## Ammeter Shunt –Construction and Calculation

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...

## Voltmeter Multiplier – Construction and Calculation

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...

## Working Principle of Moving Iron Instruments

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...

## Why Moving Iron Instrument Scale is Non-uniform?

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...

## What Happens if Ammeter Connected in Parallel and Voltmeter Connected in Series?

It is a well known fact that Ammeter is always connected in series with the element through which current is to be measured. Figure below shows two cases, in one case ammeter connected in series while in other case, ammeter is connected in parallel. As...

## Working Principle of Residual Voltage Transformer

A Residual Voltage Transformer is used to measure the residual voltage of three phase system during single phase fault. During normal operating condition, the summation of three phase voltage is zero but in case of single phase fault, the scenario changes and there exists a...

## Various Error in PMMC Instrument

Permanent Magnet Moving Coil or PMMC Instruments are the best for the measurement of DC quantities like voltage and current from accuracy point of view. But there are various factors due to which error in PMMC Instrument reading may develop. To investigate the main sources...

## PMMC Instruments – Construction and Working Principle

Permanent Magnet Moving Coil or PMMC Instruments are the most accurate type for the measurement of DC current or voltage. The working principle of PMMC instruments are same as that of d’Arsonaval type of Galvanometer, difference being that a direct reading instrument is provided with...