Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE) PDF Download

MEASUREMENT ERRORS

1. Ablosute Error. The difference between the measured value Am and the true alue A of the unknown quanity if known as the abloute error of measurement δA *i.e.dA = Am - A.

2. Relative Error is the ratio of absolute error to the true value of the quantity to be measured i.e.

r =δA / A =∈0 / A = absolute error/true value.

3. Gross Errors. In this category, errors occur because of mistakes in reading or using instruments and in recording and computing measurement results. these errors are usually because of human mistakes and may be of any magnitude can cannot be subjected to mathematical treatment.

4. Systematic Errors. Such error remain constant of change according to a definite law on repeated measurement of a given quantity. Such errors cab be evaluated and their influence on the measurement results a can be eliminated by introducing proper corrections. These errors are of two types namely

 (a) instrumental errors

 (b) environmental errors.

 Instrumental errors are inherent in the measuring instruments because of their mechanical structure and calibration or operation of the apparatus used. Environmental errors are introduced due to use of an instrument in different environmental conditions than in which it was assembled and calibrate. these errors are much more troublesome as these change with time in an unpredictable manner.

5. Random (or accidental) Errors. These error are of variable magnitude and sign and do not obey and known law. Presence of random errors becomes evident when different results are obtained on repeated measurements of one and the same quantity.

 Determination of Maximum systematic Error 

1. Sum of Two or More Quantities. Let the final result y be the sum of measured quantities u, v, and  z, each of which is subjected to possible systematic error ± δu, ±δv and ± δz r sp ectively, corres ponding limiting error δy is given by

  Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

2. Difference of two Quantities, Let y=u–v

  Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

3. Product of Two Quantities, Let y = u.v.z

  Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

4. Quotient of Two Quantities. Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

  Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

5. Power of factor. Ley y = un where n may be + ve or -ve, integral of fractional

  Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

6. Composite Factor. Let y = un vm

Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

Resolution and Sensitivity The resolution of discrimination of an instrument is the smallest change in the input signal (quantity under measurement) which can be detected by the instrument. it may be expressed as an actual value or as a fraction of percentage may be expressed as an actual value or as a fraction of percentage of the fullscal value.

The sensitivity is defined as the ratio of output signal or response of the instrument to a change of input signal or the quantity under measurement.

Accuracy and Precision Accuracy is a closeness with which the instrument reading approaches the true value of the variable under measurement while precision is a  measure of the reproducibility of the measurement i.e. precision is a measure of the degree to which successive measurements differ from one another. significant figures An indication of the precision of the measurement is obtained from the number of significant figures in which result is expressed. More the significant figures, greater the precision of measurement.

The document Measurement Errors | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE) is a part of the Electrical Engineering (EE) Course Electrical Engineering SSC JE (Technical).
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FAQs on Measurement Errors - Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

1. What are measurement errors in electrical engineering?
Ans. Measurement errors in electrical engineering refer to inaccuracies or deviations in the measurement of electrical quantities, such as voltage, current, resistance, or power. These errors can occur due to various factors, including instrument limitations, environmental conditions, human errors, or incorrect calibration.
2. How can instrument limitations contribute to measurement errors in electrical engineering?
Ans. Instrument limitations can contribute to measurement errors in electrical engineering by introducing inaccuracies in the measurement process. For example, an instrument may have a limited resolution, leading to rounding errors or uncertainties in the displayed value. Additionally, instruments may have inherent measurement uncertainties or non-linearities, which can further contribute to errors in the measured values.
3. What are some common sources of measurement errors in electrical engineering?
Ans. Common sources of measurement errors in electrical engineering include: 1. Noise interference: Electrical signals can be affected by external noise sources, such as electromagnetic interference (EMI) or radio frequency interference (RFI), leading to measurement errors. 2. Loading effects: When measuring a circuit's voltage or current, the act of connecting the measuring instrument can alter the circuit's behavior, leading to measurement errors. 3. Temperature variations: Changes in temperature can impact the characteristics of electrical components, causing measurement errors in resistance, capacitance, or other electrical parameters. 4. Signal distortion: Signal distortion can occur due to factors like transmission line losses, impedance mismatches, or improper grounding, resulting in measurement errors. 5. Human errors: Errors introduced by individuals during the measurement process, such as incorrect connections, misreading values, or improper use of instruments, can also contribute to measurement errors.
4. How can environmental conditions affect measurement errors in electrical engineering?
Ans. Environmental conditions can affect measurement errors in electrical engineering in several ways. For instance: 1. Temperature and humidity: Electrical components can be sensitive to temperature and humidity variations, causing changes in their electrical properties and introducing measurement errors. 2. Electromagnetic interference (EMI): Strong EMI sources in the environment, such as power lines or nearby electronic devices, can interfere with sensitive measurement instruments and distort the measured values. 3. Vibrations and mechanical stress: Vibrations or mechanical stress can impact the stability and accuracy of measurements, especially in cases where precise positioning or delicate connections are required. 4. Atmospheric conditions: In certain applications, atmospheric conditions like air pressure or altitude can affect the performance of electrical components or sensors, leading to measurement errors. 5. Contaminants and impurities: Presence of contaminants, such as dust, moisture, or chemicals, can degrade the performance of electrical components or introduce unexpected behaviors, resulting in measurement errors.
5. How can calibration help reduce measurement errors in electrical engineering?
Ans. Calibration plays a crucial role in reducing measurement errors in electrical engineering. It involves comparing the measurements of an instrument with a known reference standard and adjusting the instrument to minimize any discrepancies. Calibration helps in: 1. Correcting systematic errors: By calibrating an instrument, systematic errors or biases in the measurement can be identified and corrected, reducing the overall measurement errors. 2. Ensuring accuracy and traceability: Calibration ensures that the instrument's measurements are accurate and traceable to a recognized standard, providing confidence in the reliability of the measured values. 3. Minimizing uncertainties: Calibration helps in quantifying and minimizing uncertainties associated with the measurement process, leading to improved accuracy and repeatability. 4. Extending instrument lifespan: Regular calibration helps identify any gradual drift or degradation in an instrument's performance, allowing for timely maintenance or replacement, thereby reducing measurement errors over time. 5. Compliance with standards and regulations: Many industries and applications require adherence to specific measurement standards or regulations. Calibration ensures that the measurements meet these requirements, avoiding potential legal or compliance issues.
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