ESR Meters

Status
Not open for further replies.
76nemo

76nemo

Senior Member
Location
Ogdensburg, NY
No hits so far. I have been pressing for a combination meter that could display ESR readouts and lissajous figures for quite some time. That would be invalueable to maintenance electricians. Guess I am a lone puppy dog:cool:
 
Last edited:
76nemo said:
--- combination meter that could display ESR readouts and lissajous figures for quite some time. That would be invalueable to maintenance electricians. ----
Click to expand...
As I recall from high school amateur radio stuff ('60s), "Lissajous" refers to the pattern one gets on an o'scope when one ac signal is applied to the x input and a different ac signal is applied to the y input. Interesting phenomenea, but I have no concept of how it could be used in a maintenance electrician setting. What would you use this for?

cf
 
Cold Fusion said:
As I recall from high school amateur radio stuff ('60s), "Lissajous" refers to the pattern one gets on an o'scope when one ac signal is applied to the x input and a different ac signal is applied to the y input. Interesting phenomenea, but I have no concept of how it could be used in a maintenance electrician setting. What would you use this for?

cf
Click to expand...

I wondered that too and I commented on it either in an earlier post or on another thread. I'm too indolent find which it was....
 
ESR= Equivalent series resistance. In my eyes, thee only real way to test the integrity of a cap.

Using lissajous figures is like using a megger in a PM program. They can show you forms of any circuit with different draws, but you'd have to know what you were looking at prior to performing the test. Now, on thee other hand, if you had a KGU to compare the unit against, lissajous figures are priceless. Lissajous figures are useless to a service guy walking in blind, but as far as plant maintenance, and a good PM program, show me a meter with the two features combined, and send me an invoice.

Not too many people utilize ESR meters, or even have any need for a tester capable of lissajous readouts. BUTTTTTTT,...... if you know how to use them properly, they are worth every dollar;) Fluke use to have the 867B, it had the "Component Test" function. That's what that function served, was graphing lissajous figures. They did away with it. Too bad, I say. I ended making my own in a 4x6" box to hook to my scope. Well worth it for $50.


As some have no idea of what exactly a "megger" shows, much, much less have any idea of lissajous figures and how useful they can be.
 
Besoeker said:
I wondered that too and I commented on it either in an earlier post or on another thread. I'm too indolent find which it was....
Click to expand...


Utilizing a test of that sort is not solely for checking individual components. A "curve tracer" as I call them, can load any individual circuit to find overall comparisons in any good PM program. Again, lissajous readouts are useless to any service guy walking in blind, and as I stated, so isn't megger readings on equipment you have no prior knowledge of.
 
Suggestion to moderators:
Maybe post 104 to 111 should be broken out into a separate thread on ESR meters

76 -
Okay, I now know what an ESR meter is. As I recall (from 45 years ago) these operate at 50MHz and a few tens of milivolts, generally used for checking DC power supply caps. The ones I remember had a 50microamp meter movement.

I've never heard of anyone using this type of device for checking high amperage power factor correction caps. Is this a common testing technique in the power industry (not the electronics biz)?

cf
 
Well, you can buy a Huntron for $3500: http://www.huntron.com/products/2800.htm


Orrrrrr, build your own if you already have a scope for $50,... you choose:grin:

curvetracer002.jpg


curvetracer004.jpg
 
090802-0818 EST

76nemo:

Lissajous curve.

www.wikipedia.org/wiki/Lissajous_curve

If you use sine wave excitation to a linear passive RC load and plot the applied voltage on one axis of an oscilloscope and the current on the other axis, then you will get a straight line when the two signals are in phase, a circle with 90 deg phase shift of one signal relative to the other, and an ellipse that varies in proportion to an intermediate phase shift.

Lissajous plots can be used to measure the integer relationship of the frequencies of two sine waves. Some examples are shown in the above reference.

.
 
090802-0932 EST

76nemo:

If you have a perfect capacitor the result is a circle. The difference between a slightly non-perfect circle and a perfect circle is hard to distinguish. A bridge type or other gage may be much better to evaluate a capacitor compared to a Lissajous curve.

A phase sensitive current meter that could extract the in phase component of the current relative to the voltage might provide good sensitivity for small loss values.

A Q meter is a device that has been used for years to measure RF losses. Many years ago I used one of these to evaluate different insulators for automotive antennas. Polydichlorstyrene was one of the better materials. Polystyrene is a very good insulator and capacitor material, but is poor temperature wise. The addition of chlorine improved its temperature capability. That was back in the days when there was still a tuned RF stage in the receiver to reduce image signals.

.
 
gar said:
090802-0932 EST

If you have a perfect capacitor the result is a circle. The difference between a slightly non-perfect circle and a perfect circle is hard to distinguish.
Click to expand...
I'm inclined to agree. And, if you have a less than prefectly sinusoudal supply (usually the case) that throws in other curved ball.

gar;1084025A said:
bridge type or other gage may be much better to evaluate a capacitor compared to a Lissajous curve.

A phase sensitive current meter that could extract the in phase component of the current relative to the voltage might provide good sensitivity for small loss values.
Click to expand...
If I had a concern about the imminent demise of a capacitor I'd first look at the case for signs of deformation. If none, I'd probably just measure its temperature and the current it is taking. If any of these three indications didn't look right, I'd replace it.
If I really wanted to know actual losses, I'd record current and voltage on a digital 'scope, drop the results into a spread sheet, and turn the handle to see what comes out. Even tan delta.
 
I shouldn't of put a a lissajous response into an ESR discussion. I made my own decade box for lissajous readouts. Lissajous figures are solely represented by current. Alot of guys I work with have never uesd a curve tracer. I still say they are invalueable to anyone referencing a KGU. I have had good response with ESR meters testing start/run caps.
I use these two test methods, and they have been like unfound gold when other methods only found dead fish.

I still find it odd that no one utilizes ESR meters or curve tracers. I like them alot, and would have them the first to be put on my bench. Maybe it's just me, and to each their own, but I find them priceless and extremely efficient when others are flipping through pages of schematics and I nail it down on a few test points.

Again gar/Besoeker, maybe it's just me, but I really like and rely on those two tests. Not many here work on board level, most get outsourced. For those of us that troubleshoot fixtures in-house, those tests alone are priceless.


Maybe it's me. I like different tests out of the box. When it comes to offline testing, lissajous figures are as good as it gets in my eyes.
 
090804-1837 EST

76nemo:

Please explain what these mean ----

1.
I made my own decade box for lissajous readouts.
Click to expand...
Decade box of what, and how is it used?

2.
Lissajous figures are solely represented by current.
Click to expand...
Explain meaning.

3.
A lot of guys I work with have never uesd a curve tracer. I still say they are invalueable to anyone referencing a KGU.
Click to expand...
A curve tracer of what? What is a KGU?

4.
What is the theory of your ESR meter?

.
 
Status
Not open for further replies.
Top