# Electrical Terms

## Torque/Weight Ratio of an Indicating Instrument

Definition: The ratio of torque to the weight of the moving part of an instrument is known as a torque/weight ratio. It indexes the performance of the instrument. The higher value of torque/weight ratio shows that the instrument has good performances. The value of torque/weight ratio of the moving part of the instrument should not be …

## Construction of Potential Transformer

The potential or voltage transformer is a step-down transformer used for transformation of voltage from a high value to fractional value. The measuring instrument like ammeter, voltmeter, wattmeter, etc. designs for low voltages. If the measuring apparatus connects to the high voltage lines for measurement, the devices may get burned or damage. Thus, the potential …

## Thermocouple

Definition: The thermocouple is a temperature measuring device. It uses for measuring the temperature at one particular point. In other words, it is a type of sensor used for measuring the temperature in the form of an electric current or the EMF. The thermocouple consists two wires of different metals which are welded together at …

## Limiting Error

Definition: The limited deviation of the measured value from the true value is known as the limiting error or guarantee error. Such type of error is fixed on the instrument. The magnitude of the limiting error depends on the design, material and the workmanship used for the construction of the instrument. For obtaining a high degree …

## Differential Voltmeter

Definition: The voltmeter which measures the difference between the known and the unknown voltage source is known as the differential voltmeter. It works on the principle of comparison between the reference and the unknown voltage sources. The accuracy of the differential voltmeter is very high.The principle of operation of the differential voltmeter is similar to …

## Rectifier Type Instrument

Definition: The instrument which uses the rectifying element for measuring the voltage and current is known as the rectifying instruments. The rectifying element converts the alternating current to the direct current which indicates by the DC responsive meter. The PMMC uses as an indicating instrument. The sensitivity of the rectifying instruments is high as compared …

## Electrothermal Instrument

Definition: The instrument whose working depends on the heating effects of the measuring current is known as the electrothermal or electrothermic instrument. This device is used for measuring the high-frequency current. The most significant advantage of this type of instrument is that it measures the high range frequency current more than the Moving Iron and …

## Classification of Measuring Instruments

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 …

## Electrodynamometer Wattmeter

Definition: The instrument whose working depends on the reaction between the magnetic field of moving and fixed coils is known as the Electrodynamo-meter Wattmeter. It uses for measuring the power of both the AC and DC circuits. The working principle of the Electrodynamometer Wattmeter is very simple and easy. Their working depends on the theory …

## Ballistic Galvanometer

Definition: The galvanometer which is used for estimating the quantity of charge flow through it is called the ballistic galvanometer. The working principle of the ballistic galvanometer is very simple. It depends on the deflection of the coil which is directly proportional to the charge passes through it. The galvanometer measures the majority of the charge …