What types of errors are occurred at Electrodynamometer wattmeter?
What types of errors are occurred at Electrodynamometer wattmeter?
Errors in Dynamometer Type Wattmeter :
- Errors Due to Mutual Inductance :
- Errors Due to Connections :
- Eddy Current Errors :
- Errors Due to Stray Magnetic Fields :
- Errors Due to Vibration of Moving System :
- Temperature Error :
- Errors Due to Voltage Coil Inductance :
- Errors Due to Voltage Coil Capacitance :
What is Electrodynamometer type instrument?
The electrodynamometer is a transfer-type instrument. An electrodynamic instrument is a moving-coil instrument in which the operating field is produced, not by a permanent magnet but by another fixed coil. This instrument can be used either as an ammeter or a voltmeter but is generally used as a wattmeter.
What are the merits and demerits of dynamometer type wattmeter?
Electrical Engineering ⇒ Topic : Advantages and Disadvantages of Dynamometer Type
- These types of instruments can be used for both DC as well as ac currents.
- Since iron is absent in the working parts of the instruments, these instruments are free.
- from hysteresis and eddy current errors.
Why Electrodynamometer instruments are known as transfer instruments?
These instruments have the same accuracy for both dc and ac. Explanation: Precision type electrodynamometer (EMMC) is used in the standardization process of the potentiometer and hence It is a transfer instrument.
What are the possible errors in energy meter?
The causes for error-wiring of three-phase three-wire electric energy metering device may include: the connection error between transformer and electric energy meter, the error of current transformer polarity and the error of voltage transformer polarity.
Which is not the cause of error in the wattmeter?
Wattmeter reading is not affected by temperature. Explanation: Wattmeter reading is affected by change in temperature. Resistance of the pressure coil and the spring stiffness are affected by the changes in temperature.
What is the working principle of Electrodynamometer?
The Electrodynamometer wattmeter working principle is very simple and easy. It is based on the theory of a current-carrying conductor experiences a magnetic force when it is placed in a magnetic field. The moving coil carries the current directly proportional to the voltage and connected across the voltage.
Why do we use Electrodynamometer?
An instrument in which the magnetic forces between two parts of the same circuit are used for detecting or measuring an electric current. An instrument, having a fixed and a moveable coil, that measures the power flowing in an electric circuit; a type of wattmeter.
What are the disadvantages of dynamometer type wattmeter?
Disadvantages of Dynamometer Type Wattmeter
- At low power factors, the inductance of the potential coil causes serious errors.
- The reading of the instrument may be affected by stray fields acting on the moving coil. To prevent it, magnetic shielding is provided by enclosing the instrument in an iron case.
What is the disadvantage of induction type wattmeter?
Disadvantages of Induction meter Without proper compensation measures, a considerable amount of errors are caused in the measurement due to temperature, waveform and frequency changes. Induction meters can use only for AC measurements. They consume a considerable amount of power. They have nonlinear scales.
Why the sensitivity of an Electrodynamometer instrument is low?
These instruments have a low torque/weight ratio and hence the low sensitivity. Low torque/weight ratio gives increased frictional losses. These errors must be minimized, if high accuracy is desired.
What is creeping error?
Whenever there is a current passing through the current coil with the coil excited, the disc of the energy meter rotates and measures the amount of energy consumed. The phenomenon of rotation of disc without any current through the current coil is known as Creeping. Due to this, the meter shows the incorrect reading.
What are the common errors in the electrodynamometer?
5.Stray Magnetic field Errors. The electrodynamometer type wattmeters has a weak operating field and therefore it effected by stray magnetic fields it will resulting in serious errors. Hence these instruments should be shielded against stray magnetic field. 6.Errors caused by vibration of moving system.
What are the applications of electrodynamometer?
Electrodynamometer instruments are capable of serving as transfer instruments. Indeed, their principal use as ammeters and voltmeters in laboratory and measurement work and as standards for calibration of other instruments as their accuracy is very high.
How do you reverse the electric field in an electrodynamometer?
In electrodynamometer instruments the field can be made to reverse simultaneously with the current in the movable coil if the field (fixed) coil is connected in series with the movable coil. The field is produced by a fixed coil.
What is the difference between transfer instruments and electrodynamic instruments?
This requires the transfer type instruments to have the same accuracy for both DC and AC. These instruments are also called Electrodynamic or Dynamometer Type Instruments. An electrodynamic instrument is a moving-coil instrument in which the operating field is produced, not by a permanent magnet but by another fixed coil.
