World Of Electrical

Advantages and Disadvantages of Electromagnetic Relay There are many Advantages, Disadvantages and Application of Electromagnetic Relay which will be mentioned in this article Advantages and Disadvantages of Electromagnetic Relay Advantages Of Electromagnetic Relay ✓ Electromagnetic relays have fast operation and fast reset. ✓ They can be used for both a.c.and d.c.systems for protection of a.c.and d.c. equipments. ✓ Electromagnetic relays operating speeds which has the ability to operate in milliseconds are also can be possible. ✓ They have the properties such as simple, robust, compact and most reliable. ✓ These relays are almost instantaneous. Though instantaneous the operating time of the relay varies with the current. With extra arrangements like dashpot, copper rings etc. ✓ slow operating times and reset can be possible. Disadvantages Of Electromagnetic Relay ✓ High burden level instrument transformers are re

Over Current Protection Of Transformer Over Current Protection Of Transformer Now we learn over current protection using circuit Diagram which is shown in below figure. Circuit Diagram of Over Current Protection Of Transformer Transformer is connected in star-delta.CTs are connected in the primary lines. Over current Relay-1 and 2 is connected in two phases. Relay-3 is connected across the star point of the over current relay and the earth. Over current Relay-1 and 2 operates when there is phase to phase fault or when there is over load. Relay-3 operates in case of the earth fault. Similar protection can be given in the secondary winding also. This type of protection is used for primary protection of small transformers and back-up protection of large transformers. The primary winding of transformer is connected in star and the CTs on that side are connected in delta. The secondary winding of transformer i

Percentage Differential Relay and Protection for Power Transformer The differential protection scheme is used for the protection of transformers having rating 5 MVA and above against internal phase to phase and phase to earth faults. Percentage Differential Relay and Protection for Power Transformer The basic principle of operation of differential relay is that the vector difference of two or more similar electrical quantities current or voltage goes beyond the specified or the set value then the relay will operate otherwise the relay will not operate. The connection diagram of this type of protection is shown in below figure: Circuit Diagram of Percentage Differential Relay and Protection for Power Transformer The primary winding of transformer is connected in star and the CTs on that side are connected in delta. The secondary winding of transformer is connected in delta and the CTs on that side are connected in star. This pr

Transformer Faults Transformer Faults There are many faults can occur in power transformer which is mentioned below: 1.Over heating of the core 2.Improper contacts on the tap changer 3.Failure of the cooling system 4.Phase to phase fault 5.Earth fault 6.Inter turn fault 7.Over load 8.Over voltage The effect of all Faults is described below: 1. Over heating of the core Transformer core gets over heated due to excessive loading, failure of the cooling system or fault in the core. e.g. shorting of lamination. Over heating of the core Due to this, the life of the insulation is reduced and so the life of transformer is reduced. 2. Improper contacts on the tap changer Arcing occurs and the insulation is damaged when the contacts of the tap changer are not proper. 3. Failure of the cooling system Cooling is affected when cooling fan stops working or there is fault in the circulating system. Due to this t

Advantages and Disadvantages of Interconnected Power System Advantages of Interconnected Power System Interconnected power systems have many advantages which is Described below: ✓ An important advantage of interconnected system is that the peak load of the power station can be exchanged. Advantages and Disadvantages of Interconnected Power System ✓ If the load curve of a power station shows a peak demand that is greater than the rated capacity of the plant, then the excess load can be shared by other stations interconnected with it. √ The interconnected system makes it possible to use the older and less efficient plants to carry peak loads of short durations. √ Although such plants may be inadequate when used alone, yet they have sufficient capacity to carry short peaks of loads when interconnected with other modern plants. √ Therefore, interconnected system gives a direct key to the use of obsolete plants. ∆ The interconnected syste

Basics concept of Interconnected Power System The main requirement of any power system is to give an uninterrupted power supply. Basic Concept of Interconnected Power System In some parts of the country there are resources of generating power but their  requirements is low where as in other parts power requirement is large as compared to available resource of power. These above difficulties can be reduced by interconnecting different power stations in parallel. The connection of numbers of power generating stations in parallel is known as Interconnected  Power System. Inter connected power system is basically an interconnection of the buses of more than one generating station. So as to utilize the unused generated power capacity of connected generators during peak demand. It is also be simply defined as 'A distribution system with multiple available power sources that can loop throughout the network.'  If one

What is Instrumentation? And Modes of Measurement Definition of Instrumentation The technology of using instruments to measure and control the physical and chemical properties of materials is called “ instrumentation ". What is Instrumentation? And Modes of Measurement When the instruments are used for the measurement and control of industrial manufacturing , conversion or treatment processes, the term process instrumentation is applied. When the measuring and controlling instruments are combined so that measurements provide impulses for remote automatic action, the result is called a control system. Modes of Measurement There are the three modes of measurement: 1. Primary Measurement 2. Secondary Measurement 3. Tertiary Measurement All the three modes are described below: (1) Primary Measurements In the primary measurement sought value of a parameter is determined by comparing it directly with reference standar

Why we use Circuit Breakers?  Circuit breakers are mechanical device designed to close or open contact members. Thus closing or opening an electrical circuit under normal or abnormal conditions. A circuit breaker has fixed and moving contacts.These contacts remain in contact whenever the circuit breaker is in normal operation. Why we use Circuit breakers? Whenever fault occurs the contacts separate out resulting in arc between the electrodes. The production of arc not only delays the current interruption process but it also generates enormous heat which may cause damage to the syatem or the breaker itself. Thus the main problem is to extinguish the arc whenever it occurs is circuit breaker . The temperature of arc may be as high as 6000C°. Methods of arc creation Commonly used methods of arc creation are mentioned below: (1) High resistance interruption By increasing the effectiv

Variable Inductance Transducer | Classification Of Variable Inductance Transducer Variable Inductance Transducer | Classification Of Variable Inductance Transducer These are based on a change in the magnetic characteristic of an electrical circuit in response to a measurand which may be displacement, velocity, acceleration etc. Variable inductive transducer may be classified as follows: 1.Self-generating type In this type voltage is generated because of the relative motion between a conductor and a magnetic field. These may be further classified as follows: (A)Electromagnetic type (B)Electrodynamic type (C)Eddy current type 2.Passive type In this type the motion of an object results in change in the inductance of the coils of the transducer. These may be further classified as follows: (A)Variable reluctance (B)Mutual inductance (C)Differential transfer type 1.Self-generating Type (A)Eleotromagnetic t

Cathode Ray Oscilloscope ( C. R. O. ) | Working and Application of C. R. O Cathode Ray Oscilloscope ( C. R. O. ) | Working and Application of C. R. O Definition and Basic Details of C. R. O. A cathode-ray oscilloscope is an instrument which presents signal wave-forms visually. It is also useful for comparing two signals in phase,frequency or amplitude. A  C.R.O.can operate upto 50 MHz, can allow viewing of signals within a time span of a few nanoseconds and can provide a number of waveform displays simultaneously on the screen. It also has the ability to hold the displays for a short or long time (of many hours)so that original signal may be compared with one coming on later. A block diagram of cathode-ray oscilloscope is shown in below figure Block Diagram of cathode Ray Oscilloscope Cathode Ray Tube(C.R.T.) A cathode ray tube is the 'heart of an oscilloscope and is very similar to the pic