I put some comments below.
On 2023-11-06 14:08, Scott Xe wrote:
Last week, we received a sample of an induction hob from a supplier.
The unit is fitted with a 3-core power card and does not have a class
II symbol. The earthing core is terminated at a small copper pad on
the printed circuit board with a protective ground symbol (IEC 60417 -
5019) next to the terminal. It is shocking to note that the copper
pad is standalone and not connected to the unit circuitry. We made an
inquiry to the supplier and replied that the product was designed by
the engineer who left the company.
/JMW: That alone should indicate that you should have nothing to do with
the product, unless you are a test house, paid for assessing its safety./
I have two questions regarding the appliance. Firstly, can it be rated
as a class 1 appliance?
/JMW: If it passes all the safety tests for a Class 1 appliance, it is a
Class 1 appliance. But it remains a suspect design./
Secondly, what are the main purposes of installing a 3-core power
cable that has no obvious functionality?
/JMW: There is a strong temptation to do that if it's too difficult to
meet the Class II requirements./
Additionally, while examining the PCB layout, I noticed punched holes
for a resistor and two capacitors connected in series, with the
capacitors connected in parallel first. Currently, there are no
components present in those holes. I would like to know if these
components are necessary for EMC compliance.
/JMW: There is no way anyone can advise you on that, even if we could
see where the 'missing' components appear in the schematic. You have to
test it as it is and see whether it meets the EMC requirements./
Your advice is appreciated!
Thanks and regards,
Scott
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