The basic blocks of the conditioning system for a dc energy meter are formed from a voltage divider for the voltage input, and a shunt for the current input. After these passive components, two preamplifiers are usually introduced before the processing system. The current preamplifier is very important because:

1. The voltage output level of the current shunt is very low, even at full scale.

2. Many times, the current input has to support overloaded signals; the presence of a variable gain amplifier allows acceptable working conditions for the system.

3. It can be used to implement an active filter before signal processing.

Voltage and Current Adapters for ac Electronic Energy Meters

The most common devices to process ac signals for static energy meters are the traditional voltage and current transformers. They must be made with proper components to achieve the right amplitude of the voltage inputs (by nonreactive shunts for the current transformers, and nonreactive voltage dividers for the voltage transformers). After the transformers, and related devices, a second block, based on electronic amplifiers, provides the final analog processing of the input signals, as for the dc conditioning systems.

It is useful to introduce this second processing element because analog filters are generally required when the input signals need to be digitally processed.

Mark the following statements as true or false

1. Modern electronic multipliers use resistors

2. The devices based on analog components are completely dynamic.

3. There are prototypes in the class of static energy meters.

4. Up-to-date digital instruments based on structures implementing DSPs.

5. Three preamplifiers are usually introduced before the processing system.

6. The current preamplifier is very important because it can be used to implement an active filter before signal processing.

7. The most common devices to process ac signals for static energy meters are the traditional voltage and current transformers.

Complete the sentences using information from the text.

1. In their first version, electronic multipliers used … .

2. Voltage and current signals are processed to obtain … .

3. The result is integrated over the observation time in order to … .

4. The first realizations were based on … .

5. Now, more sophisticated digital instruments are under design and development, based on … .

6. The basic blocks of the conditioning system for a dc energy meter are formed from … .

7. The current preamplifier is very important because … .

8. The most common devices to process ac signals for static energy meters are …

Use the pictures and description data to tell your partner about the following devices.

Single Phase Tamper-proof Static Energy Meter DESCRIPTION Major technical data: Accuracy class: 1.0 Power consumption: < 6VA Rated voltage: 220V Basic current: 1.5(6)A, 5(30)A, 10(50)A, 20(80)A Rated frequency: 50Hz Overload: 6 times Operating life: >20 years Main functions: used to measure the energy of 50Hz single phase A...C power. Features: 1) High accuracy, reliability, overload capability 2) Low power consumption 3) SMT technology and re-flow soldering technology 4) Light weight, small size, easy to install

1P2W Anti-Tamper Energy Meter   DESCRITION 1. Bi-directional active energy measurement 2. Reversed energy measurement 3. Unbalanced energy measurement 4. Mechanical counter display or LCD display 5. Pulse output with optical-coupling isolated 6. Adopt high quality & reliability components SPECIFCATION 1. Standard: Applicable IEC 61036-2000 2. Accuracy: Class1, Class2 3. Rate voltage: 110V, 220V +/- 20% 4. Rate current: 5(30)A, 10(60)A, 20(120)A 5. Frequency: 50Hz, 60Hz +/-10% 6. Power consumption: Voltage: ≤1W/4VA Current: ≤0.5VA 7. Operation TEMP: -25~+55º C 8. Storage TEMP: -40~+70º C

16. Write a short essay on the topic: “Means of energy measurement”.

Unit 15

VOLTAGE MEASUREMENT