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feasibility of a power meter with bs2p — Parallax Forums

feasibility of a power meter with bs2p

erp1976erp1976 Posts: 3
edited 2007-09-29 14:51 in BASIC Stamp
Im brand new to basic stamp·and looking for some advice. I have a project for school·where I have·chosen to build a power meter using the bs2p. My idea is to be able to display rms voltage current,·Pavg, S, and pf. I plan to use ADC to bring in voltage and current. I will use the Bs2p to find peak voltage, current.I will find Pavg by multiplying the instantaneous v and I and dividing by time. The freq is 60Hz. Is the Bsp2 capable of doing this? Is there too much of a delay and is it fast enough for what I want to do? Any comments or ideas on the implementation would be appreciated.······ thanks.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-09-29 01:01
    In terms of the raw processing, the BS2p should be fine.· The main problem is that of sampling both voltage and current at the same time.· If you use some kind of sample and hold circuitry, you can have the Stamp trigger both at the same time, then digitize the voltage and current at your leasure, probably using two channels of a multichannel ADC.· If you want to sample at a 60Hz rate, that gives you about 16ms per sample which should be enough time to do the calculations.· Sending the data to a display may be a problem though.· At 9600 Baud, that's only 16 characters per display cycle.· You could get around this by only updating a portion of the display per sample time.



    Post Edited (Mike Green) : 9/29/2007 1:07:40 AM GMT
  • FranklinFranklin Posts: 4,747
    edited 2007-09-29 01:40
    by clicking the icon in the upper right of your other post (red X) you can delete the duplicate post.

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    - Stephen
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2007-09-29 06:23
    The Cirrus CS5451A ADC chip may be worth a look. It's designed for power measurement and includes three each fully-differential voltage and current input channels that are synchronously-sampled. It has a serial interface and should play nice with the BASIC Stamp. It's designed for three-phase power systems, so may be a little overkill; but you don't have ot use all the inputs.

    -Phil
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2007-09-29 14:51
    Peak current and Peak voltage coincide only in purely resistive circuits.
    Oh, yes, it's the wonderful world of E-L-I &·I-C-E: P-F-C.

    http://en.wikipedia.org/wiki/Power_factor
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