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Possibly there may be a rapid reduction in the resistance of an electrical insulator (windings) causing uneven field stress.This is completely correctable and you should consult a expert in the field of Transformers.
A variable speed drive can be achieved by variable-frequency control
The emf induced in the stator of the induction motor is given by:
E1=4.44kw1føT1
If supply is changed E1 will also change to maintain the same air gap flux.If the stator voltage drop is neglected the terminal voltage is equal to E1.But in order to avoid saturation and to minimize losses,motor is operated at rated air gap flux by varying frequency in such a way such that V/f ratio remains constant.
The variable frequency is obtained using a)Voiltage source inverter b)current source inverter c)cycloconverter
soft starter generally make use of thyristor with a varying firing angle
The word “electronics” stands for electronmechanics.It is the field of engineering that deals with the motion of electrons under the influence of applied electric field &/or magnetic field.
Its completely right to say “Electronics is a subset of Electrical”.
This can be viewed from other term too. As we know the average power consumed by a inductor or a capacitor over a complete cycle is zero.During the first half cycle a field builds up across the inductor and during the second half cycle the field collapses. So power has to be returned back to source
Eddy currents are the currents induced in the body of a conductor when the amount of magnetic flux linked with the conductor changes.
For example when we move a metal plate out of a magnetic field,the relative motion of the field and the conductor again induces a current in the conductor.The conduction electrons making up the induced current whirl about within the plate as if they were caught in an eddy(or whirlpool) of water. This is known as eddy current.
Its magnitude is given by: i=(induced emf/resistance)
In delta zig-zag connection the primary is connected in delta.Each secondary winding is made in two halves such as a1-a2,b1-b2,c1-c2 and the six halves are then connected to form a zig zag connection.A1,a1,a2 are of same polarity and similarly for other phases.If the voltage of each half of the transformer secondary is V1/2,the pjase voltage of the secondary system is (sqrt(3)/2)*V2 and the line voltage is 3/2*V2. Thus in delta zig zag connection the line voltage transformation ration is 1.5 times the phase turn-ratio is 3/2 times line transformation ratio.
A zig-zag transformer is a special form of autotransformer used to provide grounding (earthing) on three-phase systems that otherwise have no connection to ground . It has primary windings but no secondary winding.They provides a path for current that is common to all three phases.Another application includes control of harmonic currents
The forum is meant for electrical engineering discussion and not any PC password related tips.This is way off base.
A protective earth (PE) connection ensures that all exposed conductive surfaces are at the same electrical potential as the surface of the Earth, to avoid the risk of electrical shock if a person touches a device in which an insulation fault has occurred. It ensures that in the case of an insulation fault (a “short circuit”), a very high current flows, which will trigger an overcurrent protection device (fuse, circuit breaker) that disconnects the power supply.
Ground and neutral are closely related. Under certain conditions, a conductor used to connect to a system neutral is also used for grounding (earthing) of equipment and structures. Current carried on a grounding conductor can result in objectionable or dangerous voltages appearing on equipment enclosures, so a neutral conductor is used also to connect equipment enclosures to earth, care must be taken that the neutral conductor never rises to a high voltage with respect to local ground. Normally a grounding conductor does not carry current.
senthilkumar said:
sir,I am incomplete study in diplamo electrical & electronics before 15 years.I have more intresting and experiance in wireing work. How can I get the licence from the electrical board of india? can I have any electrical exam.please guide me .Thank you very much.
You have to get a licence from the respective state. This site may be helpful for you Issue of Certificate of Competency Class-I And Class-II
