical engineering jobs

Entry level electrical engineering jobs are available in plenty and reserved for fresh Electrical engineers just out of their college. Students studying engineering must have an idea about the opportunities available in the job market. So they study with some sort of specific ambitions in mind. They undergo specialization and carry out projects in this specific subject where they want to grab a job. By the time they complete their degree they must have some idea about the job market. The campus interviews and recruitments are carried out by some large firms. Small firms arrange interviews at their company premises to recruit entry level electrical engineering jobs.

There are some common interests shared by small and large organisations while recruiting for entry level electrical engineering jobs. The first thing is the basic knowledge a fresher possess on electrical engineering. The second thing is the IQ level of the candidate. Further a firm will look for physical capabilities, personality etc of the candidate while looking for recruits for entry level electrical engineering jobs.

A student who appear for or apply for entry level electrical engineering jobs must prepare a good bio-data (resume) that contain all their positive points. This resume must be prepared with the help of your teachers and parents. To get help from elders is important because they know how your resume appear before an employer who recruit for entry level electrical engineering jobs. It is also very important to add the specific projects you have done, industrial training you have undergone and part-time jobs you have attended. Also make sure to modify the resume at frequent intervals to add the expertise you have gained. I personally recommend for different resumes for different organisations. Please remember that the resume is the most probable starting point for an interview that select an entry level electrical engineering job.

Friday, April 13, 2012

Electric Shock On Train Live

A man grabs the high voltage wires above a train and electrocutes himself, he then bursts into flames.

Symmetrical components - Positive, Negative and Zero Sequence Components

Wikipedia says that In electrical engineering, the method of symmetrical components is used to simplify analysis of unbalanced three phase power systems under both normal and abnormal conditions.

There are three sets of independent components in a three-phase system: positive, negative and zero for both current and voltage. Positive sequence voltages are supplied by generators within the system and are always present. A second set of balanced phasors are also equal in magnitude and displaced 120 degrees apart, but display a counter-clockwise rotation sequence of A-C-B, which represents a negative sequence. The final set of balanced phasors is equal in magnitude and in phase with each other, however since there is no rotation sequence this is known as a zero sequence.

Under a no fault condition, the power system is considered to be essentially a symmetrical system and therefore only positive sequence currents and voltages exist. At the time of a fault, positive, negative and possibly zero sequence currents and voltages exist. Using real world phase voltages and currents along with Fortescue’s formulas, all positive, negative and zero sequence currents can be calculated. Protective relays use these sequence components along with phase current and/or voltage data as the input to protective elements.

Tuesday, April 10, 2012

What is a dedicated line?

This is an extract from a white paper circulated by APC!

A dedicated line is a power line, which runs from the circuit breaker panel to the critical load and has no other loads connected to it. Normally a circuit breaker feeds multiple receptacles; with a dedicated line, a single circuit breaker feeds only the one receptacle that the protected load is connected to. The advantages of a dedicated line are threefold:

First, the protected load is not subjected to input voltage variations that could be caused by other loads sharing the same circuit. Such variations could result from the voltage drops in the building wiring, which are caused by the currents drawn by the adjacent loads. These variations are prevented by the dedicated line since the adjacent loads no longer share the same building wiring. Second, the protected load is not subjected to variations in the voltage of the grounding wire, which might result from ground noise injection from adjacent loads. This reduces intersystem ground noise.

Third, the protected load is not subject to the potential hazard of having its source circuit breaker tripped by the malfunction of another load, since with a dedicated line no other load shares the same circuit breaker.

A dedicated line may be installed at any time. An electrician simply installs a new circuit breaker in the circuit breaker panel and runs a new wire to either a new or existing AC receptacle.

Monday, April 9, 2012

BEE (Bureau of Energy Efficiency)

Energy Efficiency may be the most discussed words while shopping for electrical appliances. But since the terms are purely technical and there are several variations like capacity, speed and efficiency common man stand puzzled before the shop keeper. So some indications are required to easily identify the power efficiency of an electrical appliance. Here comes a BEE (Bureau of Energy Efficiency) label star rating. The BEE Star Energy Efficiency Labels have been created to standardize the energy efficiency ratings of different electrical appliances and indicate energy consumption under standard test conditions. BEE (Bureau of Energy Efficiency) label indicates the efficiency of the equipment with 1-5 stars. The more star the label bears the more efficient it will be. For example a 5 star rated AC or refrigerator is more energy efficient that an appliance bearing 4 stars. So go for maximum stars while you purchase an electrical appliance. The more stars means more energy efficiency and the more money it will save over the life. Energy saving is for your pocket and for the self reliance of our country.

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