All About Electrical and Electronics Measurement Facts and Tutorials
It is important as an electrical engineer, we have a great knowledge how electrical or electronics measuring works, because the income of the electrical company depends on. listed below are key facts and tutorials that electrical engineer you should know.
A mirror is provided behind the pointer in measuring instruments to eliminate the reading errors, due to inclined observations, by removing parallel between the pointer and its image in the mirror.
Threshold of sensitivity with respect to instrument is the smallest signal that results in a detachable output.
Schering Bridge can be used to measure capacitance and its power factor.
Hay bridge is used to measure inductance of a high Q inductor.
Damping provides braking action on a meter pointer.
In moving coil meters, damping is provided by the aluminum frame.
Moving coil instruments are used in DC circuits only.
The sensitivity in accuracy of an instrument does not depend on hysteresis or dead bond, amplitude distortion and frequency response.
The sensitibity inaccuracy of a recording instrument means the maximum error in sensitivity displayed by a pen.
When using any instrument for measurement or testing an electrical circuit, your personal safety should be considered first.
The resolution of an indicating instrument is the smallest change in applied stimulas that indicates a detachable change in deflection.
The accuracy classes of industrial measuring instruments should be 1, 2.5, 2.5 and 5.
In measuring instrument, the internal resistance of ammeters should be very small, and that of voltmeters very high.
Meter accuracy is determined by full scale deflection.
The reliability of an instrument means degree to which as instrument's readability continues to remain within specific limits.
To reduce the effect of a voltmeter upon the circuit under test, we should get an instrument with a higher internal resistance.
To increase the range of a voltmeter a high resistance is connected in series.
The function of the zero adjust control in a multimeter is that the zero point is corrected with the help of this control.
If moving iron type ammeter is connected to a circuit, and we interchange its connected, then its reading will not change.
Eddy current damping methods is common in moving coil instruments.
The main reason for using springs in a measuring instrument is to control the pointer movement.
A moving iron type instrument has a nonlinear scale.
In moving coil instruments, the scale used is linear scale.
The function of a shunt in an ammeter is to by pass the current.
The shunt resistance in an ammeter is to bypass the current.
External shunts are generally used for measuring currents greater than about 30 ampere.
Induction type single phase energy meter is true watt hour meter.
A wattmeter can measure AC as well as DC power.
Meggar essentially is megaohmmeter. Meggar's operation is based upon moving coil meter.
If the aproximate value of the current to be measured is not known, the measurement should start on the highest range and then increase the range.
An electrodymic meter can be used to measure DC as well as AC voltage.
Meggar is an instrument to measure insulation resistance.
The cell used in a potentiometer is a lead accumulator.
A coil of high inductance equipment is not a part of meggar with a coil of high inductance.
The number of the coils in the meter of meggar is two.
With the measurement terminals open circuit, the infinity reading of meggar is due to currents in the coil connected across the measurement points.
Carey Foster Bridge is specially designed to determine the difference between two nearly equal resistances.
Maxwell bridge is used to measure inductance of a low Q inductor.
A multimeter consists of voltmeter, current meter and ohmmeter.
Sensitivity of a voltmeter is expressed as Ohms/Volt.
If a low voltage is measure on a higher scale of a voltmeter, the measurement would have low accuracy low resolution an low precision.
The disadvantage associated with an electro dynamic instrument are first it consumes more power second it has a low torque to
weight ration and third is its frequency range is low.
The simplest and most convenient form of detector used in a Wheatstone Bridge for audio frequency range is a pair of headphones
Inductance is measured in terms of capacitance and resistance by Anderson Bridge.
The potentiometer wire should have high specific resitance and low temperature coefficient.
Sensitivity of a potentiometer can be increased by increasing the length of potentiometer wire.
