File Name: use of measuring instruments and type of instruments .zip
Measuring Instruments plays a vital role in the Engineering Workshop. The Instruments duty is to measure the given specimen according to the given dimensions.
Basic classification of measuring instruments:. Mechanical instruments:- They are very reliable for static and stable conditions. The disadvantage is they are unable to respond rapidly to measurement of dynamic and transient conditions. Electrical instruments:- Electrical methods of indicating the output of detectors are more rapid than mechanical methods. The electrical system normally depends upon a mechanical meter movement as indicating device.
Basic classification of measuring instruments:. Mechanical instruments:- They are very reliable for static and stable conditions. The disadvantage is they are unable to respond rapidly to measurement of dynamic and transient conditions.
Electrical instruments:- Electrical methods of indicating the output of detectors are more rapid than mechanical methods. The electrical system normally depends upon a mechanical meter movement as indicating device. Electronic instruments:- These instruments have very fast response. For example a cathode ray oscilloscope CRO is capable to follow dynamic and transient changes of the order of few nano seconds 10 -9 sec.
Other classification of instruments Absolute instruments or Primary Instruments :- These instruments gives the magnitude of quantity under measurement in terms of physical constants of the instrument e. Tangent Galvanometer. These instruments do not require comparison with any other standard instrument. They are mostly used as means of standard measurements and are maintained lay national laboratories and similar institutions. Secondary instruments :-These instruments are so constructed that the quantity being measured can only be determined by the output indicated by the instrument.
These instruments are calibrated by comparison with an absolute instrument or another secondary instrument, which has already been calibrated against an absolute instrument. Working with absolute instruments for routine work is time consuming since every time a measurement is made, it takes a lot of time to compute the magnitude of quantity under measurement.
Therefore secondary instruments are most commonly used. The quantity to be measured by these instruments can be determined from the deflection of the instruments. Classification of Secondary Instruments :. They are :. Generally the magnetic effect and the electromagnetic induction effect are utilized for the construction of the commercial instruments. Some of the instruments are also named based on the above effect such as electrostatic voltmeter, induction instruments, etc.
We have the following instruments. Examples are ammeter, voltmeter, wattmeter etc. In principle, these are indicating instruments but so arranged that a permanent continuous record of the indication is made on a chart or dial. The recording is generally made by a pen on a graph paper which is rotated on a dice or drum at a uniform speed.
The amount of the quantity at any time instant may be read from the traced chart. Any variation in the quantity with time is recorded by these instruments.
Any electrical quantity like current, voltage, power etc. That is, these instruments totalize events over a specified period of time. No indication of the rate or variation or the amount at a particular instant are available from them. Some widely used integrating instruments are: Ampere-hour meter: kilowatthour kWh meter, kilovolt-ampere-hour kVARh meter. These instruments are most widely used in engineering practice because they are simple and inexpensive.
Also, time involved in the measurement is shortest. Examples are Ammeter, Voltmeter, Watt meter etc. Examples are dc and ac bridges and potentiometers. They are used when a higher accuracy of measurements is desired. Electrical Measurements. Search this site. Classification of Measuring Instruments. Essentials of Measuring Instruments. Basic classification of measuring instruments: 1.
Other classification of instruments:- 1. Under this heading, we have:. Under this category, we have:. Classification of Secondary Instruments : a Classification based on the various effects of electric current or voltage upon which their operation depend.
The instrument used for measuring the physical and electrical quantities is known as the measuring instrument. The term measurement means the comparison between the two quantities of the same unit. The magnitude of one of the quantity is unknown, and it is compared with the predefined value. The result of the comparison obtained regarding numerical value. This instrument is suitable for measuring the static and stable condition because the instrument is unable to give the response to the dynamic condition.
Roughness measurement examples. In contact-type instruments, the stylus top makes direct contact with the surface of a sample. The detector tip is equipped with a stylus, which traces the surface of the sample. The vertical motion of the stylus is electrically detected. The electrical signals go through an amplification and digital conversion process to be recorded. To precisely measure delicate shapes and roughness with a contact-type surface roughness tester, the radius of the stylus tip must be as small as possible with small contact pressure. A conical shape with a ballpoint tip is considered ideal for a stylus.
Types of Measuring Instruments and their Uses in Engineering Workshop [PDF] · Length is measured in centimeter (cm) · Mass is measured in grams (gm) · Time is.
Roughness measurement examples. With contact-type surface roughness instruments, a stylus tip makes direct contact with the surface of a sample. The detector tip is equipped with a stylus tip, which traces the surface of the sample and electrically detects the vertial motion of the stylus.
Some of these kinds of tools can be very sensitive, and slight variations in conditions can cause them to malfunction and deliver inaccurate results. Why is the proper care of measuring tools so important? Some of the benefits include the following.
Your email address will not be published. Required fields are marked *