Electrical Engineering

A Direct-On-Line (DOL) starter is an electronic 3-phase motor-control system which offers soft starts in DELTA configuration. DOL starters are now replacing the use of manual or semi-automatic "star-delta" starters.

In this way of starting a 3-phase motor, full line voltages are applied to the motor through relays and contactors. The DOL is nowadays the most common type of 3-phase motor starter used.

It has a "closing circuit" and an "opening circuit". The closing circuit is for applying the service lines to the motor and the opening - or "tripping" - circuit protects the motor by cutting-off (or "tripping") power to the motor from the service lines if there is any overload condition, a single phasing fault, etc.

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They step down the voltage from the main power generating stations at different intervals so that for a domestic power service it is delivered at 240V.

Additional answer

When you pass electricity through wires you warm the wires up. This heat is a total loss of energy. So you want to keep the loss to a minimum. The heating effect of electricity is increased with an increase in amperage (the current). The amount of power that goes through the wires is a function of the voltage x amps. So to transmit a certain amount of power with the minimum heat loss you keep the current down which mean pushing the voltage up. This is why the transmission wires near the generating station carry very high volatges. But these voltages are unsafe for use in domestic circuits so they have to be reduced by a series of transformers from the high voltages in the main lines to lower voltages at substations to even lower voltages in the home.

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just apply the formula :-

p=v*i*cos(angle);

now you have the power rating,load so in turn power factor so you can easily calculate the value of current.

with the help of current you can chose the cable available in the market either the aluminum or copper wire

satendra.svnit@gmail.com

Homes are single phase. You can have 220VAC in a home, although not all homes have 220VAC. In the United States and Canada, the 240VAC is "center-tapped_ to provide 2 120 Volt halves. It doesn't matter which half is used on a 120 volt line, just so long as the house is APPROXIMATELY balanced between the two halves.

In some countries, it is normal for residences to be supplied with three-phase. In European countries, the lines (not 'phases') are identifed by the colour of the insulation -brown, black, and grey. The neutral is blue.

Most police and detectives learn much of what they need to know on the job, often in their agency's police academy. Civil service regulations govern the appointment of police and detectives in most States, large municipalities, and special police agencies, as well as in many smaller jurisdictions. Candidates must be U.S. citizens, usually at least 20 years old, and must meet rigorous physical and personal qualifications.

Education and training. Applicants usually must have at least a high school education, and some departments require 1 or 2 years of college coursework or, in some cases, a college degree.

Law enforcement agencies encourage applicants to take courses or training related to law enforcement subjects after high school. Many entry-level applicants for police jobs have completed some formal postsecondary education, and a significant number are college graduates. Many junior colleges, colleges, and universities offer programs in law enforcement or administration of justice.

Physical education classes and participating in sports are also helpful in developing the competitiveness, stamina, and agility needed for many law enforcement positions. Knowledge of a foreign language is an asset in many Federal agencies and urban departments.

Many agencies pay all or part of the tuition for officers to work toward degrees in criminal justice, police science, administration of justice, or public administration and pay higher salaries to those who earn such a degree.

Before their first assignments, officers usually go through a period of training. In State and large local police departments, recruits get training in their agency's police academy, often for 12 to 14 weeks. In small agencies, recruits often attend a regional or State academy. Training includes classroom instruction in constitutional law and civil rights, State laws and local ordinances, and accident investigation. Recruits also receive training and supervised experience in patrol, traffic control, the use of firearms, self-defense, first aid, and emergency response. Police departments in some large cities hire high school graduates who are still in their teens as police cadets or trainees. They do clerical work and attend classes, usually for 1 to 2 years, until they reach the minimum age requirement and can be appointed to the regular force.

To be considered for appointment as an FBI agent, an applicant must be a college graduate and have at least 3 years of professional work experience, or have an advanced degree plus 2 years of professional work experience. An applicant who meets these criteria must also have one of the following: a college major in accounting, electrical engineering, information technology, or computer science; fluency in a foreign language; a degree from an accredited law school; or 3 years of related full-time work experience. All new FBI agents undergo 18 weeks of training at the FBI Academy on the U.S. Marine Corps base in Quantico, Virginia.

Most other Federal law enforcement agencies require either a bachelor's degree or related work experience or a combination of the two. Federal law enforcement agents undergo extensive training, usually at the U.S. Marine Corps base in Quantico, Virginia, or the Federal Law Enforcement Training Center in Glynco, Georgia. The educational requirements, qualifications, and training information for a particular Federal agency can be found on the agency's Web site, most of which are listed in the last section of this statement.

Fish and game wardens also must meet specific requirements. Most States require at least 2 years of college study. Once hired, fish and game wardens attend a training academy lasting from 3 to 12 months, sometimes followed by further training in the field.

Other qualifications. Civil service regulations govern the appointment of police and detectives in most States, large municipalities, and special police agencies, as well as in many smaller jurisdictions. Candidates must be U.S. citizens, usually at least 20 years old, and must meet rigorous physical and personal qualifications. Physical examinations for entrance into law enforcement often include tests of vision, hearing, strength, and agility. Eligibility for appointment usually depends on performance in competitive written examinations and previous education and experience.

Candidates should enjoy working with people and meeting the public. Because personal characteristics such as honesty, sound judgment, integrity, and a sense of responsibility are especially important in law enforcement, candidates are interviewed by senior officers, and their character traits and backgrounds are investigated. In some agencies, candidates are interviewed by a psychiatrist or a psychologist or given a personality test. Most applicants are subjected to lie detector examinations or drug testing. Some agencies subject sworn personnel to random drug testing as a condition of continuing employment.

Advancement. Police officers usually become eligible for promotion after a probationary period ranging from 6 months to 3 years. In large departments, promotion may enable an officer to become a detective or to specialize in one type of police work, such as working with juveniles. Promotions to corporal, sergeant, lieutenant, and captain usually are made according to a candidate's position on a promotion list, as determined by scores on a written examination and on-the-job performance.

Continuing training helps police officers, detectives, and special agents improve their job performance. Through police department academies, regional centers for public safety employees established by the States, and Federal agency training centers, instructors provide annual training in self-defense tactics, firearms, use-of-force policies, sensitivity and communications skills, crowd-control techniques, relevant legal developments, and advances in law enforcement equipment.

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Various energy losses occur in transformers:

Copper losses, the resistance to the current flow in the windings which heats the conductors.

Iron losses, which are of two kinds:

• eddy current losses which flow in the laminations of the core caused by the magnetization and re-magnetisation of the core, which also causes heatingof the core. Eddy current losses can be greatly reduced by not making the out of a solid piece of iron.

  That is why transformer cores are generally made of lots of separate thin "laminations" which are insulated from one another by being bonded together using an epoxy resin adhesive.

• hysteresis losses which are again caused by the magnetizing and de-magnetising of the core.

  These are reduced by making the laminations of silicon steels, which have lower hysteresis losses than plain iron.

Together all these losses lead to a total efficiency of about 97 to 98%, which will alter depending upon the load current that the transformer is supplying.

The best answer I can find is 60 volts. I'm not sure if this is AC or DC. However, it's not just the voltage that kills. You can be electrocuted by a car battery if you make a good connection to both poles. Most car batteries have around a 600 amp output. Even at 12 volts, this can be deadly. Keep in mind also that it's easier to be killed by DC than by AC. ---- IF YOU'RE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS. If you do this work yourself, always turn off the power at the breaker box/fuse panel BEFORE you attempt to do any work AND always use a meter or voltage indicator to insure the circuit is, in fact, de-energized.