In other words, the power factor influences the speed, and the moving element disk rotates with a speed proportional to true power. May 15, 2018 now there are two types of power factor meterselectrodynamometer type. The suspension system provides excellent reproducibility without friction, and. Moving iron type meter a rotating iron magnetic field b number of. Moving iron and pmmc instruments can be distinguished from each other by looking at. Application applicable standards scale and pointer mechanical data the moving coil indicators and a phase angle adjuster are used to monitor changing power factor conditions on irreversible balanced. Why is moving iron used in the measuring of power and power.
In power meters and pover factor meters, current circuits and voltage. Due to square low response, the scale of the moving iron instrument is nonuniform. In a moving iron meter, the deflecting torque is proportional to. Deflection torque is proportional to the square of the current. Electrical measurements course introduces the basic principles of all measuring instruments. The force of attraction depends on the strength of the magnet field.
The instrument in which the moving iron is used for measuring the flow of current or voltage is known as the moving iron instrument. Moving iron ammeters and voltmeters are manufactured, mainly for measurements in 50hertz ac circuits. Movingiron instrument article about movingiron instrument. Special purpose measuring instruments mcqs with answers. The period during which the power to the traction motor is cutoff is known as. The moving iron vane meter operates on the principle of magnetic. Permanent magnet moving coil instruments pmmc the permanent magnet moving coil instruments are most accurate type for direct current measurements. Class 1 overshoot 33% externaltemperature influence 0.
While types of frequency meters can be damaged by transient supply voltage spike, crompton instruments 00741 frequency meters. These power factor meters consist of a moving iron pointer. The power factor meter has three fixed coils, and their axes are 120. Power factor in electrical energy management course content what is power factor. Versions to reflect typical voltage transducer ratios in marine applications complete the range. Oct 21, 2016 before answering your question let me explain the working principle of both moving coil and moving iron instruments that will give you a basic idea. It works on the principle that the iron place near the magnet attracts towards it. In this case the value of voltmeter multiplier which needs to connect in series with the moving coil can be calculated from equation 1 and 2. The moving iron instrument is divided into two categories. Standard dials are white matte with black printed scales and bar knife. In a moving iron ammeter, the field coil is connected in series to the circuit containing the current to be measured. Now there are two types of power factor meterselectrodynamometer type. Nov 09, 2017 lets assume that the moving coil of voltmeter can sustain a voltage of 0. They are the rotating magnetic field to some alternating fields.
Rotating field power factor meter the following are the essential feature of the rotating magnetic field. Rotates in both clockwise and anticlockwise direction alternately. A range of 48, 72, 96 and 144 mm din style panel meters measuring all electrical parameters and featuring moving coil or moving iron movements. Electrodynamometer type instruments construction and. This iron tends to move inward that is from weaker magnetic field to stronger magnetic field when current flowing through the coil. Operational frequency range of these meters is 10100 hz, but as to achieve best possible accuracy, it is best to inform of frequencies other than within the range of 5060 hz when placing the order.
The range offers iron vane and moving coil ac and dc ammeters and voltmeters. Moving iron power factor meter are suitable for 3 phase balanced circuits. Controlling torque increases with the deflection of the moving system so that the final position of the pointer on the scale will be according to the magnitude of an electrical quantity i. It is a horseshoe shaped permanent magnet with soft iron pole pieces attached to it. Moving iron instruments construction and basic principle operation in moving iron instruments the movable system consists of one or more pieces of speciallyshaped soft iron, which are so pivoted as to be acted upon by the magnetic field produced by the current in coil. Multiple choice questions and answers on measurement and. Moving iron ac ammeters for direct ac currents or ct connections. Multiple choice questions and answers on measurement and instrumentation.
Power factor meter transducer type ac features high torque to weight ratio. Analogue power factor meters lf analogue meters with moving iron movement. Moving iron instruments are meant for measuring ac current and voltage. Theory permanent magnet moving coil pmmc instruments. What is difference between moving iron and moving coil instruments. Analogue meters with moving iron movement application. Measurements and instrumentation miet engineering college. A dynamometer type power factor meter consists of two fixed coils ff connected in series carrying the load current or a definite fraction of it forming the current circuit, and two identical moving coils a and b fixed at the nearly right angle to each other pivoted on the same spindle forming the pressure circuit as shown in the figure. This instrument is one of the most primitive forms of measuring and relay instrument.
Moving iron type instruments are of mainly two types. All meters incorporate slidein dials and terminal covers as standard. Scales are 240 moving iron and 250 moving coil with parallax errorfree platform dials. Power factor meters electrodynamometer type power factor meter.
An older moving iron ammeter with its characteristic nonlinear scale and with the moving iron ammeter symbol mounted on a small form factor pc. Models 20 and 2014 are moving iron type instruments using a tautband suspension system. When a current carrying coil is placed in the magnetic field produced by permanent magnet, the coil experiences a force and moves. At that time the position of the pointer indicates the phase difference. The transducer measures the phase angle between an ac voltage and the corresponding ac current, converting the signal into a proportional dc current which is then fed to the moving coil instrument. In nalderlipman moving iron power factor meter, the. The pfq power factor meter measures cos phi with a moving coil movement and an electronic transducer. Working principal of moving iron type synchroscope. In nalderlipman moving iron power factor meter, the magnetic field produced. Moving coil instrument or generally referred as the darsonval meter or a permanent magnet moving coil pmmc meter is mostly used in direct current measurement. The moving iron meter was invented by austrian engineer friedrich drexler in 1884. Bimetallic movement with additional moving iron movement, for instantaneous.
Movingiron power factor meter construction working. Moving iron description moving iron meters are intended for rms value and their indications are h type frame sizemm. Hence moving iron instruments can be used for both a. The adjustment of position of shading bands, in an energy meter is done to provide a friction compensation b creep compensation c braking torque d none of the above ans. The range offers iron vane and moving coil ac and dc ammeters and voltmeters, elapsed time and frequency meters.
In this type of moving iron power factor meter, three fixed coils of are mechanically fixed in such a way when these three coils will be supplied from three different phases, there will be a rotating magnetic field in the space between the coils. Lag adjustment power factor adjustment quadrature adjustment inductive load. Explanation of errors in moving iron instruments errors in moving iron instruments. They are used as watt meters,varmeters and with some modification as power factor meters and frequency meters. Available in four case sizes with different inputs and scalings for no overload and 2 x or 6 x overload. Before answering your question let me explain the working principle of both moving coil and moving iron instruments that will give you a basic idea. Study the constructional details, working and calibration of an ammeter m oving coil and moving iron type 5. Transducer for measuring phase angle power factor analogue meters with moving iron movement. Moving coil for instruments moving iron for instruments bimetal instrument vibrating reeds instruments auxiliary power supply the accepted tolerance for nominal values of the auxiliary power supply is.
Movingiron meter definition is an instrument in which a vane or plunger of soft iron is moved by the magnetic field set up by a coil carrying the current to be measured called also ironvane meter. To measure power, power factor in a 1phase circuit, using wattmeter and power factor meter and. It is defined as the ratio of active or actual power used in the circuit measured in watts or kilowatts w or. Power factor meters 10 power factor meters determine if systems are running with inductive or capacitive load. The iron element consists of a moving vane attached to a pointer, and a fixed vane, surrounded by a coil. An ammeter from am pere meter is a measuring instrument used to measure the current in a circuit. The register is simply a means of registering revolutions, and by proper gearing is arranged to read directly in kilowatthours. Moving iron ac voltmeters available in four case sizes. By changing the meter scale calibration, the movement can be used to measure dc current and voltage. The basic construction of this instrument is shown in figure 2. Important measuring instruments multiple choice questions. In electrodynamometer type power factor meter there are further two types on the basis of supply voltage.
The pointer rests anywhere on the scale when meter is not connected in the circuit. Three similar current transformers connected to three different phases supply the current to the. Moving iron type synchroscope construction and working. Locations where the ambient temperature is outside the range of 0 to 40c locations where relative humidity is outside the range of 25 to 80% locations subject to vibrations or shock impact locations subject to rain, dripping water, or direct sunlight.
Analog meters power factor meters, electronictype 90 dial. Movingiron meter definition of movingiron meter by. Dynamometer type wattmeter electrical technology youtube. Power factor is the percentage of electricity that is being used to do useful work. Because pmmc darsonal only for dc measuring instrument where as moving iron can measure both ac and dc go through types of measuring instruments. Rotating field type power factor meter construction.
Jul 25, 2018 the basic construction of attraction type moving iron instrument is illustrated bellow a thin disc of soft iron is eccentrically pivoted in front of a coil. Sine or distorted waveforms of nominal input current and nominal input voltage. Power factor meter connection, circuit, wiring diagram. The basic construction of attraction type moving iron instrument is illustrated bellow a thin disc of soft iron is eccentrically pivoted in front of a coil. Moving iron instruments voltmeter and ammeter analog ammeter and voltmeter designed to measure a. The moving iron instruments or mi instruments are quite cheap in cost, simple in construction and very accurate at fixed power supply frequency. Electronic measurement power factor meter slideshare.
Insures rapid, accurate readings with high damping and minimum frictional effect. Bulletin 2074ae panel meters clearline series and fs,fl. It also deals with the measurement of rlc parameters voltage, current power factor, power, energy and magnetic measurements. The deflections in three phase power factor meters are independent of frequency and waveform since the currents in the two moving coils are affected in the same way by any change of frequency. The action of these instruments is based on the motoring principle. Induction type energy meter ii electrical technology ii unit 3 s. Electrical measurements pdf notes em pdf notes smartzworld. The magnetic field induces by the electromagnet whose strength depends. Thus whatever may be the direction of the current in the coil, the deflection in the moving iron instruments is in the same direction. Therefore the deflection of this iron piece is equal to the phase angle between the voltages and the currents of the threephase supply system. This type of meter responds to both direct and alternating currents as opposed to the moving coil ammeter, which works on direct current only. For watt, var and power factor meters dielectric strength between electrical circuit and the case. Thanks for reading about power factor meter working principle. A low value for the power factor means that much of the system capacity is not available for useful work.
In nalderlipman moving iron power factor meter, the magnetic field produced published on 10 nov 15. The movingcoil movement of the indicating instrument com prises a coretype magnetic system with twin spring loaded shock absorbing jewel bearings. Power factor meters electrodynamometer type power factor. Ac instruments are available with true rms converting circuit or rms compensated rectifier. From a utility viewpoint, this means reduced ability to deliver revenueproducing active power. What is the difference between movingiron and movingcoil. Difference between instrument and power transformers 49.
Power monitoring equipment fmpc 201009 pdf fols dec2009. Single phase electrodynamometer power factor meter duration. Electrical instruments and measure ments learning objectives absolute and secondary instruments deflecting torque controlling torque damping torque moving iron ammeters and voltmeters moving coil instruments permanent magnet type instruments voltmeter sensitivity electrodynamic or dynamometer type instruments hotwire instruments megger induction. For power measurement of three phase circuit by two wattmeter method, when the value of power factor is less than 0. Moving iron instruments page 45 moving coil instruments with rectifier page 49 volt ammeter with switch page 4 maximun demand indicators page 415 triple quadruple instruments page 417 power power factor meter page 421 phase sequence indicators page 428 frequency instruments page 429 synchronization instruments page 431. Mcq on measuring instruments 4 how engineering works. Portable needleindicator frequency meters 6 portable power factor meters 7 portable wattmeters 8 miniature portable ammeters and voltmeters 9 instrument transformers 10. At this condition, the moving iron type synchroscope behaves as a moving iron type power factor meter. Controlling torque brings the pointer back to zero when the deflecting torque is.
Nalderlipman moving iron power factor meter direction. Ac power factor meter ac power factor meter specifications ratings,selfcontained current windings 5a. Do not use yokogawa portable instruments in locations such as the following. Apr 11, 2015 electrical instruments and measurments 1.
Voltage windings minimum 50v, maximum 600v accuracy balanced load. In a low power factor wattmeter the pressure coil is connected a to the supply side of the current coil. Measurements and instrumentation questions and answers pdf free download for ece mcqs objective type interview questions lab viva manual gate cat syllabus. Moving iron power factor meters are the three phase power factor meters. Scales are 240 moving iron and 250 moving coil with parallax errorfree. Moving iron meter construction and working duration. Features and specifications ac and dc panel instruments. Power electronics and micro controller power electronics devices 4 converters, ac regulators, choppers, inverters and cycloconvertors 6 micro controllers 4 total 100 annexure iii model questions for electrical and electronics engineering 1. Now there are two types of power factor meters electrodynamometer type. Power factor meter incorporates two pressure coils one with noninductive resistance in. Scales are calibrated down to 20%, and ammeters can have overload scales x2, x3, x5 or x6 for motor start duty. Scales are calibrated down to 20%, and ammeters can have overload scales x2. Extension of range of wattmeter using instrument transformers. Suppose there is no difference in the frequency between the existing electrical system and the incoming generator.
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