Electrical Engineering ⇒ Topic : Instrument Efficiency

INSTRUMENT EFFICIENCY

It is defined as the ratio of the quantity to be measured at full scale to the power consumed by the instrument at full scale.

Let us consider an ammeter with the resistance R and I be the full scale reading.

Therefore, voltage at full scale reading is given by

                          V = IR                                                  .............. (1)

Hence, power at full scale reading is:

                          P = VI = I²R                                        ................ (2)

Thus, the efficiency η of the instrument is expressed as:

                          ................  (3)