Measurement & instrumentation ppt

Prabhu Mike

MEASUREMENTS &

INSTRUMENTATION

R. Prabhu13291218-02-2015

2/18/2015

Prabhu Mike

TONG TESTERTong tester is used to measure voltage and current from the live supply wire.Construction:It consists of two clamps arranged in the form of ring. One is stationary and the other is movable due to the presence of spring.It is commonly used in industries.

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Prabhu Mike

Tong tester…

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Prabhu Mike

RECORDER

• Recorder is a device which records electrical and non electrical quantities as a function of time. Current and voltages can be recorded directly, while the non electrical quantities are recorded indirectly.

• Types of recorders: 1. Analog recorders 2. Digital recorders

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Prabhu Mike

• Analog recorders are further divided in to three types:

• 1. Graphic recorder a. strip – chart recorder b. circular chart recorder c. X – Y recorder• 2. Oscillographic recorder• 3. Magnetic – tape recorder a. Direct recorder b. F. M. recorder c. pulse modulation recorder2/18/2015

Prabhu Mike

X – Y RECORDER

• X-Y recorder is an instrument which gives a graphic record of the relationship between two variables. We may say X-Y recorder is one which records the variation of one physical quantity against another physical quantity.

• It is used to measure voltage, current, frequency, power factors etc….

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Prabhu Mike

Construction:

• X-Y recorder consists of a pair of servo-systems, driving a recording pen in two axis on stationary paper chart. Attenuators are used to bring the input signal to the levels acceptable by the recorder.

• Two input signal are applied to the two channels of X input & Y input.

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Prabhu Mike

X – Y RECORDER

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Prabhu Mike

Applications

o The X-Y recorders are used in laboratories and industrial process control. Some of the uses are listed.

o Speed – Torque characteristics of motor.o Lift – Drag wind tunnel rest.o Regulation curves of power supplies.o Plotting stress – strain curves.o Hysterisis curves.

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Prabhu Mike

SINGLE PHASE ENERGY METER

• There are four main parts of the operating mechanism in a energy meter. They are

(1) Driving system (2) Moving system (3) Braking system (4) Registering system

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Prabhu Mike

Driving system

• The driving system of the meter consists of two electromagnets. They are

1. Series magnet 2. shunt magnet• The electromagnets is made up of silicon steel

lamination. The coil of series magnet is excited by the load current. This coil is called current coil. The coil of shunt magnet is connected across the supply. This coil is called the pressure coil.

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Prabhu Mike

SINGLE PHASE ENERGY METER

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Prabhu Mike

Moving system

• This system consists of an aluminium disc mounted on spindle. This disc is positioned in the air gap between series & shunt magnets.

• The spindle top end is engaged in a bearing cup and the spindle rests and runs on a hardened steel pivot. The threaded portion on top of the spindle will engage a pinion of the energy recording mechanism.

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Prabhu Mike

Construction

• Braking system: The disc moves in the gap between the poles

& experiences an eddy current braking.• Registering (counting) mechanism: The function of a registering mechanism is

to record continuously a number which is proportional to the revolution made by the moving system and hence the energy in kWH.

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Prabhu Mike

Digital energy meter

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Prabhu Mike

MEGGER

• The megger is an instrument used for the measurement high resistance and insulation resistance.

• Construction: There are two pairs of permanent magnet,

one set for ohm meter side and the other for the generator. The moving coil consists of three coils namely.

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Prabhu Mike

Cont….

(a) control coil (b) deflecting coil (c) compensating coil• The unknown resistance is connected

between the terminals L & E (line & earth).• When the pointer indicate ‘0’ hence the

resistance is very low resistance value.

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Prabhu Mike

Megger

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Prabhu Mike

Thank you

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