Suppose I have a planar PCB transformer. The primary and secondary coils are printed on different PCBs. The core is inserted through these PCBs to link the two coils. The primary is at a low voltage and the secondary could be sitting at some 10 kV for example. Also, assume that the chosen PCB dielectric material has a high dielectric breakdown voltage capable of withstanding much higher voltages. The creepage and clearance requirements are also assumed to be met. I have the following questions:

• When should a transformer core be potted? Should it be potted at all? (the size of the planar transformer is less than 3 cm)
• Can I place the high voltage conductors of the secondary coil on the inner layers considering the high dielectric strength of the PCB.
• Air has a breakdown voltage of 3000 V/mm. If I wish to prevent arcing because of the 10 kV conductor, I can keep some 4 mm spacing between various components and the core. But, IPC 2221 specifies a much higher clearance requirement for the same. Is this to ensure reliability in various environmental conditions?
• "The core is at a floating potential that could be anywhere between 0 and 10 kV" - Is this correct?

EDIT: The secondary voltage is low (such as 5 V or 10 V) but with respect to a 10 kV reference.

posted 3 months ago

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3mo ago

jonathan_the_seagull‭

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