How to test the Split MOPP

[Chandan N]

Hi All,

We have a device which is powered from mains 240V and secondary is 24V. Then the secondary 24V is stepped to 2kV thru switched converter. This 2kV required for the patient and it is delivered to patient thru hand held applicator.
From 24V there are other secondary circuits. One among them is control circuitry of applicator.
(not able to insert the image of the device block diagram). I will attach as soon as I find a way.

We can design 2 MOPP for the 2kV working voltage from primary to secondary. Here all secondary is included.

I would like to explore splitting the MOPP option.
Barrier A - Primary to secondary 2MOOP / 1MOPP (whichever is greater) for mains working voltage.
Barrier B - Secondary / HV circuit to applied part (consider full applicator as applied part) - 1 MOPP from secondary at working voltage of 2kV
Barrier C - Secondary / HV circuit to other secondary parts 2 MOOP (or 1 MOOP ??) at working voltage of 2kV.
Here Looking to make a separate module (box) for HV circuit which will be boxed and will meet the HV and CR / CP distances.

Query:
1. Is the above approach acceptable ?
2. If yes, how to test the full isolation at full device level ? Barrier A and Barrier B forms 2 MOPP. Do we need to test 1 MOPP separately ?

If the provided details are not enough, please ask queries.


Thanks,
Chandan N

 

[Chandan N]

Can someone please help to show how to add attachments to post ? Insert image is not working.

 

[tross]

Can someone please help to show how to add attachments to post ? Insert image is not working.

Can you try the "Attach files" option?

 

[Chandan N]

Hi Tross,
Thanks for the reply. Am not getting option to attach files ("attach files" icon not visible). I am using chrome Version 119.0.6045.105.
Any settings need to be updated ? Please assist.

 

[Chandan N]

I am able to attach the images thru Mozilla Firefox browser.
I will just re-write the query here, which will match with the image attached.

Hi All,

We have a device which is powered from mains 240V and secondary is 24V. Then the secondary 24V is stepped to HV thru switched converter. This HV required for the patient and it is delivered to patient thru hand held applied part.
From 24V there are other secondary circuits. One among them is control circuitry of applied part.

We can design 2 MOPP for the Peak HV working voltage from primary to secondary. Here all secondary is included. This could be simple approach. But it is difficult design for now, considering the other constraints.

I would like to explore splitting the MOPP option.
Barrier A - Primary to secondary 2MOOP / 2MOPP (whichever is greater) for mains working voltage.
Barrier B - Secondary / HV circuit to applied part (consider full applicator as applied part) - 1 MOPP (or 2 MOPP) from secondary at working voltage of HV
Barrier C - Secondary / HV circuit to other secondary parts 2 MOOP (or 1 MOOP ??) at working voltage of HV.
Here Looking to make a separate module (box) for HV circuit which will be boxed and will meet the HV and CR / CP distances.

Query:
1. Is the above approach acceptable ?
2. If yes, how to test the full isolation at full device level ? Barrier A and Barrier B forms 2 MOPP. Do we need to test 1 MOPP separately ?

If the provided details are not enough, please ask queries.


Thanks,
Chandan

 

[Chandan N]

Additional queries:

Query:
3. what we should consider for Barrier B ? - 1 MOPP from secondary circuit at Peak HV working voltage ?
Then total Barrier voltage becomes - 1 MOPP at mains working voltage (230Vrms) - Test Voltage of 1.5kVrms + 1 MOPP at HV Working voltage lets say 2kV - test voltage of 3.414kVrms. For testing the barrier - should we test these barriers separately (A & B)? If we test together then are there any chances that any one barrier may fail due to unequal capacitance at each barrier ?
4. Applied part has both HV and Low Voltage signals - What shall be the barrier here ? HV is required for patient so there is not protection of patient. 1 MOOP from the HV circuits at the peak HV working voltage - i,e 1 MOOP from secondary circuits?

 

[Chandan N]

Hello,

Can anyone help here ?

 

[mr9000]

You should definitly split the testing of the barriers and test each barrier seperately.
But if I understand correctly, the same barrier for 1 MOPP mains and 1 MOPP HV working voltage just has to be tested for the higher testing voltage of both conditions.

 

[Chandan N]

Hi mr9000,
Thanks for the response

Yes you are right, 1MOPP for mains and 1MOPP for HV working voltage are to be tested at different test voltages.
Here is am confused, in a final product after assembly, where we do not have access to internal secondary / HV circuits, how to test the 2 MOPP ? If we apply higher test voltage, barriers may fail due to unequal distribution of the test voltage in 1st MOPP and 2nd MOPP.. Any thoughts on this ?

 

[mr9000]

Why do you want to test in the final product after assembly without access?
Lab tests for 60601-1 allow white box testing, you can open the device and just test the barrier as labeled in the insulation diagram. A certified test lab will definitly open the device and look what's inside. Since Barrier B is inside the device, you cannot test Barrier B from outside.