EBME Forums Forums Maintenance Test Equipment DNI 454a ESU analyzer help

I found a real picture of REM/ARM on the Internet,It looks like it actually functions like the decade resistor box in the youtube video.Just to test the resistance value of the unipolar negative plate,Simulation Patient Contact.

I check that the "CURRENT LOOP" leads go inside the 454a host,Looks like a current transformer principle,And it can only test AC current, DC current does not work.
Of course the ESU current has always been of the high frequency AC type.

I have QA-ES -II and DNI/FLUKE 454a,I found that the display effect of 454a is the best, the actual visual experience of QE-ES II is not very good, because the displayed number is very small.Observe the power value or current value, need to look very carefully。
454a only responds to AC signals, QA-ES II responds to either AC or DC,Of course ESU has always been an AC signal.
So 454a is more like the principle of induction measurement, and QA-ES II is more like the principle of attenuator measurement---This is my actual feeling, may be wrong

Good pictures of the module (a nice find). That 15 pin D-shell connector looks a bit vulnerable (especially after some years of use). Obviously the Active (yellow), Dispersive (blue) and Ground (green) sockets pass through to mate with the main unit below (supposedly measuring active and dispersive currents for comparison along the way). So it looks like you could still carry out ESU output checks as usual. However (and as made clear in a warning label on the module) you should not operate the ESU when the Patient Return Inputs (red sockets) are connected as a substitute for the ESU dispersive (return or "plate") electrode.

You will have already noticed that any of the modules hide the CURRENT LOOP sockets of the main unit. I have been wondering about what is behind those sockets. It would be nice to see the 454A circuit diagram(s). However, after 0:37 in this video you can see the guy making use of the CURRENT LOOP sockets.

I agree with your comments about the 454A - versus - the QA-ES. Although it has (had) "old technology" (early 1990's) I would say that the 454A is the more useful of the two ... at least to the "deployed" biomed. The QA-ES is far too bulky to lug about; OK as a workshop based piece of test kit, maybe.

You're spot on about the displays too. Nice big digits for the Watts reading on the 454A. Meanwhile the display on the QA-ES has hardly evolved from the original Metron version (early 2000's) ... in fact I prefer the original one (nice colour scheme, at least).

By the way, it seems that the latest Fluke catalogue only lists the QA-ES III under Electrosurgical Analyzers ... so it looks like not only the 454A but also the RF-303 have been discontinued (since around 2007 or so in the case of the 454A). However, BC Group (BC Biomedical) used to market what looked like an improved "454A" as the ESU-2300 (it has all the features, without the need for modules) ... complete with USB-B comm connector (wow)! Not sure if that one (c. 2012) is still available. According to the manual, it uses an RF current transformer to convert the high frequency RF signal from the ESU to a voltage signal.

Lastly, I'm sure you will find this presentation interesting. For instance, the "What are we measuring?" graphic(s) on page 4.

... better make that page 13.

I found a physical picture of {454A Auxiliary Test Load module (REM/ARM&Return Fault monitor, REM/ARM)} module.Both modules (CURRENT LOOP) are vacant


But some external load modules have (CURRENT LOOP)(25ohm、75ohm) and some don't（125ohm）, I don't know why

According to the conventional theory, an external load (CURRENT LOOP) should be connected, because this is the entrance to obtain the induced current

I am lucky enough to have both a QA-ES ii and a 454a analyzer。
From https://www.slideshare.net/merwine/5th-generation-esu-technology-june-2009this documentation I found many errors,For example, QA-ES ii does not use capacitors, but uses impedance matching technology.The documentation says it's a capacitor.And the analysis is not objective. It has been emphasized that the technology of BC GROUP is very advanced.In addition, the QA-ES II uses a resistor with 0 inductance, and there is no inductance at high frequencies.
This doc looks more like a salesman's marketing gimmick ^_^

QA-ES II uses impedance matching technology, using AD834 multiplier
454a uses the principle of current sensing, using the LT1088 thermal conversion principle, so QA-ESII responds to DC signals, and 454a only responds to AC signals
Fluke's latest QA-ES III analyzer, I don't think it is a revolutionary innovation, the selected solution may also be AD834 or a similar chip, maybe a higher precision resistor is selected for the load resistor, but I think this has no practical value , the only bright spot is that QA-ESIII has increased the frequency display function, but this is actually not important

I think you may be mistaken (probably looking at the under side of one of the REM/ARM etc. modules).

I can't see that you would want to involve the CURRENT LOOP sockets when using any of the load modules. So much for "conventional theory"!

Well, you're right (see page 5 of the document); but to be fair, the author was very experienced in the product development of a good number of ESU analyzers. But yes, he was working for BC Group at the time of the presentation.

However, personally I agree with him ... if "money was no object" I would go for the latest ESU analyzer from BC Group (which is the ESU-2350, I believe).

I believe you're right. Well spotted!