Relative to IEC 61010-1 (UL61010-1)
I have a question on the effect of filtering in a circuit relative to the
overvoltage catagory (OVC )of that circuit.
My example is a power supply that has an OVC3 rating at the terminals.
I have considerable filtering in the front end - CM choke, Y1 caps to ground,
L:L caps, L:L MOV and L:L TVS diode.
After all this filtering I have tested the CM and DM let through from 6KV
surges (CM or DM) and to 4KV EFT and I see very little with my differential HF
scope set up.
I would argue that I have reduced considerably the surge/EFT exposure after
the filter.
Can I claim that the OVC catagory is reduced to OVC2?
Or must I treat the whole circuit the same for creepage and clearance all the
way through to the Switch Mode Controler transformer and feedback optos?
If you say I must treat it all the same help me understand why.
I know that the high pot testing would not make sense for the front end to be
evaluated to one level and then after the filter try to do another level.
If the source is OVC3 can I argue my circuit should be treated as OVC2 in its
entirety due to the protection?
Thanks
Chris Wells
