Govt polytechnic college Amritsar. The movable part of a permanent-magnet instrument is displaced by the interaction between the magnetic field of the permanent magnet and the conductor carrying the current. Analog ammeters and voltmeters are classed together as there are no fundamental differences in their operating principles. The power loss in an ammeter is I 2R a where I is the current to be measured and R is the resistance of ammeter. The deflecting torque induces because of the movement of the coil. 
| Uploader: | Morr |
| Date Added: | 22 January 2006 |
| File Size: | 35.93 Mb |
| Operating Systems: | Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X |
| Downloads: | 60932 |
| Price: | Free* [*Free Regsitration Required] |
The pointer is made of the lightweight material, and hence it is easily deflected with the movement of the coil. Measurement of Energy Energy is measured by means of the energy meter watt-hour- meter Energy meter is an integrating. The power loss in an ammeter is I 2R a where I is the current to be measured and R is the resistance of ammeter. The deflecting torque is expressed by the equation shown instument. The coil is wound with the silk cover copper wire between the poles of a magnet.
Govt polytechnic college Amritsar.
Such instruments are sensitive to overloads and mechanical shock and impact but are relatively insensitive to the effect of external magnetic fields and ambient temperatures.
When a current flows through the windings of the frame, forces are generated that produce torque.
Permanent magnet moving iron type instruments - ppt download
Springs — The weakness of the spring increases the deflection of moving coil between the permanent magnet. Thus all analog voltmeters and ammeters are essentially current measuring devices. Download ppt "Permanent magnet moving iron type instruments". The swamping resistance reduces the inshrument of temperature on the moving coil.
One degree rise in temperature reduces the 0. Feedback Privacy Policy Feedback.
Permanent magnet moving iron type instruments
Errors due to friction is quite small as torque-weight ratio is high in moving-iron instruments. Leave a Reply Cancel reply Your email address will not be published. Two different designs are in common use. To make this website work, we log user data and share it with processors.
These instruments are more accurate ,east to use in every pmcm of measuring the quantity. The spring also provides the path to the lead current to flow in and out of the moving coil. Registration Forgot your password? The spring provides the restoring torque to the moving coil which is expressed as.
MOVING IRON |authorSTREAM
The pointer notices the deflection of the coil, and the magnitude of their deviation is shown on the scale. The action of all ammeters and voltmeters, with the exception of electrostatic type of instruments, depends upon a deflecting torque opt by an electric current.
Thus moving iron instruments are unpolarised instruments i.
So, even for the small value of current, the coil show large deflection. The error occurs because of the change of the coil resistance on the shunt resistance.
The spring gets weakened because of the effect of the temperature. Readings are shown by pointers or luminous indicators: The special shape of the moving-iron discs is for obtaining a scale of suitable form.
Moving Coil — The coil is the current carrying part of the instruments which is plt moved between the stationary field of the permanent magnet.
Circuit Globe All about Electrical and Electronics. Register for MasteringPhysics www. Permanent-magnet quotient meters are also used. This happens because the coil is made up of copper wire which has high shunt resistance and the shunt wire made up of Magnin has low resistance.
Comments
Post a Comment