Phase Chopping or Phase Cut Control

Hi Group!
Wondering if anyone can give a brief explanation of "phase cut" or "phase chopping" control. Just ran across this in a brochure for a Honeywell controller and haven't heard of it before.
TIA
Happy New Year to all!
Fred
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Spent a whole lot of time on Google there did ya Freddy? Bubba
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Hey Bubba!
As a matter of fact I did...couldn't find much of an explanation.
Want to recommend a good link?
wrote:

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Fred posted for all of us...

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Tekkie Don\'t bother to thank me, I do this as a public service.

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Hey Fred, No, but thanks for asking. I usually do my own homework. Try Yahoo, Msn, etc. Bubba

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O God run, bubba trying to answer electrical questions!
bubba is a dumb shit!
-Canadian Heat
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On 20 Jan 2007 21:47:22 GMT, DANgER ( snipped-for-privacy@heat.com) wrote:

Hey, whats up $100 Canadian trailer billy? Your not still molesting your daughters in there, are you? Bubba
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"Hey, whats up $100 Canadian trailer billy? - bubba"
Wow that insult has me speechless!
I have nothing to hide bubbs! post your pic and bank statements...I would love to compare lives. Let the forum vote, most pathetic has to leave... got balls bubbs? I have more money in my dirty laundry then you have in the bank old man!
That's what I thought!!! No balls bubbs!
-Canadian Heat
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Don't do it, Bubba! That Canuck money isn't worth much, and his large number of dollars will appear to be bigger than yours.
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On 20 Jan 2007 22:03:06 GMT, DANgER ( snipped-for-privacy@heat.com) wrote:

You need to be pinched and wake up. Its all a dream. And the only thing you have in your dirty laundry is shit streaks in your shorts. Try "Depends" you fat fuck. Bubba
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I suspect it is refering to an scr style speed control. You phase shift the signal a little and use it to drive the scr. The scr turns on partway through the sine wave. Src's turn them selves off when the sine wave passes 0. Then you signal it again part way through the next sine wave. The result is a partial sine wave that gives you a lower effective rms voltage because you have a longer period at 0 volts.

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Hey James!
Thanks for taking the time...now I'm more curious about this particular control scheme. I'm familiar with scr/triac control for regulating output power...to a lamp or fan motor for example...but haven't seen this used on 24VAC control circuits.
Are there controllers that use this phase cut/chopping scheme for control at 24V AC??
Fred

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I have not personally seen any but the principle is the same. The voltage doesn't matter as long as it is ac. In fact I suspect a regular 115 lamp dimmer would work on 24 volt.

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mechanism behind triggering the triac at the proper point of each AC cycle. The breakover voltage of the device is chosen based on the design voltage of the dimmer. At 24 volts, you might be lucky to get a very small range of functionality.
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How does the control vary the breakover point?

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Mo has a point there...most diacs in dimmer switches don't "break over" until the voltage reaches around 30V. Wouldn't work on a 24VAC circuit.
Fred

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