Design for 1Kv on transformer windings (which magnet wire?)

Use what is referred to as "double strength" magnet wire. As long as you do not go beyond 300 turns, you do not need to worry about one secondary turn arcing to another. That is only nine volts per turn. You can layer wind it, where you place the turns very neatly next to each other, tape over that layer as it finishes traversing the bobbin face, and continue on the next layer. Continue in like fashion until the total turns count is reached. You can test how many turns fit across the bobbin face, and determine an ideal per layer turns count as well.

The tape (3M transformer tape) between each layer is additional protection. one and one half turns of tape. It is also always good to have the turns not go all the way to the bobbin margins, as:

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The straight line is the bobbin face, the O's are the wires in cut away view (on end). note their unequal length. Layering one mil transformer tape over that seals one layer's potentials from another. Mainly because of the gaps near the bobbin margins

I made secondaries that had 4kV on then by the time they exited the transformer. I think you'll be OK with what you have. I think you'll find that it will pass all tests by 2:1 factors or the like. The construction is what is important. You wire is already top stuff.

Kapton is a little firm, and does not do much conforming to the winding undulations. 1 mil or 1.5 mil 3M transformer tape (or like brands)will allow sealing one layer's turns from another, and from other windings as well.

Without the wire gauges and bobbin sizes it would be hard to make any declarations about construction. Our switchers usually had the primary at the bobbin base, and subsequent windings went on top of that, after several layers of one mil transformer tape at 1500 volts per mil.

There are inter-winding capacitance issues and other things to contend with (or not).

I hope it goes well.

Hello,

Besides the operational conditions, you must also take into account the expected over voltage at the mains connection. The expected over voltage depends on where your equipment is located (with respect to the mains supply) and of course the mains voltage itself. For fixed building installations (230Vac) it is 4 kV. When this voltage can be across primary and secondary, this adds to your working voltage. You have to take also into account any transient that may occur (across the safety insulation) because of the switching action of your bridge.

I would check with the wire supplier/manufacturer whether the wire has sufficient withstand voltage (under your operational conditions). If not, insulation should be provided by other means (several layers of insulation and minimum creepage distance).

Best regards,

Wim PA3DJS

When the going gets tough and you need some really good wire:

Then there are compartmentalized bobbins etc. so you can wind it staggered and the compartment packages would be in series.

I wouldn't agonize over it. If your wire is good for 1 KV, then you're fine.

Have Fun! Rich

You are OK as-is; a reasonable rule of thumb for Kapton is 3.9KV per mil (thousandths of an inch). I am stuck with 9 pounds of double coated wire for such applications; used maybe ten feet...

I made it a point to be friends with the local custom transformer winder. When I needed 100 feet of #40 they just gave it to me. If you need custom transformers, it is good to know who is making them for you.

Ahh...but ask for double build Kapton...