Page 303 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Fig 1 & 2

Digital Energy meters

Objectives: At the end of this lesson you shall be able to:
• describe the functional operation of digital type energymeter from block diagram.

Electronic (Digital energy meter)
This meters measure the energy using highly integrated components and it digitizs the instantaneous voltage and
current in a high-resolution sigma-delta analogue to digital converter (ADC), gives the instantaneous power in
watts. Integration over time gives energy used, measured in kilo-Watt hour. The block diagram for a digital meter
is shown in Fig 1. The two sensors, voltage and current sensors are employed.

Fig 1

The voltage sensor built around a step down element and potential divider network sensors both the phase
voltage and load voltage.
The second sensor is a current sensor, which senses the current drawn by the load at any point in time .

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CITS : Power - Electrician & Wireman - Lesson 50-53