Getting rid of Isolation Transformer

[tross]

Hello all,
If a medical grade power supply is being used in the device, is it ok to get rid of the bulky isolation transformer? Are there any disadvantages (or risk to patient and user) of not having the isolation transformer? Of course the medical grade power supply will be there to provide 2 MOPP (Primary-Secondary).
Thanks.

 

[Peter Selvey]

It's hard to say without the details of your particular device such as ratings, classifications, isolation plan and basic design.

 

[tross]

Hi @Peter Selvey,
Clause 8.11.1 requires device to have isolation from mains. So, I was wondering if a power supply such as, for eg. MFLS400-1312-TF from Bel Power solutions, can be used to satisfy the requirements? Or does it have to be the bulky toroid isolation transformer? The isolation transformer is making the device heavy. And if we are using a medical grade power supply, I did not see the point of keeping the isolation transformer. However, I am not sure if it ok to remove the isolation transformer.
Thanks

 

[Peter Selvey]

OK, this is just a mattery of terminology.

There are two types of power supplies, one an old clunky "linear" power supply and the modern is the "switching" power supply. One has a relatively large 50/60Hz transformer running directly from mains and the other has a much smaller high frequency transformer that has electronics before the transformer. In safety, we consider both of these to be an "isolation transformer". So when you say is it OK to "get rid of" or "remove" the isolation transformer it didn't make sense.

Anyway, yes, this is very common. In fact, linear power supplies are fairly rarely used these days, they are heavy and inefficient. Of course it should be medical grade if the design needs it.

 

[tross]

Thank you for the clarification. I appreciate it.