COMPARATOR

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17 Oct 2022

A comparator is device which is use to measurement of instuments.A comparator works on relative measurement.Itgives only dimensional differences in relation to dimension.Comparator compares the unknown dimensions of a part with some standard which represents the basic size and dimensional variations from master setting.A comparator is a device that compares two voltages or currents and outputs a digital signal indicating which is larger.The comparator has two analog input terminals.The comparator is very useful device to measure theinstrument. A comparator consists of a specialized high-gain differential amplifier.The characteristics of the comparator is the :-1) Robust in design & construction. 2) Quick indicating device. 3) Free from Backlash , wear effect and inertia. 4) Max. Compensation for Temperature effect.5) Linear scale and straight line characteristics.6) Indicator pointer should return to ‘zero’.7) Maximum versatility.8) Low Measuring pressure,these are the characteristics of camparator.There are three types of camparator 1.Dial indicator 2.Mechanical comparator.3.Pneumatic camparator.4. Electrical indicator.these are the types of camparator 1. Dial indicator:-The linear movement of the spindle is magnified by means of pinion and geartrain into rotation of pointer on the dials cale.The magnification depends upon thenumber of teeth on gear and pinion,also can be increased by increasing thelength of rack.This is generally used for inspection of small precision machinedparts/components.This type of comparator can be used with various attachments forvarious large number of workscan be used for measurement of roundness , flatness , straightness.The typical least count that can be obtained with dial indicators is 0.01mm.It measures the measurement in the range of 0.25 to 300 mm.Dial indicators are used primarily for measuring gauges and features, the dial test indicator is most often used for surface plate layout work or indicating measurements during machine setup.2:-Mechanical camparator:-Mechanical comparator is a measuring instrument and the mechanism of this instrument is in the form of tape spring twisted, and that is positioned in the middle part. The middle part of the mechanical comparator rotates through a fixed angle upon tension.Mechanical comparators are available having magnifications from 300 to 5000 to 1. These are mostly used for the inspection of the small parts of the machine to close linmits. A dial indicator or dial gauge is used as a mechanical .3.Pneumatic Comparator:-This camparator is also called as solex Pneumatic comparator.This camparator is produced by SOLEX AIR GAUGE LTD.This camparator is generally design for internal measurements.Sensitivity is depends upon the supply pressure ‘P’ must beconstant. Simple pressure regulator is used to control the air pressurein camparator.A pneumatic comparator is a precision device operated using a pneumatic system or comprssed air.Like other mechanical, optical, and electrical comparators, pneumatic comparators are also used to analyze the dimensional difference between the workpiece to be measured and the standard workpiece.4.Electrical camparator:-If the armature is centrally located between the coils, the inductance of both coils will be equal but in opposite direction with the sign change. Due to this, the bridge circuit of A.C. wheat stone bridge is balanced. Therefore, the meter will read zero value. But practically, it is not possible. In real cases, the armature may be lifted up or lowered down by the plunger during the measurement. This would upset the balance of the wheat stone bridge circuit. Due to this effect, the change in current or potential will be induced correspondingly. On that time, the meter will indicate some value as displacement. This indicated value may be either for larger or smaller components. As this induced current is too small, it should be suitably amplified before being displayed in the meter.The camparator is very useful device.the the main disadvantages of camparator are:-1.Accuracy of the comparator mainly depends on the accuracy of the rack and pinion arrangement,Any slackness will reduce accuracy.2.It has more moving parts and hence friction is more and accuracy is less.3.The range of the instrument is limited since pointer is moving over a fixed scale.The camparator is very useful device in measuring instruments like metrology lab and quality control department.The camparator is very useful device or instument.