Phase Sequence Detector

One I designed for use in mainframes >25 years used resistors and opto- isolators in a "wye" configuration between the phases. The outputs of two of the photo-transistors then drive the 'D' and 'Ck' of a 74xx74 D- type flip-flip. Filter and buffer as appropriate.

Two lamps and a capacitor. And phasor diagrams! Most elegantly "Old School."

Oh that much else on the 'net was as well written.

--s falke

Could Someone inform, or point me to a site that describes the circuit or the operation of a Phase Sequence Detector? I need to create a tools that can detect phase sequense in 3 phase.... Pls , I need an idea....

Thank You....

Uda

| Two lamps and a capacitor. And phasor diagrams! Most elegantly "Old School." | | Oh that much else on the 'net was as well written. | | --s falke |

I agree.

I was very impressed after my mind had already started thinking about Zero crossing detectors and set / reset latches and such.

Makes me wonder if a design like this was planned from the start or discovered by accident.

Tom Grayson

True, But I think the "Two lamps and a capacitor" wins "hands down" on the grounds of simplicity and ease of construction.

but, to be fair, I have not seen the "Two lamps and a capacitor" work. I do know the little motor leaves absolutely no doubt :o)

Tom

But it sux if you have to do do anything other than light small and known lamps. Try it with LEDs.

Neither does a DFF, properly isolated and filtered.

Both work quite nicely: The motor type was produced commercially - looked like an oversized hockey puck with alittle window to view a rotating disc -probably was multipole and low torque so the disc movement could be seen as other tha a blur. The lamp/capacitor scheme also works nicely and is easy to build (and cheaper). I remember these from about 50 years ago.

-- Don Kelly snipped-for-privacy@peeshaw.ca remove the urine to answer

knoppinc.com/images/K3web.jpg

--s falke

Yup. That's the type I was thinking of. Cut one open one time (it had stopped working). Just a small set of coils on a small section of stator iron (just a small arc of the complete circle). Gave it the 'effect' of having multiple poles, just not a lot of torque (don't need it to spin the disk).

daestrom

It is still standard equipment for the utility meter guys around here. It also serves as a work light in a dark vault!

Ben Miller