Trivector meter is an energy meter which accurately measures all the parameters of supply such as voltage, current, power factor, active load, reactive load, apparent load etc., now a days static electronic meters are used for commercial and industrial applications. These electronic meters use micro controllers with their own programming language.
Trivector meter gets the input supply to be measured using CT/PTs. That is current input from Current Transformers and voltage input from Potential Transformers connected in the circuit. It is a true four quadrant measuring instrument. LCD display with annunciators for showing various critical events is used.
The following Measurement Values can be obtained using Trivector meter.
- Active Energy in MWh
- Reactive Energy in MVArh
- Apparent Energy in MVAh
- Maximum Demand in MVA
- Voltages of all the phases
- Currents of all the phases
- Power factor of all the phases
Principle of Operation:
The principle of operation of trivector energy meter is explained with the help of block diagram.
It mainly consists of the following units.
- Energy measuring unit: voltage sampling, current sampling, measuring integrated circuit
An analogue to digital converter is used to sample voltage and current relative to incoming waveform. For getting accurate results the sampling rate should be high.
- Data processing unit: Micro Controller Unit [MCU], Memory storage cards
Very highly reliable Read Only Memory [ROM] is used to retain the data for so many years even if there is no power.
- Power supply unit: AC power supply, battery
- Input/output unit: LCD display, Optical communication, RJ11 port for Remote communication
Data from ROM can either be displayed on the meter LCD or communicated via an optical communication port/RJ11 port on to a hand-held Meter Reading Instrument [MRI].
Major Components of Trivector Meter:
1. Energy Registers:
These are used for measuring Active, Reactive, and Apparent energy. These can be configured according to user’s requirement.
2. Maximum Demand Registers:
Maximum Demand is indicated for a particular time period. The demand is monitored during each demand interval and the maximum value of these demands is stored in the Maximum Demand register.
Whenever MD is reset, the registered MD value gets stored along with date and time of its occurrence.
3. LCD Display:
LCD display is used to show Reading Value indicators, Energy Unit indicators, Phase status indicators, Energy direction indication import or export, and Load status indicators Inductive or Capacitive as shown in the Block diagram.
4. TOD Registers:
These are used to support Time-of-Day metering, means to divide a day into certain time slots with tariff rates arranged in such a way so as to encourage consumers to reduce consumption during high demand hours and shift it to lower demand.
5. Data Communication:
- Local Communication:
Optical port is used to establish communication between meter and Meter Reading Instrument (MRI).
- Remote Communication:
RJ11 port is used to establish communication between meter and a compatible modem which uses Base Computer Software (BCS).
The connection diagram for 3-phase 4 wire meter is as shown in figure below.