electrialstandards

In recent days JIO has generated lot of buzz which offers free calling for lifetime and free internet up to December. There is also new technology associated with JIO is VoLTE. Mobile phone manufacturers are selling phones with VoLTE enabled technology. Now there is curiosity what is VoLTE? and how it is different? In this below article we will learn what is VoLTE technology all about?:- VoLTE:- There is new technology in field of data services. VoLTE is known as Voice over Long-Term Evolution. It is used for providing a uniform format of voice traffic on LTE and other systems including CSFB (Circuit Switched Fall Back) and SV-LTE(Simultaneous Voice Long term evolution). This technology is used for better voice call quality. VoLTE uses 4G technology and it is based on packet switching on the other hand 2G and 3G networks uses circuit based switch. Now when we make a call using 2G and 3G then there is bandwidth assigned to that call this will not allow to  terminate   until ...

There are so many methods available by which harmonics can be reduced in system and power quality can be improved. There are following methods of reducing the harmonics in system:- (i)                   DC choke (ii)                 By reducing harmonics at loads (iii)                By using filters Now let’s discuss about them:- (i)                  DC choke:- VFD’s are main source of harmonics generation in a plant. DC choke is used in VFD’s to reduce harmonics. DC choking is an inductance in series with semiconductor bridge circuit. DC choke provides reduction in 5th and 7th Harmonics. DC choke is comparable to an equivalent AC-side line reactor, although the %Total Harmonic Di...

Harmonics in electrical systems:- Before discussing about consequences of Harmonics you must know what are harmonics:- Harmonics are electric current and voltages that causes power quality problems. These are generated due to electronic equipment’s which draws non linear loads with abrupt pulses. These pulses causes distorted current and voltages causes of which will be discussed in this article. Harmonics are classified according of level of harmonics these are multiple of frequencies such as 2 nd level, 3 rd level, 4 th level, and upto 11 th levels Where 2 nd level means Harmonics with frequency of 100 HZ 3 rd level means Harmonics with frequency level of 150 HZ And similar for other levels Now 2 nd level, 5 th level, 8 th level, and 11 th level will have –ve sequence of currents 3 rd level, 6 th level and 9 th level will have zero sequence of currents 4 th level, 7 th level, 10 th levels will have +ve sequence of currents Harmonics are now integral part of electricity. ...

Electricity works on an idea that whenever two dissimilar metals bring in contact with an electrolytic solution then there will electron movement in these metals when these metals are connected using a conductor. All plants consist of fluid which is electrolyte for metals. So using above principle of inserting metals in a fluid will leads to electricity generation. We have done during childhood for generating electricity from potatoes. It works on principle that Potatoes contains a liquid in which many water soluble chemicals are present. So these may cause a chemical reaction with one or both of our electrodes. So we will get some electricity from that . Best result will be obtained while using zinc and copper electrodes. Let’s discuss about the same experiment:- For conducting experiment let’s take 8 potatoes. We will take 8 potatoes to get enough electricity to light up a LED. Now insert different metals of any shapes into these potatoes. Now by using small wires all potatoes are ...

Synchronous machines construction depends upon type of prime mover used in machines. There are following types of prime movers used in power generation:- 1.        Steam turbines 2.        Hydraulic Turbines 3.        Diesel Engines Let’s discuss them :- 1.      Steam turbine:- These types of synchronous machines have high speed.  Generators driven by steam turbine are also called Turbogenerators. Maximum speed of Turbogenerators is 3000 RPM as per formula Frequency= PN/ 120; Where P is no. of poles N is no. of revolutions In 2 Pole machine at 50 HZ frequency Speed of Turbogenerator comes out to be= 50X120/ 2= 3000 RPM With Such high speed lower value of armature diameter is to be designed. Lower diameter is selected to limit the centrifugal forces which have very much influence on the generator design. Peripheral Speed of a Machine is given by formula as below:- Periphera...

In case of synchronous machines  Armature is always placed on stator and field winding on armature as there are following advantages:- 1.      Better economy:- It is always economical to place armature winding on Stator and field winding on rotor in synchronous machines as this can be illustrated by example as below:- Consider a 3-Phase Star connected 500 MVA, 11KV synchronous machine, now its line current will be = 500X10 3                                11 X Which Will be = 26244 A Now If we place armature winding on rotor than we will required 3 slip rings each will be capable of handling such a high current of 26244A. Further Slip rings needed to be insulated from shaft for a voltage= 11/  = 6.35 KV. Also Star point needed to be brought out by using fourth slip ring which will be grounded through a resista...

In electrical systems its usual that cable may get faulty there are following methods of checking the type of fault in cable:- 1.      Using Meggar for LT Cables:- Meggar is most commonly used method for checking the fault in cables. If Meggar is used at 500V/ 1000V DC then cable shows infinite value If cable is Ok.  if value lies above 100 Mohm then cable is also acceptable it indicates only that there cable is having some moisture which will be dried out when cable is put on load but if value falls below this value upto 50 Mohm then it will be used where there were light loads. If there is value is near to zero than cable should not be used as if cable insulation level between two leads is zero this means cable is short circuited. If Cable insulation with respect their leads is ok but between lead and earth is zero than this indicates cable get short circuited with armored. In Meggar we can check resistance value also in this 2 leads one is placed on resi...