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Re: Electrical Safety Phantom simulation [Re: MikeX] #74609 04/10/19 12:54 PM
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Neil Porter Offline
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What are you testing, the medical equipment or the PSU?


If you think hiring professionals is expensive, try hiring amateurs!
Re: Electrical Safety Phantom simulation [Re: Neil Porter] #74610 04/10/19 1:18 PM
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MikeX Offline
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Originally Posted by Neil Porter
What are you testing, the medical equipment or the PSU?

Both, as they form the ME Equipment.

Re: Electrical Safety Phantom simulation [Re: MikeX] #74612 04/10/19 3:15 PM
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Geoff Hannis Offline
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Correct! smile

And that's one of the reasons why swapping them around needs to be "discouraged"; another is the inadvisability of plugging the wrong "brick" into the wrong equipment. And yet another is when faulty "bricks" are plugged in (or maybe "half plugged in") to equipment in the forlorn (but unnoticed) hope that batteries will be charged up. frown

Cue:- colour coding, tie-wraps, yet more stickers ... and more "PM on the wards"! smile

I would venture to suggest that this could be a more fruitful line of research than the one our OP had described. That is:- can we come up with a practical method of keeping the many power supply "bricks" scattered around the typical modern hospital married up with their originally intended parent equipment?

By the way, what have the Wise Ones got to say about RFID tagging of power supply "bricks"? It could be yet another selling point (and a good one at that), I would have thought.

Re: Electrical Safety Phantom simulation [Re: MikeX] #74616 04/10/19 5:26 PM
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edovon Offline OP
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Originally Posted by Geoff Hannis
Originally Posted by edovon

My idea was to create internal different sources of leakage currents (low enough to do not harm people but above the permitted threshold)


How do you plan to simulate (demonstrate) low values of insulation resistance? think

As hinted at earlier, you may be better off (and produce more "real world" practical training sessions) by starting to collect faulty equipment that have the various "double fault" conditions already in place.



I was thinking to use metal layers in specific positions connected to a resistor connected directly to the protective earth of the device. Also the leakage currents would have a specific place to be measured.


Originally Posted by MikeX
Any training is mainly focused around how to use the particular safety tester and how to configure it for the equipment you are testing, in line with the EUT manufactures instructions.

Once the basics of BS EN 62353:2014 are known and how to implement them using your available test meter you are 90% there. Simulating faults really won’t provide much benefit.


My goal actually was to create something reproducible low cost and that could produce outcomes precisely (and hopefully accurate too). This idea was born with the aim of have something with pre-settable and verifiable values. But now, I am also thinking about using an already faulted equipment.

There was also an idea to implement this dummy in order to teach, not only to students, but to technicians of developing countries hospitals how to perform this testing.

Re: Electrical Safety Phantom simulation [Re: edovon] #74617 04/10/19 5:26 PM
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edovon Offline OP
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What do you think, instead, about the idea of creating a low cost "electrical safety analizer"?

Re: Electrical Safety Phantom simulation [Re: Geoff Hannis] #74618 04/10/19 5:31 PM
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edovon Offline OP
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Originally Posted by Geoff Hannis


I would venture to suggest that this could be a more fruitful line of research than the one our OP had described. That is:- can we come up with a practical method of keeping the many power supply "bricks" scattered around the typical modern hospital married up with their originally intended parent equipment?

By the way, what have the Wise Ones got to say about RFID tagging of power supply "bricks"? It could be yet another selling point (and a good one at that), I would have thought.


What do you mean? Sorry, I am not so much into the field to understand "scattered around"?

Re: Electrical Safety Phantom simulation [Re: edovon] #74619 04/10/19 6:27 PM
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Geoff Hannis Offline
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OK ... how about scattered around "found in"?

And power brick ... an equipment power supply (invariably a switch-mode type) that is similar in size, shape, and weight to a small brick, which plugs into the equipment via a fixed (relatively thin) cable at one end, and into the mains supply by a "mains" cable (generally detachable) with a fused 13A plug at the other. smile

Re: Electrical Safety Phantom simulation [Re: edovon] #74620 04/10/19 6:57 PM
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MikeX Offline
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Originally Posted by edovon
What do you think, instead, about the idea of creating a low cost "electrical safety analizer"?

Not going to be financially viable, as by the time it is certified (e.g. CE marked) and you have set up sales, distribution and calibration services it will be no cheaper than any of the current items on the market.
Existing tester manufacturers also provide training as part of the sales package so cover all aspects.

Sorry if it sounds like I am pouring cold water on your ideas but I am just trying to save you wasted time and effort.

P.S. I have made my own piece of equipment that I use when teaching medical electrical safety and testing. It has some probes (simulating ultrasound transducers) that have typical allowed leakage and faulty leakage. I also use a class II laptop power supply to show how half the mains can be measured on the DC output connector with respect to earth but then also show how the actual current to earth. Showing things like this may give more information than trying to have lots of faults that no one will remember. Anyone who does such training can soon knock up something similar.

Re: Electrical Safety Phantom simulation [Re: MikeX] #74628 09/10/19 7:06 AM
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Ian Chell Offline
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This thread is quite appropriate for me. I’m finishing off my stint of lectures to 3rd year biomedical students. Mike X is totally correct in his summation. I decided to go for electrical theory basics rather than trying to show them an automated tester.

I find it useful to hear others have struggled how to demonstrate double fault conditions. The main hurdle is that devices are too well made these days. I’ve even bought a genuine 1970s kettle off eBay to demonstrate dodgy insulation by using a raw insulation meter. Only killed two students so far (joke).

We even had an injector donated by Siemens but it’s too good as the plunger is now plastic. Still useful though.

Trying to emulate faults is credible but to teach and engage, I think I need to build up a pool of failed devices to show why you’re testing as well as grabbing their attention to make it sink in. It sounds as if my thoughts on PSUs are a good direction as Mike also demonstrates in his lessons.

If anybody out there is chucking any faulty medical device that’s useful for this purpose then I’d be grateful.

Re: Electrical Safety Phantom simulation [Re: edovon] #74630 09/10/19 4:41 PM
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edovon Offline OP
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Hello, I have decided to use old ECG to adapt their inner circuit to the one of "my" phantom (able to recreate leakage currents).

I am now looking for ecg refruibished, but in order to understand if I can use them, I want before to check their technical specification, and in particoular their circuits specifications.
Do you know where is it possible to find the patents? I would like to find the electronic design of ECGs.


thank you

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