Is the grounding impedance 32A or 40A in IEC 60601-1?
April 26, 2021
These days, a friend of mine has been asking me about the content of CSA grounding impedance test.
I always remember 40a, 120s. But I don't know the source.
I have thought about this problem in the past two days.
During the trouble a lot of big guys, here to say thank you.
It's a great feeling to solve doubts!
According to the standard content of IEC60950 IEC62368:
It is known that Canada and the United States use 20A as the protection current rating of the power supply circuit of the power grid. There is no doubt that 40A and 120s are directly marked in 62368.
However, in IEC 60601, the description of grounding impedance is as follows:
Careful partners will find that Canada should play 32A according to the standards!
I was convinced at first that it was 32A.
I read several other home test reports, all 40A.
Later I checked Canadian medical standard can/csa-c22.2 No. 60601-1:14.
My God, as like as two peas IEC 60601! This CSA group is too lazy.
Later, I asked some experts, and then I followed their instructions
I first looked at the differences between IEC 60601-1 CSA countries:
Through this I know CEC: Canadian Electrical Code. Later, I went to check CEC:
This seems to be the basic specification of a country, similar to the European Union's harmonized standard. On the first page, I saw the special requirements for grounding impedance: can / csa-c22.2 No. 0.4-17
Good guy, it is directly stipulated here that the grounding impedance test shall not be lower than 40a, and the time is 120s.
But I'm not convinced. I don't understand why the Canadian standard doesn't specify this, so I went to see can / csa-c22.2 No. 60601-1:14 again.
My God, only when I see this can I understand that Canadian standards can be modified, replaced or even deleted from IEC standards. It can be seen that Canadian Standards are superior to IEC standards. It can also be understood that the special standard takes precedence over the general standard
So the problem has been basically solved.
The one who knows the origin of 40A is definitely a big man. I know why
But for those who play 32A, you are more careful.
In the future, when IEC 60601-1 achieves CSA and US difference, the grounding impedance is 40A and 120s.