In article ,
Winfield Hill wrote:
[.. neon sign xformer ..]
The problem with switching transformer primaries with triacs is
the high inrush current that can develop.

Yes, but not, I think for the reason you suggest.

The secondary capacitance of the transformer reflects back into the
primary. There is a primary leakage inductance that is intentionally
built into the transformer to limit the current secondary to under (IIRC)
6mA. Between these two effects, you end up with a funny ring when the
switch closes. It could be that something in this is getting his triac.

Also the OP didn't say anything about snubbing. The triac may be refiring
on the dv/dt when it switches off.

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