I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

wrote in message
...
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.

On Thu, 26 Nov 2015 10:45:22 -0500, "Ralph Mowery"
wrote:


wrote in message
.. .
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.


Tektronix P6019 with the attenuator accessory

On Thursday, November 26, 2015 at 10:02:52 AM UTC-6, wrote:
On Thu, 26 Nov 2015 10:45:22 -0500, "Ralph Mowery"
wrote:


wrote in message
.. .
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.


Tektronix P6019 with the attenuator accessory

How much of a techie/geek can you be...with an AOL account? 💤

Ralph Mowery wrote:
wrote in message
...
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

What is the time division on the display? relay reaction time is in the
msecs. It is safe to say that loads have inductive reactance value
causing the spike like that.

I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.

On Thu, 26 Nov 2015 08:06:35 -0800 (PST)
bob_villain wrote:

On Thursday, November 26, 2015 at 10:02:52 AM UTC-6,
wrote:
On Thu, 26 Nov 2015 10:45:22 -0500, "Ralph Mowery"
wrote:


wrote in message
.. .
I put a 75w equivalent CFL on a scope with a current probe,
looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it
is not that simple. I assume this is also a very reactive load
so if you opened a relay at or near peak, it could get pretty
ugly

I have the B version of that scope. What are you using for the
current probe ? I may want to look into getting one.


Tektronix P6019 with the attenuator accessory

How much of a techie/geek can you be...with an AOL account? 💤

Better than anyone with a Gmail account...Damn Man!

On 11/25/2015 11:51 PM, wrote:
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

I suspect they are roughly coincident with the peak (slightly leading)
of the voltage waveform. So, apparent power is much higher (2A @ ~80+V?)

The problem with relay drives is you can't readily predict how
long it will take for the contacts to open. So, you can't
realistically try to open it near a zero crossing (or, ANYWHERE
that is "away from" the peak of the cycle and the peak current
draw/power consumption).

Likewise, unless it's a Hg-wetted relay, you can't tell how long
the contacts will *bounce* when making.

And, of course, if you're making consumer kit, you're usually quick
to trade off *any* sorts of real "specifications" for a few
micropennies!

Do you have access to a DSO? If so, you might try catching the
turn-on transient to see what a discharged primary cap looks
like to the line!

On 11/26/2015 8:45 AM, Ralph Mowery wrote:
wrote in message
...
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.

That was a great 'scope! I lugged one around the country at my first
job. Wouldn't enjoy doing that nowadays, though! :

Presently using a rescued TDS754D -- for the few occasions when I actually
need a 'scope.

On 11/26/2015 9:18 AM, Tony Hwang wrote:
Ralph Mowery wrote:
wrote in message
...
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

What is the time division on the display?

Should be pretty obvious -- current repeats with a periodicity that
tracks (rectified) line frequency. So, 8.3ms between repetitions...

relay reaction time is in the msecs.

You're not concerned with the actuation/release time (except if you
try to synchronize it with a certain point on the waveform (e.g., to
deliberately avoid these spikes which are roughly coincident with voltage
peak). You're more concerned with how long the contacts bounce
as they make/break -- especially when opening the connection
(cuz current is flowing and will want to maintain an arc across the
widening gap -- contacts melt)

It is safe to say that loads have inductive reactance value causing the spike
like that.

I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.

On Thu, 26 Nov 2015 08:06:35 -0800 (PST), bob_villain
wrote:

On Thursday, November 26, 2015 at 10:02:52 AM UTC-6, wrote:
On Thu, 26 Nov 2015 10:45:22 -0500, "Ralph Mowery"
wrote:


wrote in message
.. .
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.


Tektronix P6019 with the attenuator accessory

How much of a techie/geek can you be...with an AOL account? ?

I have had it since AOL started, long before anyone even knew what the
internet was. (Prodigy before that)
Right now I like it for my public Email address because I run AOL7 and
those nasty script based attacks simply pop up a gray error box.

On Thu, 26 Nov 2015 09:18:05 -0700, Tony Hwang
wrote:

What is the time division on the display? relay reaction time is in the
msecs. It is safe to say that loads have inductive reactance value
causing the spike like that.

That is just looking at the input capacitor(s) charging.
The signal is 60hz and I knocked it out of calibration to get the best
photo.

wrote in message
...
I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.


Tektronix P6019 with the attenuator accessory

I looked on ebay and they are around $ 200 used. I doubt that I will get
one, Just don't think I would use one enough to justify the price. I will
keep an eye out for one at fleamarkets.

On Thu, 26 Nov 2015 10:06:12 -0700, Don Y
wrote:

On 11/25/2015 11:51 PM, wrote:
I put a 75w equivalent CFL on a scope with a current probe, looking at
the wave form.
This is what it looks like

http://gfretwell.com/electrical/CFL%...0a%20scope.jpg

Those spikes are almost 2 amps so this might average 33w but it is not
that simple. I assume this is also a very reactive load so if you
opened a relay at or near peak, it could get pretty ugly

I suspect they are roughly coincident with the peak (slightly leading)
of the voltage waveform. So, apparent power is much higher (2A @ ~80+V?)

The problem with relay drives is you can't readily predict how
long it will take for the contacts to open. So, you can't
realistically try to open it near a zero crossing (or, ANYWHERE
that is "away from" the peak of the cycle and the peak current
draw/power consumption).

Likewise, unless it's a Hg-wetted relay, you can't tell how long
the contacts will *bounce* when making.

And, of course, if you're making consumer kit, you're usually quick
to trade off *any* sorts of real "specifications" for a few
micropennies!

"field engineering" would say use a big honking relay rated for DC.


Do you have access to a DSO? If so, you might try catching the
turn-on transient to see what a discharged primary cap looks
like to the line!

I might be able to catch it with the mask and an open shutter. I am
just not sure I care that much

On 11/26/2015 11:33 AM, wrote:

Do you have access to a DSO? If so, you might try catching the
turn-on transient to see what a discharged primary cap looks
like to the line!

I might be able to catch it with the mask and an open shutter. I am
just not sure I care that much

I suspect you can turn up generic waveforms someplace on-line
and extrapolate for your particular "load".

On Thu, 26 Nov 2015 13:29:38 -0500, "Ralph Mowery"
wrote:


wrote in message
.. .
I have the B version of that scope. What are you using for the current
probe ? I may want to look into getting one.


Tektronix P6019 with the attenuator accessory

I looked on ebay and they are around $ 200 used. I doubt that I will get
one, Just don't think I would use one enough to justify the price. I will
keep an eye out for one at fleamarkets.


I have a clamp on accessory for my Fluke meter that works as well but
you can't really trust the calibration as much, although the scope has
not been calibrated since the Clinton administration. It used to be on
a regular schedule when we were ISO 2000/1.
I got it as a present when I retired, along with my 453 Tek and a
bunch of other test equipment that nobody who stayed, knew how to use.
One of my favorites is the Dranitz 626 line monitor. You don't need it
much but when you do, there is not much else that will work.