Square D Watt Transducer Model No. CLE-204002

I swiped this from...

http://www.controlrepair.com/p5461_square-d-cle-208003-043s-combined-watt-var-transducer.html

All you need is a couple of properly sized PTs (Potential Transformers) and CTs (Current Transformers) and two properly calibrated meters and you're all set.

Oops, here's the picture...

RAMConsult, thanks for the help. I am hoping for a circuit schematic of the internals.

Hard to say what's inside the box, there's a number of different ways to electronically calculate Watts and VARs from those inputs. If you're trying to reverse engineer the box you'll find Google is your friend.

I'm trying to find info to repair the unit. So far Google has not been my friend, but I may not be asking the right question.

You've asked the right question and kramarat has answered it in a duplicate thread. I too suspect that the parts are proprietary and not generally available, but you could read the patent and attempt to find parts that meet that functionality. Good luck to you.

Yea, I didn't want to open a duplicate thread, but you were the only responder since I first posted on 31 Oct 2011 and I was getting a little desperate. Looking at the circuit boards inside, it does not look like the parts are proprietary. But, without a schematic it is hard to say, especially since I'm not that familiar with IC chips. Again thank you for your response.

I am willing to help if you can read the IC type numbers on the boards.

But the crunch with Watt/Var transducers is that when you have it working, you have to have calibration equipment which is more accurate than the transducer itself. This is a good part of why they are expensive to buy and repair.

It depends on how accurate it really has to be for your purpose - if it only fed a moving coil meter, the system error was never critical (because the meter itself was the biggest error).

My guess is that it has 3 identical single phase to neutral measurement boards in it. These are probably summed into a common output driver board for 4-20 mA or whatever.

It helps that you can compare 3 identical channels.

You have not said what is wrong with this, non-functional or obvious readout error. It is easier if it is the watt output "off" because VAr part needs current at 90 degree to volts to test.

My thoughts would go -

1. Is common power supply working/dead?
2. Is a common output driver damaged?
3. Identify output feeds of each phase to summer.
4. connect CT and VT of all 3 phases to same common AC voltage & single resistive load - see if each phase gives same output to summer.
5. If 2 phases output to summer agree and 3rd is "off" assume 3rd is faulty and compare levels at earlier stages in each board.

67model