8. INTEGRATING METERS (ENERGY METERS)
Integrating or energy meters are used to measure the quantity of electric energy supplied to a circuit in a given time. They give no direct indication of power i.e., as to the rate at which energy is being supplied because their registrations are independent of the rate at which at given quantity of electric energy being consumed.
The main difference between an energy meter and a wattmeter is that the former is fitted with some type of registration mechanism whereby all the instantaneous readings of power are summed over a definite period of time whereas the latter indicates the value at a particular instant where it is read.