Energy Meters are one of the important instrument to account for energy imported / exported in an industry. In Power Generating Stations, the cumulative reading of such energy meters are used for the calculation of total Million Units (MUs) of energy exported. On the basis...
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January 11, 2018 admin
Measurement and Instrumentation
17 Comments
Strain Gauge is basically a sensor used for the measurement of various physical parameters like stress, strain etc. The working principle of strain gauge is based on Piezoresistive Effect. This is why it is also often called Pizoresistive Gauge. When a metal conductor is stretched...
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January 7, 2018 admin
Measurement and Instrumentation
No Comment
Accuracy Limit Factor of Current Transformer is a very important factor while selecting a CT for protection purpose. A current transformer chosen for protection purpose are defined by protection class ‘P’. The whole and sole requirement of a protection class CT is to maintain its...
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January 6, 2018 admin
Measurement and Instrumentation
3 Comments
Instrument Safety Factor Instrument Safety Factor (ISF) is defined as the ratio of CT saturation current to its rated current. Suppose the CT ratio is 2000/1 and the CT gets saturated if there is flow of 10 kA current through its primary, then Instrument Safety...
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December 20, 2017 admin
Measurement and Instrumentation
1 Comment
Before discussing “Why PT/VT Secondary Terminal should not be Shorted?”, it is good to have a brief idea of Potential Transformers / Voltage Transformers. PTs/VTs are Instrument Transformer used for the purpose of protection and measurement. The construction of PT/VT is same as that of...
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December 16, 2017 admin
Measurement and Instrumentation
No Comment
Core Balance Current Transformer or CBCT is a ring type current transformer through center of which a three core cable or three single core cables of three phase system passes. This type of current transformer is normally used for earth fault protection for low and...
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November 9, 2017 admin
Measurement and Instrumentation
13 Comments
Ammeter Shunt is used for the measurement of heavy current using an Ammeter. Ammeter Shunt is basically a low resistance connected in parallel with the moving coil so that most of the current is bypassed by the Shunt and hence only a small current flows...
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November 9, 2017 admin
Measurement and Instrumentation
No Comment
A PMMC Instrument can be used as voltmeter by just connecting a series resistance with the moving coil. This series resistance is called Voltmeter Multiplier. This combination of moving coil and multiplier is connected across the point whose voltage is to be measured. There are...
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November 9, 2017 admin
Measurement and Instrumentation
No Comment
Moving Iron Instruments are the most common type of ammeter and voltmeter used at power frequencies in laboratories. These instruments are very accurate, cheap and rugged as compared to other AC instruments. Working Principle of Moving Iron Instruments: In Moving Iron Instruments, a plate or...
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November 9, 2017 admin
Measurement and Instrumentation
No Comment
The deflection of needle of moving iron instrument is given in terms of rms value of voltage or current. As the angular deflection of Moving Iron Instrument is proportional to square of operating current, therefore the instrument has basically square law response. Due to this...
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November 9, 2017 admin
Measurement and Instrumentation
4 Comments
