Where to buy Medical Grade Transformer

[GregH.]

Hello,

I am new to this forum.

First I would like to thanks all the participants for the quality of information you can find here.
It is amazing.

I am part of a start-up developing a medical device.
This medical device should comply with the IEC 60601-1.

The device is powered by an external power supply, that is 60601-1 compliant with 2xMOPP.

The device also includes a capacitor charger on the secondary side in order to step-up the voltage.
The capacitor charger chip is the LT3751 to reach up to 250V.
The capacitor charger includes a Flyback transformer in order to isolate the output stage from the input stage.
The isolation shall provide 2 MOPP as it is directly connected to the applied parts, type BF.

Therefore according to IEC 60601-1,
The transformer shall comply at least with the following paramters:
- creepage distance given on Table 12 : 8mm for 2MOPP @250V
- air clearance on table 12: 5mm for 2MOPP @250V
- dielectric strength on table 6: 3000V for 2MOPP @250V

I can't find yet on the market such transformers.

Anyone has an idea if I misunderstood something from the standard and could relax my requirements?

Or does anyone has an idea on how to provide this 2 MOPP in a different way?

Does custom transformers has to be developed usually for such applications?

Thanks in advance for your help
In feedback is welcome

Have a great day

 

[MedMartin]

Hi,

We also use the LT3751 with a custom transformer in some of our products.
There are some transformers for 60601-1 compliance on the market but as soon as there are special requirements you have to make your own transformer. Check also if there are particular standards 60601-2-xx for your product. There could be some exemptions or relaxed requirements ...

Best regards
Martin

 

[Al Rosen]

This manufacturer states they will modify their transformers to meet iec60601-1. Of course it will cost extra, but it may be worth looking into.

 

[GregH.]

Hi,

We also use the LT3751 with a custom transformer in some of our products.
There are some transformers for 60601-1 compliance on the market but as soon as there are special requirements you have to make your own transformer. Check also if there are particular standards 60601-2-xx for your product. There could be some exemptions or relaxed requirements ...

Best regards
Martin

Hello @MedMartin

Thanks for your feedback.

I could not find anything related to transformer in the 60601-2-xx related to my product.

I was wondering which standard is compliant with 60601-1 for a transformer that is not connected to the mains but simply as part of a secondary circuit.
while screening for existing transformers, I sometimes find some that are compliant with IEC 61558-1 sometimes with IEC EN60950-1 or others.

Question:
Which of these can be compliant with IEC 60601-1 ?

@MedMartin,
Do you have some names of manufacturer in mind for low volume production in case I need to go for a custom design solution, please?

Thanks for your help.

 

[GregH.]

This manufacturer states they will modify their transformers to meet iec60601-1. Of course it will cost extra, but it may be worth looking into.

Thanks a lot,
Do you know if they can do it for low volume production?

I contacted them few minutes ago.
I will update the thread accordingly for future reader.

Have great day

 

[MedMartin]

Hello GregH,

you have to check for clearance, creepage and test voltage requirements (test voltage for 1 minute for 60601-1).
I think any standard in the datasheet is better than no standard. Our transformers also have no 60601 certification but are tested during approval tests. Sometimes the notified body wants to perform additional tests.
Best is to check with your notified body what they want and present them your preferred solution.

Some names:
Risse Electronic GmbH
Coilcraft
or google for custom magnetics design in your area.

Best regards
Martin

 

[Pads38]

Greg,

I don't know where you are located - but we use several transformer manufacturers for small batch custom build. They all tend to have a good understanding of the 60601 requirements and can easily 'tweak' designs to suit, things like adding an extra layer of insulation.
Pricing is only slightly more than 'off the shelf'.

 

[GregH.]

@MedMartin
Thanks a lot for your inputs,

It seams that IEC 61558-1 and IEC 60950 shall both be fine.
The constrains are only on creepage distance, airclearance and test voltage for 1 minute.

The issue with most custom transformer manufacturer is the low volume constrains I do have.

 

[GregH.]

@Pads38
Thanks for your answer.

Do you have names to suggest or share, please?
All the one I have contacted so far are not interested due to the low volume I have 100 units only for the 1st batch.

Thanks for your help

 

[GregH.]

@Pads38 & others

Thanks a lot for your help

I was wondering if you could share names with me,
either here or on a private message please?

Thanks in advance
Best