Kelvin Bridge

Definition: The Kelvin bridge or Thompson bridge is used for measuring the unknown resistances having a value less than 1Ω. It is the modified form of the Wheatstone Bridge. What is the need of Kelvin Bridge? Wheatstone bridge use for measuring the resistance from a few ohms to several kilo-ohms. But error occurs in the …

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Three Phase Wattmeter

Definition: Three-Phase Wattmeter is used for measuring the power of the three-phase circuit. In three-phase Wattmeter, the two separate Wattmeter are mounted together in the single unit. Their moving coils are placed on the same spindle. Three-Phase Wattmeter has two elements. The single element is the combination of the pressure coil and the current coil. The …

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Volt-Ohm-Milli-Ammeter (VOM)

Definition: The multimeter or volt-ohm-milli-ammeter (VOM) is the type of meter which performs the multiple functions. In other words, in VOM the multiple measuring functions are combined in a single unit. The multimeter is used for measuring voltage, current and resistance. It contains the circuitry switch which makes the meter to operate like a voltmeter, …

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Phase Sequence Indicator

Definition: The instrument uses for determining the sequence of the three-phase system is known as the phase sequence indicator. The change in the sequence of the power supply changes the direction of rotation of the machine. Because of which the entire supply system will be affected. For proper connection, it is essential to know the …

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Capacitive Voltage Transformer (CVT)

Definition: The capacitive voltage transformer step-down the high voltage input signals and provide the low voltage signals which can easily measure through the measuring instrument. The Capacitive voltage transformer (CVT) is also called capacitive potential transformer The capacitive potential divider, inductive element and the auxiliary transformer are the three main parts of the capacitive potential …

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Weston Frequency Meter

Definition: The Weston frequency meter is a moving iron instrument used for measuring the unknown frequency of a signal. The frequency meter consists one inductive and one resistive coil. When the frequency of the signal varies from standard frequency, the current distribution across the coils becomes changes. Working Principle of Weston Frequency Meter The Weston …

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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 …

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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 …

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