If you are an electrical engineer than you must know how to connect various electrical instruments in a circuit, Specially measuring instruments. The most common instruments or measuring apparatus you must know about are Voltmeter, Ammeter, Energy meter and Watt meter.
Voltmeter : -
Voltmeter is a device that is used to measure voltage or potential difference across two given points. Essentially a voltmeter is nothing but a galvanometer with infinite resistance connected in series . This makes the resistance of an ideal voltmeter infinite .
Voltmeter is connected in parallel, this is shown below : -
As shown in image a voltmeter is connected in parallel or in shunt configuration, due to voltage division in series.
If we connect it in series high resistance of voltmeter will make the circuit insulating and no current will flow and the system will stop working.
Voltage Division in Series
If two resistances are connected in series the voltage given to the complete system is divided across resistances.
Let us consider two resistances with resistance R1 and R2, then total resistance of series configuration will be given by
R = R1 + R2
and Voltage across each resistance is give by
V1 = R1*V/R,
V2 = R2*V/R,
Here,
V1 is voltage across R1 and
V2 is voltage across R2.
The below Figure shows this more clearly.
Ammeter
: -Measure current ( general term ) or rate of flow of charge ( Technical meaning ) between two points on a conductor.
An Ammeter is connected in series because it has low resistance. Connection of an ammeter is shown below with circuit diagram : -
Watt Meter
: -A watt meter Measures power consumed by an apparatus in a given time. Normally watt meter gives reading in watt or kilowatt. Connection of watt meter is shown below : -
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