Electrical Heights

Classification of Instrumentation System Instrumentation system Null and Deflection type Instruments: Deflection type instruments: The instruments in which deflection of the instrument forms the basis of measuremenl are called as deflection type instruments. The example of deflection type instruments is the permanent magnet moving coil (PMMC) ammeter. PMMC AMMETER The deflection of the coil is proportional to the current that is to be measured. Torque Td, that acts on the moving coil is proportional to current.The opposing effect is produced by a spring, having torque Tc which is proportional to the deflection. When the spring is balanced Tc=Td. The value of the current depends on the deflection.Thus,the value of the measured quantity depends upon the calibration of the instrument. Null type Instruments The instrument in which, a null or zero indication will lead to the determination of the magnitude of the measured quantity such instruments are c

Active and Passive Instruments: Active and passive Instruments Passive Instruments: The instruments where the output is produced completely by the quantity that is measured are called passive instruments. The example of passive instrument is a pressure gauge.Fig  shows a pressure gauge. Passive  Instrument As the pressure in the liquid changes, the piston moves.The pointer is connected to the piston. No other source of energy is used. The liquid pressure is the only source. Thus,the piston and pointer movement while measurement is entirely dependent on the liquid pressure. Active Instruments: Active instruments are the instruments in which the quantity to be measured activates the magnitude of external power input source that produces the measurement. The liquid level indicator is an example of an active instrument.Fig.1.4.2 shows a liquid level indicator. Active Instruments The power source is required in order to se

Functional elements of an Instrumentation System: Instrumentation system Any instrumentation system can be described with the help of a block diagram.The block diagram of an instrumentation system describes the essential elements and their functions in a measuring system. Fig. shows the block diagram showing the functional elements of an instrumentation system.                     Instrument system The elements can be grouped as: Primary sensing element. Data conditioning element. Data presentation element. Each element comprises of a number of distinct components that perform a particular function in the measurement procedure.The function of each element is important.  Primary Sensing Element: To the primary sensing element the quantity to be measured is applied.e.g.in an ammeter, coil carrying current to be measured is a primary sensing element. Generally a transducer follows a primary sensing element.The transducer converts the measured to corresp

  Definition of Measurement and Calibration Measurement and Calibration Measurement: Measurement of a given quantity is the act or result of a quantitative comparison between an unknown quantity and a predefined standard quantity e.g.for measuring the weight of a quantity, the standard taken is 1 kg. Measurement  using an instrument as a physical means of determining a quantity or variable. Instrument: Define an instrument: Instrument can be defined as a device for measuring the value or magnitude of a quantity or variable. The electronic instrument is based on electrical or electronic principles for their measurement. Calibration: What do you mean by calibration?  Calibration is a process of estimating the value of a quantity by comparing that quantity with given standard quantity. The standard with which comparison is made is called as standard instrument. The unknown quantity is to be calibrated.This quantity is called as test quantity. If an

CLASSIFICATION OF NETWORKS Classification of Network The electrical networks may be classified in a number of ways depending upon following. (i)the kind of elements of which the network is composed of and on the basis of their properties (ii)in terms of the general properties of its responses to excitation applied to its input terminals.Thus,we have linear and non linear networks, time invariant and time variant networks, active and passive networks etc.   Linearity: In a linear network, the voltage-current relationship is show by a linear equation. Suppose the network to be classified is under relaxed condition such that the initial condition is zero and an excitation e1(t)is applied for which the response is c1(t)and for excitation e2(t), the response is c2(t).Then the network is classified as linear if for excitation e1(t)+e2(t), the response is c1(t)+c2(t).This shows that a linearity follows superposition principle. Hence,from physical point of view, it may be

 TYPES OF ELECTRIC ENERGY:     Electrical Energy in the methods of science,we immediately become suspicious of any scheme who claims to create energy. The law of conservation of energy is  that energy can neither be created nor destroyed. However, its form can be converted such that energy can be converted from one form of energy to another. Electric energy is the energy who converted from some other form. There are a numbers of way in which this is accomplished. Some of them are as follows: (1)Electrochemical energy conversion: Electric batteries produce electric energy with  the help of  conversion of chemical energy. A potentially important use of this type of batteries is in the electric car. Fuel cell is in this general classification. (2)Electromechanical energy conversion: The rotating generator produces electric energy from mechanical energy of rotation. Usually, the mechanical energy who converted from thermal energy by a turbine and, in turn

 CHARGE AND CURRENT: CURRENT concept of charge is based on atomic theory. We know that all matter is made up of fundamental building blocks called atoms and that the atoms,in turn,are composed of different kinds of fundamental particles. The three most important particles are the electron,the proton,and the neutron. The electron possesses negative charge,the proton possesses equal-magnitude positive charge and the neutron have neutral or has no charge at all. As we rub the rubber comb with woolen cloth,the comb acquires its negative charge because some of the electrons on the wool are rubbed off on to the comb;the cloth then has an insufficient number of electrons to maintain its electrical neutrality and thus behaves as a positive charge. When electrons are removed from the substance,that substance becomes a positively charged and the substance acquiring electrons from the other substance becomes a negatively charged. The basic unit of the charge,called the Coul

Difference Between Slip ring and Squirrel cage induction motor Difference Between Squirrel cage and Slip ring inductio motor Slip ring or phase wound Induction motor 1.Construction is complicated due to presence of slip ring and brushes. 2.The rotor winding is similar to the stator winding. 3.We can easily add rotor resistance by using slip ring and brushes. 4.Due to presence of external resistance high starting torque can be obtained. 5.Slip ring and brushes are present. 6.Frequent maintenance is required due to presence of brushes. 7.The construction is complicated and the presence of brushes and slip ring makes the motor more costly. 8.This motor is rarely used,only 10% industry uses slip ring induction motor. 9.Rotor copper loss is high and so less efficiency. 10.Speed control by rotor resistance method is possible. 11.Slip ring induction motor.is used where high starting torque is required i.e.   in hoists, cranes, eleva