Electricity Metering

Energy Management Branch – WPN08th February 2013

Overview of Topics

1. Introduction to electricity metering

2. Classification of electricity meters based on technology

3. Working principles, metering concepts

4. Net metering & Forward metering

5. Metering errors and meter tampers

Overview of Topics cont’d

6. Meter Testing, Meter Test Benches and Equipment

7. Distribution loss reduction through metering

3. Working principles and metering concepts

1. Voltage Coil – High impedance element

2. Current Coil – Low Impedance element

3. Stator – Concentrate and confines magnetic

filed

4. Aluminium rotor disk

5. Brake magnet

6. Spindle with worm gear

7. Display registers

Principle of Operation

Ferraris meter construction

Voltage element

Current element

Rotor

Disc speed proportional to power

p = u . i

u

i

u

i

x x

v = u • i •k

Voltage element

Current element

Disc

Metering unit 2

Metering unit 1 Metering unit 3

Electronic/ Static meters

Smart meters – block diagram

Measurement parameters of meters

• Active energy, kWh, MWh

• Reactive energy, kVarh, MVarh

• Apparent Energy, kVah, Mvah

• Maximum demand

(15-minute average Apparent/ Active power)

Power Triangle -

1.2 Metering Terminology cont’d

Four Quadrant energy measurement

Q 1 - Active energy import, pf laggingQ 2 - Active energy export, pf laggingQ 3 - Active energy export, pf leadingQ 2 - Active energy import, pf leading