Absolute Instruments

Definition:
Absolute instruments are defined as the instruments that give deflections in terms of physical constants and not measurable on a graduated scale.

• The value of the electrical quantity to be measured are given by these instruments.
• The quantity are measured in terms of constants and from the deflection of the instruments only.
• Tangent galvanometer, Reyleigh current balance and absolute electrometer are some of the examples of absolute instruments.

These are specially costructed highly accurate instruments and they give the vlue of the electrical quantity to be measured in terms of their dimensions and the measured effect produced.They require no comparison with other instruments and thus no calibration is necessary. Their Operation and Maintenance require highly specialised knowledge and, therefore, they could only be used in the Standard Laboratories of different Countries of The World.

One Example of an absolute instrument is the Rayleigh Current Balance which is used for  absolute measurement of Current.

Read more:

1. Definitions Used in Electrical Measuring Instruments
2. Absolute Instruments
3. Secondary Instruments
4. Integrating Instruments
5. Recording Instruments
6. Indicating Instruments