Describe systematic errors in measuring instruments. 

1 Answer

Answer :

Systematic errors: - 

➢ Instrumental Error: These errors are caused due to the mechanical structure of measuring instrument. 

a) Inherent shortcomings of instruments: Instrument may read too low or too high. 

b) Improper use of instruments: Improper handling e.g. overloading, overheating, failure to adjust zero, use of high resistance leads. 

c) Loading effect: cause distortion in original signal. 

➢ Environmental Error: These are because of surrounding conditions such as temperature, pressure, humidity, dust, vibrations, or external magnetic fields or electrostatic fields. 

➢ Observational Error: Parallax errors, incorrect multiplying factor. 

Related questions

Description : List three types of errors in measuring instruments. Give reasons of occurring for any one of them.

Last Answer : Types of errors in measuring instruments:  A) Gross error: These are due to mistakes on the part of person using the instrument.  B) Systematic Error: i) Instrumental Error: These ... multiplying factor.  C) Random error: These persist even after gross and systematic errors are removed.

Last Answer : Systematic errors are instrumental errors, environmental errors, observational errors.

Description : Give the classification of the errors used in measuring instrument & state the reason for their occurrence.

Last Answer : Types of errors in measuring instruments:  A) Gross error: These are due to mistakes on the part of person using the instrument.  B) Systematic Error:  i) Instrumental Error: These ... multiplying factor.  C) Random error: These persist even after gross and systematic errors are removed. 

Description : What arc the errors occurring in measuring devices due to stray magnetic field and temp '? Explain how to compensate them.

Last Answer : 1. Error due to stray magnetic fields-   Main magnetic field gets disturbed by external magnetic fields known as stray magnetic fields.  2. Compensation technique   To avoid this error, ... resistance alloy having a negligible resistance temp coefficient in the ratio of 1:10 for pressure coil 

Description : calibration and the need of calibration for measuring instruments.

Last Answer : Calibration - It is a process of estimating the value of a quantity by comparing that quantity with a standard quantity.    Need of calibration: - Calibration defines the accuracy and ... aim of calibration is to minimize any measurement uncertainty by ensuring the accuracy of test equipment.

Description : Explain the essential toques in analog type measuring instruments.

Last Answer : List of torques in analog instruments:  1. Deflecting torque  2. Controlling / Restraining torque.  3. Damping torque.  1. Deflecting torque: To create deflection proportional to ... the speed higher will be the damping torque bringing the pointer to the equilibrium position quickly. 

Description : State two purposes of calibration of measuring instruments.

Last Answer : Purposes of calibration of measuring instruments: - The purpose of calibration is to ensure that readings of an instrument are consistent with other instruments. It is also important in determining the ... will need to be calibrated periodically to make sure it can function properly and safely. 

Description : Define following terms related to measuring instruments: i) Sensitivity ii) Selectivity.

Last Answer : i) Sensitivity: It is the ratio of the change in output signal to the change in input signal of quantity being measured.  ii) Selectivity: It is the term to describe fulfillment of the requirements of measurement by an instrument to be suitable for use in a given situation. 

Description : List out any four effects of electric current used in measuring instruments & write name of meter working on it.

Last Answer : Effects of Electric Current used in measuring instruments:  1. Magnetic Effect: PMMC and Moving Iron type Ammeters, voltmeter and Dynamometer type wattmeters etc.  2. Electromagnetic induction ... . Electrostatic effect: Voltmeters.  5. Hall Effect: Flux meter, Poynting vector wattmeter.

Description : List any four effects employed in measuring instruments.

Last Answer : Effects Employed in Measuring Instruments: 1. Magnetic Effect 2. Electromagnetic induction 3. Heating effect 4. Electrostatic effect 5. Hall Effect 

Description : Electrical Measuring Instruments

Last Answer : Electrical Measuring Instruments

Description : Describe spring control method of producing controlling torque in measuring instrument. Write any two properties required for spring material.

Last Answer : A)Spring control method: As shown in the figure, the inner ends of the both springs are attahced to the spindle, while outer end of upper spring is attached to the lever and outer ... of spring material: 1.Non Magnetic material 2.Low specific resistance 3.Low temperature coefficient of resistance

Description : State any four errors that occur in dynamometer type wattmeter

Last Answer : Errors that occur in dynamometer type wattmeter: 1. Errors due to method of connection. 2. Error due to pressure coil inductance. 3. Error due to pressure coil Capacitance. 4. Error due to mutual ... Error due to eddy currents. 7. Temperature error. 8. Error due to vibration of moving system

Description : State various types of errors in wattmeter.

Last Answer : Types of Error in wattmeter: 1. Errors due to method of connection. 2. Error due to pressure coil inductance. 3. Error due to pressure coil Capacitance. 4. Error due to mutual inductance effect. 5. ... . Error due to eddy currents. 7. Temperature error. 8. Error due to vibration of moving system.

Description : List the different errors in wattmeter & explain compensation for it.

Last Answer : Errors in Wattmeter Compensation method Error due to connection method To overcome this error, wattmeters are provided with additional compensating winding which is connected in series with ... due to friction The weight of moving system be reduced to minimum possible.

Description : List any four errors in induction type energy meter. Give method of compensation for each.

Last Answer : Errors in Induction Type Energy Meter with their Compensation:  1) Error due to friction: This error can be compensated by the additional shading band provided on the shunt electromagnet.  2) Phase ... error: This error can be compensated by providing a flux diverter' to the current magnet. 

Description : different types of errors occurs in measurement.

Last Answer : Generally errors are classified into three types: systematic errors, random errors and blunders. 1) Gross Errors 2) Random Errors 3) Systematic Errors Instrumental Errors Environmental ... to wrong observations or reading in the instruments particularly in case of energy meter reading. 

Description : What are the factors influencing measurement errors?

Last Answer : The factor influencing measurement errors are accuracy, precision, range and bandwidth, sensitivity, resolution and uncertainty.

Description : Gross errors occur in measurements because of (A) disturbances about which we are unaware. (B) human mistakes. (C) inherent shortcomings in the instrument. (D) loading effects on the meters.

Last Answer : Gross errors occur in measurements because of human mistakes.

Description : Name the different torque and their function in measuring instrument.

Last Answer : List of torques in analog instruments:  1. Deflecting torque  2. Controlling / restraining torque.  3. Damping torque.  1. Deflecting torque:  - To create deflection of pointer ... .  - Bring the pointer to standstill quickly.  - To minimize oscillations about final position. 

Description : Explain magnetic effect employed in measuring instrument.

Last Answer : Magnetic Effect:  I) In PMMC meters:  ➢ When a current is passed through a conductor, magnetic field is produced round the conductor. Due to this field when current ... field it experiences a mechanical force.  Examples: Electrodynamometer type instruments, Induction type instrument. 

Description : State the function of controlling torque in electrical measuring instrument.

Last Answer : Function of controlling torque  1. The function is to opposes the deflection force and increases with the increase in the deflection of the moving system, to limit its movement. 2. and brought ... set a position where the two opposing forces i.e. deflection and controlling forces are equal. 

Description : Define: (i) Resolution, (ii) Calibration, with reference to electrical measuring systems.

Last Answer : Resolution The smallest increment in input (the quantity being measured) which can be detected with certainty by an instrument is called its resolution or discrimination.  OR It is ... the measuring instrument with standard instrument to find out the error in the instrument under test.

Description : Why energy meter is integrating type measuring instrument?

Last Answer : Energy Meter is Integrating Type Measuring Instrument: Energy meter is used for measurement of energy, which is obtained by integration (summation) of power supplied over the particular time duration, hence it the integrating type measuring instrument. 

Description : Compare analog and digital instruments .

Last Answer : Parameter Analog Instrument Digital Instrument  1 Principle The instrument that displays analog signals is called as on analog instrument.  The instrument that displays ... , etc. Logical analyzer, signature analyzer, computers, microprocessor based instruments, etc. 

Description : Advantages of digital instruments

Last Answer : 1. They are having high input impedance, so there is no loading effect 2. They are having higher accuracy 3. An unambiguous reading is obtained 4. The output can be interfaced with external equipment 5. They are available in smaller size . 

Description : State the meaning of secondary instrument. Classify secondary instruments.

Last Answer : Secondary instruments: - Gives reading directly of the quantity being measured. - Calibrated with respect to absolute instruments  Classification of Secondary instruments:  1. Depending on the ... on permissible error: i) Standard meters ii) Substandard meters iii) First grade instruments.

Description : Compare primary and secondary instruments.

Last Answer : Primary instruments  Secondary instruments  Gives magnitude of quantity in terms of physical constants of instrument  Gives reading directly of the quantity measured.  Need no calibration  ... .  e.g. magnetic meter, induction meter, hotwire meter and electrostatic meter 

Description : State the material used for moving coil and former for PMMC instruments. 

Last Answer : Material Used for Moving Coil and Former for PMMC Instruments:  Material used for moving coil: Copper  Material used for Former: Aluminium

Description : Write a short note on Measuring Flask

Last Answer : Measuring Flask : Flask is laboratory vessels (container). The flask is made of plastic or glass. They are of different sizes and shapes. In school laboratory, 50ml, 100ml, 250ml, 500ml & 1000ml ... of different sizes and shapes. In laboratory 10ml to 25 ml pipette of glass or plastic are used.

Description : What are the test and measuring instrument required in an Electrical depots?

Last Answer : Ans. Following are the test and measuring instruments required in an Electrical depots. a. Test lamp b. Line Tester c. Continuity tester d. Volt meter e. Ammeter f. Earth megger g. Megger h. Lux meter i. Power analyzer j. Infrared thermometer

Description : When measuring insulation resistance of cables using d.c. source, the galvanometer used should be initially short circuited because  (A) Cables have a low value of capacitance which draws a high ... high value of charging current (D) Cables have a low value of capacitance and initial resistance

Last Answer : When measuring insulation resistance of cables using d.c. source, the galvanometer used should be initially short circuited because Cables have a high value of capacitance which draws a high value of charging current

Last Answer : The desirable static characteristics of a measuring system are accuracy, sensitivity and reproducibility.

Last Answer : For measuring a very high resistance we should use Meggar.

Last Answer : For measuring current at high frequency we should use thermocouple instrument.

Last Answer : String efficiency is used for measuring the degree of utilization of SCR.

Description : List of Scientific Instruments

Last Answer : Hydrometer measures humidity Barometer measures atmospheric pressure Purity of milk is measured by lactometer Fathometer measures the depth of oceans. Sextant is used for measuring ... regulate the temperature to a particular degree. Viscometer: is an instrument to measure viscosity.

Description : State the effect of dead zone on instruments.

Last Answer : It is the largest change in input during which the output remains constant. So during dead zone, even if input changes, output remains the same.

Description : Define: i) Range ii) Span of instruments

Last Answer : i) Range: It is defined as the difference between Greatest and Smallest value of the data or reading of the instrument.  ii) Span: It is defined as the algebraic difference between the upper and lower range values

Description : Permanent magnet moving coil instruments are used for

Last Answer : PMME are mostly used for measuring voltage and current.

Description : The use of _____ instruments is merely confined within laboratories as standardising instruments.

Last Answer : The use of absolute instruments is merely confined within laboratories as standardizing instruments.

Last Answer : Commonly used instruments in power system measurement are induction.

Last Answer : Operating torques in analogue instruments are deflecting, control and damping.

Last Answer : The power factor of a single phase load can be calculated if the instruments available are three ammeters or three voltmeters.

Last Answer : The switch board instruments should be mounted in vertical position.

Last Answer : In the majority of instruments, damping is provided by eddy currents.

Last Answer : According to application, instruments are classified as switch board, portable.

Last Answer : The use of absolute instruments is merely confined within laboratories as standardizing instruments.

Description : What do you mean by secondary instruments?

Last Answer : The instruments which will give the direct readings are called secondary instruments

Description : Standard Commands for Programmable Instruments (SCPI)

Last Answer : Standard Commands for Programmable Instruments (SCPI) SCPI stands for Standard Commands for Programmable Instruments it is often pronounced as Skippy. SCPI is a instrument language that control the ... is for storing data in instrument. Display : for presentation.