Electromechanical meters, Electrical Engineering

Assignment Help:

Electromechanical Meters

Electromechanical energy meters are based on the Ferraris Principle (see note in the margin). The working of these meters is explained.

Working of Electromechanical Meters

The meters have a revolving metallic disc mounted on jewel bearings or magnetic suspension bearings. The display is cyclometer or mechanical counters and accuracy is classically 1% or 2% (class 1.0 or 2.0). They  cater  to  limited  tariffs  applicable  majorly  to  1-phase  or  3- phase direct connected segment (whole current meters).The electromechanical induction meter operates through counting the revolutions of the disc that rotates at a speed proportional to the power consumed. 

The number of revolutions is, therefore, proportional to the energy usage.  The metallic  disc is acted upon through three magnetic fields,  one  proportional  to the voltage,  the other  to the current  and  a third  constant  field  supplied  by  a  permanent   magnet.  One  of  the varying  fields  induces  currents  in  the  metallic  disc,  that  are  then acted upon through the other varying field to produce a torque.

This  results  in  the  torque  being  proportional  to  the  product  of  the current  and voltage,  that is power.  As the metallic disc rotates through the permanent magnetic field, eddy currents are again produced that dissipate energy (because the disc has some resistance) and act to slow the rotation. This drag is proportional to the rotation speed. The equilibrium among the applied torque and the drag results within a speed proportional to the power. The rotating disc in this category of meter is, actually,  an  electric  motor  of  a category  known as  a reluctance  motor  or  eddy current motor. It consumes a little amount of power, classically around 2 W.


Related Discussions:- Electromechanical meters

Determine voltage in given figure, Q. An n-channel JFET having V P = 3.5 V...

Q. An n-channel JFET having V P = 3.5 V and I DSS = 5 mA is biased by the circuit of Figure with V DD = 28 V, RS = 3000 , and R 2 = 100 k. If the operating point is given by

Find the efficiency of the transformer, Q. Athree-phase, 600-kVA, 2300:230-...

Q. Athree-phase, 600-kVA, 2300:230-V,Y-Ytrans- former bank has an iron loss of 4400 W and a full- load copper loss of 7600 W. Find the efficiency of the transformer for 70% full lo

History of computers , History of Computers To understand the  inventi...

History of Computers To understand the  invention of microprocessor we have  to see the  history  of computer  first. The growth  the computers  is divided in  different  gener

Uses of zener diode, Uses of Zener Diode Zener diodes are extensively...

Uses of Zener Diode Zener diodes are extensively used as voltage references and like shunt regulators to regulate the voltage across small circuits. While connected in parall

Find the number of possible station frequencies, Q. Find the number of poss...

Q. Find the number of possible station frequencies in the AM broadcast system in the United States

Find instantaneous electromagnetic torque, Consider an elementary two-pole ...

Consider an elementary two-pole rotating machine with a uniform (or smooth) air gap, as shown in Figure, inwhich the cylindrical rotor ismountedwithin the stator consisting of a ho

What are shift registers, What are shift registers? Design a 8 bit shift re...

What are shift registers? Design a 8 bit shift register with features like PISO, SISO, SIPO and PIPO.

Explain the suitability of aluminium, Explain the suitability of aluminium ...

Explain the suitability of aluminium  that is used as electrical conducting materials. Aluminium : Conductors are appropriate for ambient and very high temperature. Use of alu

V-i characteristics - power semiconductor devices , V-I Characteristics ...

V-I Characteristics  In the  normal  mode of  operation of an IGBT  a positive  voltage is applied to the collector relative to emitter. When  the gate is at zero potential wi

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd