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Ttelmah
Joined: 11 Mar 2010 Posts: 19245
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Posted: Sun Jun 21, 2020 12:52 pm |
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No it isn't. The part number he quotes is not a ZCD part. |
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temtronic
Joined: 01 Jul 2010 Posts: 9125 Location: Greensville,Ontario
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Posted: Sun Jun 21, 2020 1:48 pm |
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Just throwing this out for thinking....
AC motor control is 'challenging' at the best of times and I'm wondering if there's an inherent problem with using both a ZCD sensor and a ZC SSR. Depending on the program there could be a signifigant time delay between the sensor seeing the ZC and the actuation of the ZC SSR.
Say the ZC sensor trips at the leading edge of the +ve going phase.....then some 'math'...THEN the ZC SSR won't fire until the -ve going edge of the sinewave.
Hopefully someone well versed in this can shed some light on whether I'm right or wrong or if it really matters .....
Jay |
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bkamen
Joined: 07 Jan 2004 Posts: 1611 Location: Central Illinois, USA
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Posted: Sun Jun 21, 2020 5:57 pm |
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Ttelmah wrote: |
No it isn't. The part number he quotes is not a ZCD part. |
I was saying from my project. (poorly worded)
I'll go back and word it better... _________________ Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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bkamen
Joined: 07 Jan 2004 Posts: 1611 Location: Central Illinois, USA
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Posted: Sun Jun 21, 2020 9:17 pm |
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temtronic wrote: | Just throwing this out for thinking....
AC motor control is 'challenging' at the best of times and I'm wondering if there's an inherent problem with using both a ZCD sensor and a ZC SSR. Depending on the program there could be a signifigant time delay between the sensor seeing the ZC and the actuation of the ZC SSR.
Say the ZC sensor trips at the leading edge of the +ve going phase.....then some 'math'...THEN the ZC SSR won't fire until the -ve going edge of the sinewave.
Hopefully someone well versed in this can shed some light on whether I'm right or wrong or if it really matters .....
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That's a valid question -- and I remember thinking/wondering about it too.
I designed that gizmo almost 10yrs ago. I'd have to go back and look at the details.
-Ben _________________ Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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Ttelmah
Joined: 11 Mar 2010 Posts: 19245
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Posted: Sun Jun 21, 2020 11:21 pm |
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Thanks Bkamen. It read as if you were saying his circuit was using
a ZCD SSD.
Fortunately, the inertia of motors 'helps' here.
You can switch off for three or four half cycles, and then on for just
one, and the motor merrily keeps swinging, but at a much reduced
speed. The big question is how quickly the motors slow, since this
affects how easy they are to genuinely speed control reasonably.
I've done controllers in the past allowing this type of motor to be
linearly controlled, but for this I synthesised the AC waveform using
MOSFET choppers, and could give a genuinely frequency controlled AC.
Unnecessarily complex for this application. |
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bkamen
Joined: 07 Jan 2004 Posts: 1611 Location: Central Illinois, USA
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Posted: Mon Jun 22, 2020 9:48 pm |
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Ttelmah wrote: | Thanks Bkamen. It read as if you were saying his circuit was using
a ZCD SSD.
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No problem.
And I need to go back and ultimately look at what I used --- as Jay mentions,
I may have originally opted for a ZCD SSR -- but not ended up needing/using one because of sync delay issues.
I'd have to go look -- but we've talked about it so the OP is aware. _________________ Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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