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# Instrumentation

## Ohmmeter Basic Concepts and Working Principle

Ohmmeter Definition An ohmmeter is an instrument used to measure the resistance. It is an instrument containing a voltage source and a meter directly calibrated in ohms. Series Ohmmeter One type of ohmmeter is the series ohmmeter, so called because the meter movement is in series with the source of …

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## Digital Voltmeter Circuit and Working Principle

In digital voltmeters, input quantity is a voltage or is converted into a voltage. Normally, digital voltmeters are abbreviated as DVM. The process by which a DVM converts the analog input into digital output is known as analog to digital conversion. The basic conversion processes are the comparison and voltage …

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## Digital Frequency Meter Circuit Diagram and Working Principle

The frequency of periodic electric voltage or current can be determined directly by the use of a frequency meter or indirectly through a comparison with a known frequency. One of the many frequency meters that directly indicates frequency is reed –type meter of the following figure. Fig.1: (a) Reed-Type Meter …

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## Oscilloscope Basics | What is an Oscilloscope

“Oscilloscope is most widely used to display amplitude and period of the signal as well as the shape of the wave.” Anything can be measured on the two-dimensional graph drawn by an oscilloscope. Normally, voltage is displayed on the vertical, or Y-axis and time on the horizontal, or X axis …

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## Potentiometer Variable Resistor Working Principle

A potentiometer or a rheostat is an instrument used to measure and compare potentials without drawing any current from the circuit. Potentiometer Principle The potential difference across any length of wire of uniform cross-section area is directly proportional to its length where a constant current flows through it. A potentiometer consists …

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## Wheatstone Bridge Circuit Theory and Working Principle

Wheatstone bridge is used to measure unknown resistance and is defined by the circuit of the following figure. In above Figure, R1, R2, and R3 are known resistances and Rx is the resistance whose value is to be determined. At least one of the known resistances is variable. The variable resistance is …

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## AC Energy Meter Working Principle

Energy is the product of power and time and is measured in watt-seconds or Joule. Since the voltage and current in a DC circuit are constant values, the energy is easily computed from a measurement of power and time, $W=Pt~~~~~~~~~~Joule$ Where W is in watt-seconds or Joules, P in watts …

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## Power Measurement In a Three-Phase System using Wattmeter

Wattmeter is an instrument, used to measure power in a circuit using current and voltage of the circuit. The wattmeter is essentially an electrodynamic mechanism, in which the stationary and movable coils separately measure the current and voltage of the circuit, as shown in Fig. The stationary coil is designed …

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## Voltmeter-Definition and Working Principle

A voltmeter is a basic device used for the measurement of electric potential or voltage, in volts. As discussed in ammeter section, any basic meter mechanism has a voltage Vm across its terminals when a full-scale current Im, flows through the meter. It follows that basic meter mechanism can be calibrated …

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## Ammeter- Definition and Working Principle

An Ammeter is a device used for the measurement of current in amperes. When the current in a circuit is substantially less than an ampere, its value is determined by the use of a milliammeter or micro-ammeter, which measures full-scale currents in milli-amperes or microamperes, respectively. The symbol for the ammeter …

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