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

Hello everyone,I have a DNI 454a ESU analyzer,When I read the operation manual, I found that it has 3 loading modules, but I don’t know what these loading modules are for.Because the host already has a load resistance of 50 ohms-1550 ohms.
If you know the usefulness of these load modules please let me know, thanks




user manual:https://www.medwrench.com/documents/view/5647/fluke-biomedical-454a-dni-nevada-operators-manual

From memory, I believe these add-on modules came into their own when using the 454A with the (gold old) medTester 5000-C.

Specifically, the REM/ARM module or the combined REM/ARM and Return Fault module (RARF) were used during the medTester CQM (Contact Quality Monitor) Test.

The CQM test measured the resistance needed by the ESU to activate the CQM alarm.

The RARF was also needed for the medTester Return Fault Test.

But, as mentioned in Chapter 5 of the manual you refer to, those two modules were specifically aimed at a particular type of ESU (eg:- Valleylab Force 4B) so may, or may not, be of use when testing other ESU's.

The (nine) "Ohm Test Load" modules may be used in cases where ESU tests call for specific loads.

Do you have the modules? The one you show looks like a RARF.

Thank you for your reply.You mean the medTester 5000C, is it a safety analyzer?

Currently I only have a 454a host and I don't have these modules.

I'm learning to use the 454a analyzer properly,I found that "ACTIV" and "DISPERSIVE" are used for ESU energy analysis and RF current test. Is it correct to only connect these two interfaces?And "POWER GROUND" is generally not used?


In addition, I don't know the actual use of the "CURRENT LOOP" interface. When I press "AMMETER" on the system interface to enter, it is as shown in the figure below

And after pressing "AUXILIARY" to access, I saw the following prompt on the screen

I don't know if these are normal or if there is an error

Or the DNI Nevada 5000B (see page 3-30 of the manual).

The medTester 5000 is (or at least, was) a very handy piece of test equipment. At its core it permitted measurement of currents and resistances as they related to electrical safety. It allowed repetitive tasks to be automated using "autosequences" which could be customised. It could act as a portable data acquisition unit controlled by computer. With the right accessories (and a bit of imagination), it could almost "do everything" when it came to testing electromedical equipment - especially if you also had our old friend the Timeter RT-200.

In short, I would recommend that you add a medTester to your collection of antique biomed test equipment!

I should imagine that the Power Ground expects a jack plug - lead - croc clip to the ESU EUT (Equipment Under Test) chassis.

Yes; there is an error ... there are no modules in place!

You mean, if I'm doing ESU automated electrical safety testing, an ESU host，Also need a 454a analyzer, plus a module suitable for the 454a analyzer, and a Nevada 5000B (or 5000c) electrical safety analyzer, all of the above, to conduct ESU electrical safety automatic testing?

454A Auxiliary Test module (REM/ARM&Return Fault monitor, REM/ARM)--these two types are suitable for electrical safety testing？

454A Auxiliary Test Load module (10, 25, 35, 50, 75, 125, 330, 2000, 5000)--these 9 types are for supplementing the built-in resistance value? "Because the built-in resistance is from 50-1550, stepping by 50, it is impossible to have the special resistance values of 10, 25, 35, 75..."


I don't know if my understanding is correct, if not, I hope you can tell me

Short answers (I may add more later if I have time):-

1) No. Use a safety tester - automated or otherwise - for electrical safety testing (EST). But yes, the medTester* does EST (and much more).

2) No. Those modules are nothing to do with EST.

3) Yes and No. Use whatever loads - internal and/or external (modules) - are required. Individual ESU service manuals usually (or at least should) make clear which loads are required during testing.

In times gone by, some ESU service manuals may have made specific reference to the 454A, and which loads etc. should be used (some may even have also mentioned the medTester). Manuals usually also lay down step-by-step techniques (or checklists) for testing. Some are better than others in this regard, but I recall that it was hard to lay down generic testing procedures for ESU's. That is to say:- some had specific requirements. That did not matter too much when considering an individual setting (where only one type of ESU was being supported), but could be "fun" when many different ESU's were being looked after in different locations.

Lastly, you might enjoy this YouTube video if you have a half-hour to spare (it includes the 454A towards the end - where it is referred to as "old school")!

* If I have whetted your appetite for the medTester ... be aware that they only operate on 115 V (or, put it this way, sadly I have never come across a 220 V version).

Do you mean these 2 modules {454A Auxiliary Test Load module (REM/ARM&Return Fault monitor, REM/ARM)}Only used to test REM/ARM or Return Fault monitor function, not related to automatic test?
In other words, the above two modules can also be used in manual mode, is that what it means?

454A auxiliary test load modules (10, 25, 35, 50, 75, 125, 330, 2000, 5000) - these 9 types are only external loads.They are the same as the internal load, just the resistor values are different, I understanding this correctly?

I believe that both modules may be used either manually or in auto modes ("autosequences" etc.). See Chapter 5 of the manual.

Yes, the 454A has internal test loads from 50-1550 ohms. The (optional) add-on test load modules may be needed when testing special purpose ESUs. For example:- 25 ohms (eg, for thermal ablation) and 2000 ohms (eg, for orthopaedic surgery). Otherwise you shouldn't need them.

Notes:-

ARM: Aspen (later Automatic) Return Monitor
CQM: Contact Quality Monitor
REM: Return Electrode Monitor

Return Fault Monitor: continuously compares the difference between active and dispersive currents.

Note that in the YouTube video referenced earlier the guy used a resistance decade box to check the REM trip resistance. I'm guessing that's more or less what the REM/ARM modules do.

All I can say is that you refer to page 3-9 of the manual. But note well that, if experimenting with applying "external load configurations" you need to heed the warning about the requirement for a load resistance of "adequate power rating".

Lastly, don't forget two aspects that often get overlooked:-

1) The oscilloscope output. I always liked to check-out the various waveforms.
2) "Crest factor" (CF) - both 454A and QA-ES display these values.

Basically, CF= Peak Volts/RMS Volts. It is desirable to have a high CF when Coagulating tissue and a low CF when Cutting tissue. CF is an indication of how well an ESU output can Coagulate without Cutting. Typical values are around 1.4 for pure sine wave to about 10 for Coag.

Crest Factor is defined as a ESU's ability to Coagulate without Cutting. The ideal is to slowly shrink the top layer of tissue whereby the capillaries seal off bleeding without causing any further penetration or tissue necrosis. In order to achieve this ideal, the CF for Coag must be as high as possible - typically rated as a multiple of RMS (eg, CF of 7 to 10). If CF is high enough, the power under load will ideally drop to zero before cutting. This is also proof of a High Impedance source.

By the way, I've never used a 454A myself. The best I ever had to make do with was the Bio-Tek RF-302 (and before that, various "home made" options of the "needs must" variety).