We have an existing PIC18F258 microcontroller and need to add a high voltage voltmeter and ammeter inputs. We are looking for a company or individual to design the circuitry. The voltmeter must be able to accurately measure up to 400v. The ammeter must measure between 0 and 30 amps of current at 30 kHz AC, ideally through a current transformer (though we would be open to other methods so long as it is electrically isolated.)
Requirements
[login to view URL] voltage sensing circuitry must measure from 0 – 400 VDC
[login to view URL] voltage sensing circuitry must have an accuracy / resolution of no less than 350 mV across the entire voltage range.
[login to view URL] voltage sensing circuitry must maintain the accuracy across a temperature range of at least -40C to 80C
[login to view URL] voltage sensing circuitry must have a specified working temperature range of at least -40C to 80C
[login to view URL] voltage sensing circuitry must have a safety such that any single component failure will not lead to the PIC microcontroller being exposed to high voltage.
[login to view URL] ammeter circuitry must have a specified working temperature range of at least -40C to 80C
[login to view URL] ammeter circuitry must be compatible with AC at 30kHz (for use in an isolated full bridge SMPS.)
[login to view URL] ammeter circuitry must have an accuracy / resolution to measure within 250mA.
[login to view URL] circuits must be able to operate in a high noise environment.
What we expect:
1.)Schematics for voltmeter and ammeter circuits
2.)Part numbers and specs for all components including current transformer. (exception: we do not need part numbers for standard 5% resistors, only values)
3.)Sample microcontroller code in C/C++ for data acquisition routines including any necessary calculations (pseudo code is acceptable)
4.)We will own the rights to the circuitry
5.)The project must be completed within 10 days after the project is awarded.
Payment will be place in an escrow account and released when the project is finished.
Will need existing board schematic, if selected. As a designer of railway protection system we have good knowledge of component failure and temperature range accuracy.
I have designed 6 phase volt meter for 0-300V at 50Hz and ampMeter fot CT 3 phase and 1 chennel for ground neutral voltage measurement. Over under current and voltage protection is avaialble with realy opration. This board was designed for generator's voltage regulation project. So lets do this project togeather.