With the development of large scale integrated circuit and computer application technology, the kinds of the electronic instrument is becoming more and more large,and their functions are getting more and more stronger. The intelegent power instrument this thesis concerns is one of these electronic instruments.
The ADE7755 is a high accuracy electrical energy measurement IC. The part secifications surpass the accuracy requirements as quoted in the IEC1036 standard. See Analog Devices’ Application Note AN-559 for a description of an IEC1036 watt-hour meter reference design based on the AD7755.
The only analog circuitry used in the ADE7755 is in the ADCs and reference circuit. All other signal processing (e.g., multiplication and filtering) is carried out in the digital domain. This approach provides superior stability and accuracy over extremes in environmental conditions and over time.
The ADE7755 supplies average real power information on the low-frequency outputs F1 and F2. These logic outputs may be used to directly drive an electromechanical counter or interface to an MCU. The CF logic output gives instantaneous real power information. This output is intended to be used for calibration purposes or for interfacing to an MCU.
The intelegent power instrument makes the electrical energy measurement IC ADE7755 to give rise to a serial impulse proportional to the load’s instant active power.Then, It uses microcontroller unit AT89S51 to caculate the impulse and display the result, and give rise to all kinds of control singnal from the result and the keystroking.
Thus, The intelegent power instrument can realize on-line measurement to citizen users. It can implement on-line supervision to users’ using condition, which include overloaded runningsupervision, users’ stealing electricity supervision, tel-control, local electricity capacity’s overdraw control and so on. It also can realize asynchronous serial communications with the computer which connects with it to make up network to show the computer and network’s advantageous lightly and improve its intelegence.
Key words: Intelegent power instrument; Electrical energy measurement IC ADE7755;
Microcontroller unit AT89S51; on-line measurement; on-line supervision;
asynchronous serial communications
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