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please give any idea/concept for wrong AC Phase Sequence detecting

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i am trying to detect wrong AC Phase Sequence.
please give any idea/concept for wrong AC Phase Sequence detecting.
those are as ,
if i connect RA0 R PHASE,RA1 B PHASE & RA2 Y PHASE .
if any bode by default connect any phase any port . whats concept for wrong AC Phase Sequence detecting..

Les Jones

Well-Known Member
Most Helpful Member
There are many phase sequence detecter design on the web using small neon bulbs or LEDs. But as you mention Ra0, RA1 and RA2 I suspect you mean how do you do it using a microcontroller. My first idea would be to make three peak detectors detecting the positive peak (You could also use the negative peak but it must be the same peak for the three phases.) of the three phases. Use one peak to start a timing sequence then log the time of the peak on the other two phases. You will then know the phase squence.


Jon Wilder

Active Member
Can also use zero cross detection as well. I suspect that's how many of them do it.
Trigger an interrupt on Phase A's Zero-Crossing.
Measure time to Phase B's Z.C. and to Phase C's Z.C.
If Phase B is first, you have one situation, if Phase C is first, you have the other


Active Member
The simplest way I can think of is to square up the signals into pulses, and use phase A to set an SR flipflop to enable the phase B input and use phase C to reset the flipflop to disable the phase B input. If you see a pulse at the phase B input then you know that the rotation is ABC. Otherwise it's ACB.
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