Circuit help: switching a load only at peak of AC mains

J

JB

Guest
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle? I'll probably
use a substantial relay or thyristor to do the actual switching. This is for
a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.
JB
 
"JB"
I have a series of measurements to make of the inrush current of a range
of LED drivers and electronic ballasts. Is there a simple way of ensuring
that the load is always switched on at the peak of the mains cycle? I'll
probably use a substantial relay or thyristor to do the actual switching.
This is for a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.
Click to expand...

** Well, a zero crossing detector followed by a 5 m/S delay will do it.

I know someone with exactly the same task as yours and he used a PIC
programmed to get both zero and peak switching of a triac - which he also
bypassed with a hefty relay operated simultaneously to eliminate glitches
associated with some of the loads encountered.



.... Phil
 
"JB" <nil@spam.net> schreef in bericht news:l192ma$mrv$1@dont-email.me...
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle? I'll
probably use a substantial relay or thyristor to do the actual switching.
This is for a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.
JB
Click to expand...

Can it be that difficult to make a 90 degrees shifted sine and switch on the
zero crossing of it?

petrus bitbyter
 
petrus bitbyter wrote:
"JB" <nil@spam.net> schreef in bericht news:l192ma$mrv$1@dont-email.me...

I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle? I'll
probably use a substantial relay or thyristor to do the actual switching.
This is for a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.

Can it be that difficult to make a 90 degrees shifted sine and switch on the
zero crossing of it?
Click to expand...

Timing it is easy. But if it is part of a regulation scheme the thyristor
will also have be capable of being turned off while carrying full current.
What's the term for this - commutation?

Or is this a problem of designing a solid state relay that remains on for
one or more cycles, one where it is allowed for the thyristor to turn off
on its own at the next zero crossing following the arrival of the "off"
signal?

George

petrus bitbyter
Click to expand...
 
On 9/17/13 1:08 AM, JB wrote:
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle? I'll probably
use a substantial relay or thyristor to do the actual switching. This is for
a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.
JB
Click to expand...

Can you just give it the right voltage as a DC pulse to perform your
measurements? That seems like an easier task to me.
 
On 9/17/13 1:08 AM, JB wrote:
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle? I'll probably
use a substantial relay or thyristor to do the actual switching. This is for
a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.
JB
Click to expand...

Can you just give it the right voltage as a DC pulse to perform your
measurements? That seems like an easier task to me.
 
"Daniel is the Pitts"

Can you just give it the right voltage as a DC pulse to perform your
measurements? That seems like an easier task to me.
Click to expand...

** So stupid, it's actually funny.




.... Phil
 
"George Cornelius" <cornelius@encompasserve.org> schreef in bericht
news:5238bee2$0$63203$815e3792@news.qwest.net...
petrus bitbyter wrote:
"JB" <nil@spam.net> schreef in bericht news:l192ma$mrv$1@dont-email.me...

I have a series of measurements to make of the inrush current of a range
of
LED drivers and electronic ballasts. Is there a simple way of ensuring
that
the load is always switched on at the peak of the mains cycle? I'll
probably use a substantial relay or thyristor to do the actual switching.
This is for a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.

Can it be that difficult to make a 90 degrees shifted sine and switch on
the
zero crossing of it?

Timing it is easy. But if it is part of a regulation scheme the thyristor
will also have be capable of being turned off while carrying full current.
What's the term for this - commutation?

Or is this a problem of designing a solid state relay that remains on for
one or more cycles, one where it is allowed for the thyristor to turn off
on its own at the next zero crossing following the arrival of the "off"
signal?

George

petrus bitbyter
Click to expand...

The OP only asks for switching on so far. There are dozens of SSRs for sale
designed for switching on at zero crossing. So you use the shifted sine to
switch on the not-shifted. As for switching off GTO devices can be
considered. Common SSRs switch off at the zero crossing of the load current.

petrus bitbyter
 
"petrus bitbyter"
The OP only asks for switching on so far. There are dozens of SSRs for
sale designed for switching on at zero crossing. So you use the shifted
sine to switch on the not-shifted. As for switching off GTO devices can be
considered. Common SSRs switch off at the zero crossing of the load
current.
Click to expand...

** The loads being considered are essentially off line switchers (
PS ) - so the current draw falls to near zero just after each AC voltage
peak, requiring the SSR to be re-triggered every half cycle at the next
peak.

Or, just drive the LED on continually until you want the SSR it to
commutate off.



..... Phil
 
On 9/18/13 4:42 AM, Phil Allison wrote:
"Daniel is the Pitts"
Why don't you enlighten rather than belittle?


Can you just give it the right voltage as a DC pulse to perform your
measurements? That seems like an easier task to me.



** So stupid, it's actually funny.
You are? Well, I'll try not to laugh at you.
Click to expand...

On 9/17/13 1:08 AM, JB wrote:
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts.
Click to expand...

If the OP needs to make a measurement of the inrush current on the LED
drivers and ballasts, why not simulate the conditions the easiest way
possible?
 
On Tue, 17 Sep 2013 09:08:41 +0100, "JB" <nil@spam.net> wrote:

I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle? I'll probably
use a substantial relay or thyristor to do the actual switching. This is for
a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.
JB
Click to expand...

---
I see something with a push-button switch which enables a
zero-crossing detector which starts a 5 millisecond delay timer which
sets an R-S latch when it times out, which turns on a TRIAC at 90
degrees and holds it on until the R-S latch is reset by a push-button
switch.

Would that work for you?

BTW, cross-posting is better than multi-posting. :)

--
JF
--
JF
 
In article <l192ma$mrv$1@dont-email.me>, nil@spam.net says...
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle? I'll probably
use a substantial relay or thyristor to do the actual switching. This is for
a single phase 230V 50Hz supply.
I have done zero crossing triggers for switching loads but never peak! My
Google mojo seems to have deserted me on this one. Any help much
appreciated.
JB
Click to expand...

Zero Crossing detector
Measure Cycle Time
Divide by 2 (Shift Right)
Trigger Thyristor At that time
 
"Daniel Pitts" = "Daniel is the Pitts"
Why don't you enlighten rather than belittle?
Click to expand...

** No-one can teach a pig to sing.

And you are another PITA fucking troll.

Piss off.
 
On 9/18/13 5:45 PM, Phil Allison wrote:
"Daniel Pitts" = "Daniel is the Pitts"

Why don't you enlighten rather than belittle?



** No-one can teach a pig to sing.

And you are another PITA fucking troll.

Piss off.
Click to expand...

Lol, I think you were looking in a mirror and saw the troll.

*plonk*
 
"Daniel Pitts" = "Daniel is the Pitts"


** Fuck you - pig brain.



** No-one can teach a pig to sing.

And you are another PITA fucking troll.

Piss off.

Lol, I think you were looking in a mirror and saw the troll.

*plonk*
Click to expand...
 
On 2013-09-17, JB <nil@spam.net> wrote:
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle?
Click to expand...

use a dimmer and adjust it while observing?



--
⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
On 19 Sep 2013 08:15:55 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2013-09-17, JB <nil@spam.net> wrote:
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle?

use a dimmer and adjust it while observing?
Click to expand...

---
If he wants to switch the mains into a load at 90 degrees or 270
degrees and have the switch remain closed after that, then a dimmer
won't work.

--
JF
 
On Thu, 19 Sep 2013 04:13:48 -0500, John Fields
<jfields@austininstruments.com> Gave us:

On 19 Sep 2013 08:15:55 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2013-09-17, JB <nil@spam.net> wrote:
I have a series of measurements to make of the inrush current of a range of
LED drivers and electronic ballasts. Is there a simple way of ensuring that
the load is always switched on at the peak of the mains cycle?

use a dimmer and adjust it while observing?

---
If he wants to switch the mains into a load at 90 degrees or 270
degrees and have the switch remain closed after that, then a dimmer
won't work.
Click to expand...

I recently finished my 2 year "Last Great Desktop PC" build of what I
consider to be my last PC.

The gold series power supply was turned off at the hard switch, so I
could change a couple of SATA cable locations and add a drive.

When I turned the supply back on at the hard switch (still no PC rails
enabled) the only rail that is supposed to come up is the +5 volt
standby rail. But when I turned it on, I heard it audibly pop. I am
familiar with this sound, as I used to design and manufacture HV power
supplies in my recent past, and I knew that the switch was closed when
the AC line was at its peak. I thought 'That didn't sound good... I
hope everything is OK.'

Well, much to my dismay, the system would not start. I immediately
suspected the supply, and removing the main connector on the MOBO and
placing it on a PC Supply Tester thingy I bought a couple years ago and
it was showing one of the 12Volt rails down. So I set up an RMA with
the maker, and explain things, and they send me a new supply before I
even get them the old one back. Hooking the new supply up to the tester
shows the same problem. Then, I notice that I had not ALSO connected
the VGA connector to this tester. When I do that, both supplies show
good.

They want me to send it to them anyway, so I do, But I also state that
if the supply is OK that likely means that the problem is the mobo.
Sure enough, the new PS does not start the system, and the mobo still
shows the same error. So they RMA that item. They sent me the
replacement so I only need to put that back in.

Talk about a PITA though! Not the service they gave. just the
logistical facts of it all. I had to ship things from work. I had to
take apart a machine that started out working, and now I have to
re-assemble it again. I sure hope they did not somehow zap the CPU.
That alone was $600. That comes out to $100 for each core.
Their supply design should not do that though, and the pulse could only
have come down through the +5V standby rail as far as I can see.

The MOBO or the supply has some things which should have been
incorporated into their design to quell any such behavior. Power
supplies should not surge on the odd high line, high peak start
scenario. Anyway, they didn't clamp that inrush, apparently.
 
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