Measuring Instruments: Classification, Absolute and secondary instruments, indicating instruments, control, balancing and damping, constructional details, characteristics, errors in measurement, Ammeters, ... Give examples. For example Rayleigh’s current balance and Tangent galvanometer are absolute instruments. As calibration of weights is much easier than careful choice The null condition depends on other known conditions. The liquid pressure is the only source. •An alternative type of pressure gauge is the deadweight gauge shown in Figure 2.3, which is … perfectly acceptable in this case because of the infrequent nature of Data conditioning element. If necessary, the sensitivity of a null indicator can be improved by means of photoelectric, electronic, and other types of amplifiers. The rev counter sketched in Figure 2.4 is an example of a digital instrument. An alternative type of pressure gauge is the deadweight gauge shown in Figure below, which is a null-type instrument. Ampere hour meters, watt-hour meters, energy meters are the few examples of these instruments. There are two main types of the measuring instruments: analogue and digital. spring, whilst for the second it relies on the calibration of the 2. All materials are broadly classified into three categories depending upon the resistance they offer to the flow of current through them. The pressure gauge just mentioned is a good example of a deflection type of instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. the first one it depends on the linearity and calibration of the C# (CSharp) MetadataType - 30 examples found. https://courses.lumenlearning.com/physics/chapter/21-5-null-measurements Calibration: What do you mean by calibration? convenient. Definition: The instrument type in which output entirely depends on quantity to be measured. Instrument system The elements can be grouped as: Primary sensing element. For example, differential pressure on a pitot tube is used to determine airspeed. The unknown quantity is to be calibrated.This quantity is called as test quantity. 2.1.2 Null-type and deflection-type instruments • The pressure gauge just mentioned is a good example of a deflection type of instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. Instruments are subdivided into active and passive based on whether the output of instrument is produced by the quantity being measured simply changes the magnitude of some external power source. Data presentation element. In these null type instruments, a zero or null Indication leads to determination of the magnitude of measured quantity.In contrast to deflection type instruments, a null type instrument attempts to maintain the deflection at zero by suitable application of an effect opposing that … This is (a) A voltage source connected to a long wire resistor passes a constant current I through it. future and option are used to define the contract specs of a series of instruments. SSC JE Electrical Important MCQ PDF Part 21 1.In Figure if i = cos 4t and v = sin 4t, the element is A. a resistor B. a capacitor C. an inductor D. none of these Answer : B (Given i = cos 4t and v = sin 4t We know cos x=sin (x+90⁰) cos (4t)=sin (4t+90⁰) So i = sin (4t+90⁰)—-(1) v = sin 4t—-(2) By equation (1) & (2) it clear voltage lags the current by 90o. shows the D.C.potentiometer. The sensitivity of the instruments is less than the null type instruments. Disadvantages of Deflection Type Instrument. 2.1.2 Null-type and deflection-type instruments The pressure gauge just mentioned is a good example of a deflection type of instrument, Example: PMMC instrument. No other source of energy is used. The liquid level indicator is an example of an active instrument.Fig.1.4.2 shows a liquid level indicator. shows the block diagram showing the functional elements of an instrumentation system. 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. Active instruments B. 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 called null type instruments. The measured quantity produced somephysical effects that engenders a similar but opposingeffect in some part of the instrument. The value of the measured quantity depends on the calibration of the instruments. The circuit shown in Figure 7.1 is used, in which the known fixed resistance values are given by R 2 = 98.3 Ω and R 3 = 102.2 Ω. (a) With a neat diagram explain in detail the construction of PMMC instrument. measured is displayed in terms of the amount of movement of a pointer. against a scale than to add and subtract weights until a null point is The pressure gauge is a good example of the null-type instrument is preferable because of its superior until the downward force balances the fluid pressure. shows the D.C.potentiometer. accuracy. Advantages and disadvantages of null and deflection type instruments with use of null type instruments ( ) Studies, courses, subjects, and textbooks for your search: a sensitive instrument for detecting the inequality of physical quantities being compared in the null method. and calibration of a linear-characteristic spring, this means that the Here, weights are put on top of the piston Ammeters, Voltmeters and wattmeters are the examples of these instruments. •The pressure gauge just mentioned is a good example of a deflection type of instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. An alternative type of pressure gauge is the dead-weight gauge which 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. A prime example of this type of system is the PMMC (Permanent Magnet Moving Coil) Instruments. Electrical & Electronics Measurement & Instrumentation Test Questions Set 1 with answers and explanation for placement tests, other tests etc. A dc potentiometer is a null- type instrument. The null condition depends on other known conditions. An alternative type of pressure gauge is the dead-weight gauge which is a null-type instrument. 2) Secondary instruments :: These instruments are so constructed that the quantity being measured … Q. 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. A null-type Wheatstone bridge is used to accurately measure the resistance of a platinum resistance thermometer during a calibration procedure. About the null or deflection type of instruments The pressure gauge is a good example of a deflection-type instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. A digital instrument has an output that varies in discrete steps and so can only have a finite number of values. Passive  Instrument As the pressure in the liquid changes, the piston moves.The pointer is connected to the piston. 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. The energy expanded in moving the pointer is derived entirely from the change in pressure measured. needed to reach this null position. (j) What is piezoelectric effect. 2.1.2 Null-type and deflection-type instruments • The pressure gauge just mentioned is a good example of a deflection type of instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. The accuracy of these two instruments depends on different things. Active And Passive Instruments THANK YOU Advantages And Disadvantages of Null - Type Start Advantages And Disadvantages of Deflection Type Deflection-type 1) They are very much accurate. An alternative type of pressure gauge is … They maintain the position of the pointer stationary by producing opposing effect. Weights are These are more accurate and highly sensitive as compared to deflection-type instruments. An alternative type of pressure gauge is the dead-weight gauge which is a null-type instrument. An example of an active instrument is a float-type petrol tank level indicator as sketched in Figure below. i.e. Thus for the operation of null type instruments following steps are required: The DC potentiometer is an example of null type potentiometer. Well, Type: Null sports a few design elements that call back to the motif of a Null-Type instrument. Instrument Types and Performance Characteristics Digital Instruments. • An alternative type of pressure gauge is the deadweight gauge shown in Figure 2.3, which is a null-type instrument. The pressure gauge is a good example of a deflection-type instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. A cam is attached to the revolving body whose motion is being measured, and on each revolution the cam opens and closes a switch. in accordance with the general rule that null-type instruments are You can rate examples to help us improve the quality of examples. Null/Deflection Null type instruments: In which a zero or null indication leads to the determination of magnitude of the quantity being measured. The rev counter sketched in Figure 2.4 is an example of a digital instrument. Here, the change in petrol level moves a potentiometer arm, and the output signal consists of a proportion of the external voltage source applied across the two ends of the potentiometer. For Example: DC potentiometer Deflection type instrument: In which the quantity being measured produces some effect due to which pointer deflects. Thus,the piston and pointer movement while measurement is entirely dependent on the liquid pressure. The standard with which comparison is made is called as standard instrument. .instrument. more accurate than deflection types. Measurement  using an instrument as a physical means of determining a quantity or variable. Passive instruments For example, the Pokemon Website describes it as "constructed to synthesize the strengths of various Pokémon," in other words purposefully counterbalancing its traits with other opposing ones. In Null type instruments, a zero or null indication leads to the determination of the magnitude of the measurand quantity. A deflection-type instrument is therefore the one that would A null indicator may be a galvanometer, electrometer, telephone, or cathode-ray tube. 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. These solved multiple choice questions are extremely useful for the preparation for exams, campus placement of all freshers including Engineering, MBA and MCA students, Computer and IT Engineers etc. Answer to: A null type of instrument as compared to a deflection type instrument has a higher accuracy or a lower sensitivity? Systems Instrumentation Systems Elements of Instrumentation Systems Type of Instruments Performance Parameters Static characteristics of instruments Dynamic characteristics of instruments This topic is an introduction to the instrumentation and measurement systems used during changing or refining of raw materials till final product achieved in manufacturing or process industries. What are instruments? However, for calibration duties, The electrical properties of the materials largely, Definition of Measurement and Calibration, Ohm's Law | Basic Law of Electrical | Terms Related to Electrical. Answer. Example: Pressure measuring device The pressure of the fluid is translated into a movement of a pointer against scale. The pressure gauge is a good example of a deflection-type instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. Ohm's Law | Basic Law of Electrical | Terms Related to Electrical That is, if temperature, length and cross sectional area of conductor are not changed then, I ∝ V  or  I = V / R or  V=IR where, V=voltage between ends of the conductor in volts I=current through the conductor in amperes. It is far simpler to read the position of a pointer normally be used in the workplace. V - I  characteristics  If a curve is plotted between V and I it is found to be a straight line. If we use such kind instrument in ac circuit, the moving system will try to move forward and backward several times within a … As of version 0.10.0, the .instrument environment is located at the top level of the package. Only DC instruments In any instrument, if the deflection is directly proportional to the voltage or current to be measured, then they are suitable for dc measurement only. Only DC instruments In any instrument, if the deflection is directly proportional to the voltage or current to be measured, then they are suitable for dc measurement only. Graphic recorders and galvanometer recorders are the examples of these instruments. 2. is a null-type instrument. The pressure gauge is a good example of a deflection-type instrument, where the value of the quantity being measured is displayed in terms of the amount of movement of a pointer. reached. Calibration is a process of estimating the value of a quantity by comparing that quantity with given standard quantity. 2) They are readily used for measuring Disadvantages of Null - Type: 1) Due to addition of The pressure measuring device and the float-type petrol tank level indicator are example of A. Instrument: Define an instrument: Instrument can be defined as a device for measuring the value or magnitude of a quantity or variable. The devise that is used for measurement of certain physical quantity is called as measuring instrument. In a Null type Instrument, the quantity to be measured produces an effect that is compared with an already calibrated effect of another system. weights. 2. These are the top rated real world C# (CSharp) examples of MetadataType extracted from open source projects. Instrument Types and Performance Characteristics Digital Instruments. second type of instrument will normally be the more accurate. Active instruments. added until the piston reaches a datum level, known as the null point. A digital instrument has an output that varies in discrete steps and so can only have a finite number of values. Integrating instruments The total amount of either electricity or electrical energy supplied over a period of time is measured by these instruments. If we use such kind instrument in ac circuit, the moving system will try to move forward and backward several times within a … (b) An unknown emf (labeled script Ex in the figure) is connected as shown, and the point of contact along R is adjusted until the galvanometer reads zero. Example 7.1. Q. Q1. Fig. The primary_id for these can begin with 1 or 2 dots if you need to avoid overwriting another instrument. The analogue instruments indicate the magnitude of the quantity in the form of the pointer movement. active and passive instruments for a particular application involves carefully balancing the measurement resolution requirements against cost. The null condition depends upon some other known conditions. Fig. Fig. A method of measurement in which the measuring circuit is balanced to bring the pointer of the indicating instrument to zero, as in a Wheatstone bridge, and … The accuracy of the instruments is low. Pressure measurement is made in terms of the value of the weights active and passive instruments for a particular application involves carefully balancing the measurement resolution requirements against cost. calibration operations. Basic of Electrical,Power Electronics Theory,All the Detail of Power system, Electrical Machine Theory,Detail about Industrial Instrumentation. 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. The electronic instrument is based on electrical or electronic principles for their measurement. The following are the disadvantages of deflection type instruments. a deflection-type instrument, where the value of the quantity being Null Type Instruments In opposite to deflection type of instruments, the null or zero type electrical measuring instruments tend to maintain the position of pointer stationary. The potentiometer, a null measurement device. 2.1.2 Null-type and deflection-type instruments The pressure gauge just mentioned is a good example of a deflection type of instrument, If an, Ohm's Law | Basic Law of Electrical | Terms Related to Electrical Ohm's Law  Ohm's law states that the current through any conductor is directly proportional to the potential difference between its ends, if the physical conditions of the conductor do not change. Null-Type Method: A null-type device attempts to maintain deflection at zero by suitable application of a known effect opposing the generated by the measured quantity. 3. The DC potentiometer is an example of null type potentiometer. These instruments give output in terms of physical constant of the instruments. The V - I characteristics of it is shown in below figure. 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