power and energy measurement

INDUSTRIAL INSTRUMENTATION

POWER AND ENERGY MEASUREMENTS

M. Awais Yaqoob2011-ch-32

(University of Engineering and Technology, Lahore)

2

SYNOPSIS

Power MeasurementEnergy Measurement

Danish Tanvir (2008-chem-05)

Danish Tanvir (2008-chem-05) 3

POWER MEASUREMENT


POWER MEASUREMENTIn a direct current circuit it can

be done with the help of a voltmeter, ammeter and is computed by using a derivative of Ohm's law

P = VI = I2R = V2/R

In an AC circuit ,the average power is given by

Pavg = VI cosφ


BOLOMETERA device for measuring the power of

incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance.

APPLICATIONS: It is used to measure very low

powers. It is used to measure radiation of

sub millimeter wavelengths.


TYPES OF BOLOMETER

BOLOMETER

MICROBOLOMETER HOT ELECTRON BOLOMETER


MICROBOLOMETER


HOT ELECTRON BOLOMETER

The hot electron bolometer (HEB) operates at cryogenic temperatures, typically within a few degrees of absolute zero. At these very low temperatures, the electron system in a metal is weakly coupled to the phonon system.


CALORIMETER A device used to measure the quantity of

heat flow in a chemical reaction.The calorimeters are the most accurate of all instruments for measuring high power.


TYPES OF CALORIMETER

CALORIMETER

STATIC CALORIMETE

R

BOMB CALORIMETE

R

THROTTLING CALORIMETE

R


STATIC CALORIMETER


BOMB CALORIMETERIt is used to measure heat flows for gases and high temperature reactions.


THROTTLING CALORIMETERAn instrument utilizing the

principle of constant enthalpy expansion for the measurement of the moisture content of steam; steam drawn from a steam pipe through sampling nozzles enters the calorimeter through a throttling orifice and moves into a well-insulated expansion chamber in which its temperature is measured


WATTMETERAn instrument for measuring the

electric power in watts of any given circuit.

WATTMETER

ELECTRODYNAMIC

WATTMETER

ELECTRODYNAMOMETE

R

ELECTRONIC WATTMETER


ELECTRODYNAMICWATTMETERIt consists of two coils, a current

is allowed to flow through one coil that generates an electromagnetic field around the coil. The strength of this field is pointed by the needle attached with the other coil that has a high-value resistor connected in series with it to reduce the current that flows through it.


ELECTRODYNAMOMETERIt has a fixed coil which is surrounded at

right angle by the second coil i.e suspended by silk fibres, and to the coil is also attached a spiral spring the other end of which is fastened to a torsion head. If then the torsion head is twisted, the suspended coil experiences a torque and is displaced through an angle equal to that of the torsion head.


ELECTRONIC WATTMETER

Electronic wattmeters are used for direct, small power measurements or for power measurements at frequencies beyond the range of other types of wattmeters.


ENERGY MEASUREMENT


ENERGY MEASUREMENTEnergy creates the power to drive

tools and machines, to process materials into manufactured products and to create structures.

Energy= power × timeWhere power is equal to the

product of voltage and current.So, Energy=V×I×t


ENERGY METERS Energy meters are the

instruments basically used to measure the quantity of electric energy supplied to a circuit in a given time.

Basically, there are two types of energy meters:

D.C. meters A.C. meters


D.C. ENERGY METERSD.C. ENERGY METERS

Electrolytic Meters

Motor Meters

Clock Meters

Intermittent

Registering Meters


ELECTROLYTIC METERSElectrolytic meters are

exclusively ampere-hour meters, measuring electric quantity directly and electric energy only indirectly, on the assumption that the pressure of the supply is constant. It has further some types:

Edison meterC. O. Bastian's meter


MOTOR METERSAn integrating meter which has a

rotor, one or more stators, a retarding element which makes the speed of the rotor proportional to the quantity (such as power or current) whose integral over time is being measured, and a register which counts the total number of revolutions of the rotor.


CLOCK METERSSuppose there are two pendulum clocks,

geared to a single counting mechanism which records the difference in the rates of going of the two clocks,one having an ordinary pendulum and the other having a pendulum consisting of a fine coil of wire through which a current is passed proportional to the potential difference of the supply. Below this pendulum let there be placed another coil through which passes the current to be measured


INTERMITTENT REGISTERING METERS

A clock motion electrically driven is made to take readings at definite intervals - say, every five minutes - and to add up these readings upon a set of registered dials. The arrangement therefore integrates the ampere-hours or watthours.


A.C. INDUCTION METERSThese meters only apply in case

of alternating current supply.There are two types of induction

meters:

SINGLE PHASE INDUCTION METER

THREE PHASE INDUCTION METER


SINGLE PHASE INDUCTION METER


THREE PHASE INDUCTION METERUse of additional voltage and

current coils.The amount of energy

represented by one revolution of the disc is denoted by the symbol Kh which is given in units of watt-hours per revolution.

P=3600*Kh/t