2nd Harmonic Grade test module

I need some help identifying something I bought at an auction. In with a bunch of older Modicon PLC modules, I found four new modules that are
made for a rack and "2nd Harmonic Grade" is printed on the front. There is a 10vDC meter, on/off switch, "ACPT" LED, "REJ" LED, J1 jack, J2 jack, gnd jack, and a Knobpot Bourns "Level" adjustment knob with an adjustable clock type setting under the top of the knob. The circuit board is marked with the number 0039-8416-9-006-01. This did not come up as a NSN. However, this is at least 15 years old so it could be obsolete. The circuit board has a logo that looks like a backward "K" joined to a lower case "b". Other than the electronic component labels, there are no other markings or name brands. It has 22 wide contacts in back of which 17 are in use. The contacts are side by side on a part of the circuit board for a blade (? term) contact. Here is a link to some pictures of this module. http://www.ardnet.com/3sands/2ndHarmonic.htm
I am not trying to sell them here, but I would like to know enough about this to put it on eBay for a little extra Christmas money. I have found out what the 2nd harmonic is and I am guessing that this will test certain electric or electronic devices. I don't know what it is called or what it tests. Any info will be greatly appreciated. A website for the product would make me your friend forever. Thanks in advance for any info you can provide. John Sands snipped-for-privacy@ardnet.com
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
john wrote:

Is there a company name? can you put up a picture somewhere. (alt.binaries or picture-hosting web sites.)
Jerry
--
Engineering is the art of making what you want from things you can get.

  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I couldn't find a brand name.
http://www.ardnet.com/3sands/images/Face.jpg is a photo of the pace plate and http://www.ardnet.com/3sands/2ndHarmonic.htm has three photos. John
Jerry Avins wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
john wrote:

I can't see the circuit board distinctly, but sometimes there's a name etched into it. This appears to be low-volume production, probably from a custom instrument.
Jerry
--
Engineering is the art of making what you want from things you can get.

  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
proclaimed to the world:

From what I saw, I would guess this is a one-off board someone made for testing the second harmonic levels in a transformer manufacturing facility. I saw two plugs, a go/no go indicator, a trip setting (pot) and a meter. When transformers are designed, the geometry dictates what the ratio of primary to secondary inrush current will be. Any defects in the windings can be detected by checking this ratio, so I would guess this was part of test station for this. I can also think of some other possible applications that would required something similar.
But to answer the question, this card is most likely a one of a kind and will not add to the value of the PLC he wants to sell.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Paul M wrote:

I like your analysis of the card's purpose, but I'm left with a niggling doubt. Third harmonic currents are much more prominent in transformers driven by low-impedance sine sources unless there's a DC bias to upset symmetry.
Jerry
--
Engineering is the art of making what you want from things you can get.

  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
proclaimed to the world:

This puzzled me too. I did a search to see what came up with second. Relay testing. Lots of stuff up in the radio bands. Switching power supplies produce 3rd and 5th harmonics. I also thought of motors. I have to think it is for some sort of winding test at least.
One of the things I ran across in my work that comes to mind is a motor winding tester consisting of a scope and power supply set to inject current into each winding (3P) and compare the ring voltages for each winding against each other. The waveform should be a degrading sine wave. Neat device for it's time called a surge tester. A motor rebuild shop would also use it to look for lamination problems. The pulse would induce HV across any air gaps that you could see in a dark room. I used to do a good business making custom testing setups for people. I found this to be one of the more rewarding parts of my business. My health continues to improve and thinking about this has re interested me in building that business up again. Sensor technology has improved so much since I have been out of it. There should be lots of opportunities. Always the capitalist.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.