§ 14 The principle of operation of the electronic meter A100
Design and operation of basic elements
Electronic counter module
The high measurement accuracy of the active energy is achieved by using a special measuring IC, including delta-sigma converters (ADC) for current and voltage input signals, with a highly stable reference voltage and a crystal oscillator, as well as a digital signal processor (DSP). The output signals of the two “delta-sigma” converters are fed to a digital signal processor (DSP), where they are processed and multiplied. As a result, at the output of the digital signal processor (DSP) pulses are formed with a frequency in proportion to the power consumed. Also, the digital signal processor controls the process of isolating and filtering the possible constant component of the current and voltage signals. The counting of pulses produced by the digital signal processor is performed by the microcontroller, followed by an increase in the register of the active tariff and the storage (recording) of data in the non-volatile EEPROM memory. The microcontroller is an important link between the microprocessor and the peripheral devices of the circuit, controlling the operation of the liquid crystal display (LCD), the LED indicator, the IrDA port, and the pulse output.
Calibration Constants Used for Calculations Required loaded into the meter at the factory and stored in non-volatile EEPROM memory along with configuration.
In the current circuit of the meter, a low-resistance shunt with resistance not more than 0.6 mΩ. Voltage before entering the delta-sigma input transducer passes through a series of highly linear resistive voltage dividers.
All main electronic elements of the counter are located on one PCB with planar-surface and end-to-end installation. On The circuit board has the following components:
measuring IC (measuring chip)
resistive voltage dividers
Delta-Sigma Current and Voltage Converters (ADC)
liquid crystal display (LCD)
crystal oscillator (megahertz range)
Fig. 1. Structural diagram of the counter type A100
In all versions of the A100 meters, a power source is installed, designed for a wide range of input voltage supply networks - from 184 to 276 V. For reliable protection against overloads and fast transient bursts input power supply circuits have non-linear suppression device, a series of protective current resistors and voltage, as well as the high pass filter.
Voltage measurement sensors
To obtain a highly linear voltage signal and minimize the phase shift in a wide dynamic range, resistive voltage dividers are used.
Highly stable SMT resistors with a minimum temperature coefficient are used as dividers.
The voltage is applied directly to the main board, where, using resistive dividers, they are brought to the required level of input signals for the “delta-sigma” converter of the measuring IC (ADC).
The measuring IC in the circuit provides an accurate measurement of voltage and current for use in calculating the required values.
Signal conversion and calculation
Measuring IC contains delta-sigma converters (ADC) which convert voltage and current input signals to digital code and digital signal processor (DSP) corresponding to multiply the results of the ADC. Further measuring IC converts energy into pulses for a microcontroller counter, which processes input pulses and transfers data to memory the counter, and also if necessary provides data transmission on LCD and peripheral devices of the circuit (relay, ports). Also The measurement IC contains a power interruption detection circuit. sending the corresponding signal to the microcontroller. Permanent calibrations stored in EEPROM memory are loaded into the counter at the factory and become part of the relevant operations calculating the necessary quantities.
The microcontroller performs various functions, such as:
receiving control signals tariff input
communication between DSP and EEPROM memory
data transmission via IrDA port
LED and pulse LED control output (S0)
liquid crystal display (LCD) operation control
Microcontroller and measuring IC constantly communicate among themselves for continuous processing of input signals of currents and stresses. When a power meter is detected, the microcontroller initiates shutdown and saves the calculated and other data.
A100 counters use non-volatile EEPROM memory
for long-term storage configuration, factory permanent
(constants), settlement (commercial) and other data.
power recovery (supply) all data is read from memory
the microcontroller and the meter returns to working condition before
In the absence of power, memory can maintain safety. data at least 10 years.
Liquid Crystal Indicator (LCD )
The liquid crystal indicator (LCD) is used for
display of measured (calculated) data and status
The displayed LCD segments have high contrast and easily distinguishable from different angles. LCDs can be divided into several information zones. (fields), each of which displays specific information, as shown in Figure 1-5.
Auxiliary (service) functions
Additional functionsAdditional (service) functions can be used for obtaining reference information on the reliability of work and accounting active electric energy meter A100. This data may be read on the PC via the IrDA port counter.
Below are given data giving information on reliable electricity metering.
Energy flow in the opposite direction
The number of cases of reverse energyCounter A100 detects and stores the total number in memory cases of energy flow in the opposite direction. Counter detects flow in the opposite direction only in case exceeding the set energy threshold (5Wh). Threshold value installed at the factory.
Total active energy released
Counter A100 detects and writes to memory the total
the value of the active energy released.
The indicator of the reverse flow of energy is displayed on the LCD in the case of
detection of current flow in the opposite direction (issue).
The indicator of the reverse flow of energy will remain on the LCD until the moment when the meter is turned off, even if the current is again flow forward (consumption).
The counter makes counting and registration in memory of each full hours of work (excluding time of power failure) and stores work duration over a period of 27 years.
Number of power outages
The counter makes counting and registration in memory of quantity power outages.
Idle current time
The time counter counts and registers each complete hours of the counter in the absence of current. This mode allows you to detect the wrong pattern of consumer load.
Control functionsInternal fault counter
This device records the number of CPU restarts due to emergency work (failure of the microprocessor to work properly).