Humidity Pre-Conditioning IEC 60601-1 (2005)

EEmags · Sep 13, 2011

Hello,
I am looking to verify the requirements of IEC 60601-1 (2005) subclause 8.7.4 (specifically touch current). I am currently developing a Medical device for use in the home. It is IP21.

Now per subclause 5.7, a Humidity preconditioning treatment needs to be performed prior to the leakage tests.

I was informed by an associate to precondition for 7 days. Now current 3rd edition standard only goes up to 48 hours and says the time can be extended if there is risk.

My associate no longer works with me and I am wondering where he got the 7 days from when the risk assessment has not even been done. I know the second edition of the standard includes a 7 day humidity statement for drip proof and splash proof equipment.

I feel like I am going insane right now looking for something that I will not find, but think is there.

Hopefully someone has an idea of what my problem is.

J0anne · Sep 13, 2011

EEmags said:
Hello,
I am looking to verify the requirements of IEC 60601-1 (2005) subclause 8.7.4 (specifically touch current). I am currently developing a Medical device for use in the home. It is IP21.

Now per subclause 5.7, a Humidity preconditioning treatment needs to be performed prior to the leakage tests.

I was informed by an associate to precondition for 7 days. Now current 3rd edition standard only goes up to 48 hours and says the time can be extended if there is risk.

My associate no longer works with me and I am wondering where he got the 7 days from when the risk assessment has not even been done. I know the second edition of the standard includes a 7 day humidity statement for drip proof and splash proof equipment.

I feel like I am going insane right now looking for something that I will not find, but think is there.

Hopefully someone has an idea of what my problem is.

Decide which standard you are going to conform with and conform.
Within the standard you conform to, you will find answers to your requirements.

Peter Selvey · Sep 14, 2011

The previous edition (IEC 60601-1:1988) had a 7 day test if there was an IP rating to be tested (i.e. IPX1 or higher).

Singapore also had a deviation (for IEC 60601-1:1988) for a 7 day test for all equipment.

For home use in a global market, it seems reasonable to use a 7 day test, given that there will be places like Singapore where the humidity can be high for long periods. Also, take into account the reason for the IPX1 rating - is it just for the rare case of spillage, or is it intended for regular exposure to water?

EEmags · Sep 14, 2011

Joanne,
Obviously we want to conform to the newer 3rd edition. The issue is that I want to make sure what the correct amount of time to precondition the unit is. Saying to go read "the standard" doesn't really help the situation, since I am asking about standards I may not know about.

Peter,
We are presently in a global market, so that would be a fair assumption as well. I'd rather not go off assumptions though. 48h vs 168h is a huge difference for leakage.

Peter Selvey · Sep 14, 2011

Sounds like you might be worried that the longer the humidity conditioning is applied, the higher the leakage.

In modern equipment humidity does not really impact leakage current, as water itself is not actually all that conductive.

There are special cases where water can affect insulating materials such powder insulation in metal enclosed heaters, or paper insulation in some older transformers. Water gets in, ions are created and things become conductive. In these cases there is always protection to prevent water getting in (i.e. sealing for the heater; impregnation for paper), and the humidity test is important to verify this protection is effective.

However, for most equipment insulation is constructed using modern plastics which don't absorb water, and the spacings are way too big to be affected by humidity. If there is any significant change, it's worth to find out why as it indicates a poor quality insulating material is used somewhere in the system.

What you will find that corrosion really takes off with the 7 day test. And there may be other problems if you have humidity sensitive parts. But the funny thing is, in a standard with a title that includes "essential performance", they don't care about performance at all after humidity test. Make sense?

Roland chung · Sep 14, 2011

The 60601-1:2005/A1(CDV) has modified the humidity treatment period, just go back to the old requirement (second edition).

Keep ME EQUIPMENT and its parts where the ENCLOSURE is classified as IPX0 in the humidity cabinet for 48 h.

Keep ME EQUIPMENT and its parts where the ENCLOSURE is designed to provide higher ingress protection against liquids in the humidity cabinet for 168 h.

EEmags · Sep 15, 2011

Peter Selvey said:
Sounds like you might be worried that the longer the humidity conditioning is applied, the higher the leakage.

In modern equipment humidity does not really impact leakage current, as water itself is not actually all that conductive.

There are special cases where water can affect insulating materials such powder insulation in metal enclosed heaters, or paper insulation in some older transformers. Water gets in, ions are created and things become conductive. In these cases there is always protection to prevent water getting in (i.e. sealing for the heater; impregnation for paper), and the humidity test is important to verify this protection is effective.

However, for most equipment insulation is constructed using modern plastics which don't absorb water, and the spacings are way too big to be affected by humidity. If there is any significant change, it's worth to find out why as it indicates a poor quality insulating material is used somewhere in the system.

What you will find that corrosion really takes off with the 7 day test. And there may be other problems if you have humidity sensitive parts. But the funny thing is, in a standard with a title that includes "essential performance", they don't care about performance at all after humidity test. Make sense?

Actually, we do have a very hydroscopic piece of material in our device. It is our heating element, which when water is absorbed, creates a more of a direct path (through the heating element) from an energized part from our primary to the enclosure.

Peter Selvey · Sep 15, 2011

Powder insulated heaters (with MgO) are normally sealed at the ends to prevent moisture getting in. If the seal is good, the length of the humidity test should not have any significant influence. If the seal is bad, then the test duration will affect the amount of moisture getting in and hence the leakage current (also, the possibility of test failure for dielectric strength).

It's going back a while, but remember working with a powder insulation heater that had a problem with a sealing process, that was only detected after the humidity test.

EEmags · Sep 16, 2011

I wouldn't put stock into the seal. Currently it is just a thin piece of Teflon adhered/heated onto the element on the inside of the device.

We have done a lot of testing. I know what works and what doesn't. I just want to make sure I am testing it right.

msarfraz · Apr 23, 2012

7 days humidity conditioning is Singapore deviation.......

Humidity Pre-Conditioning IEC 60601-1 (2005)

EEmags

J0anne

Joanne

Peter Selvey

EEmags

Peter Selvey

Roland chung

EEmags

Peter Selvey

EEmags

msarfraz

Similar threads