[Amps] Step start

[Steve Thompson]

> Hi All,
> 
> The purpose of a step-start is (mainly) to let the HV caps load smoothly.
> 
> The "classical" way to make a step-start is to short the resistor in the HV
> transformer primary with a relay switched after a delay made with an RC.
> This delay is mostly arbitrary put to 1 or 2 s.
> 
> Why not switch this relay with a divider from the HV voltage ? With the
> right divider, you ensure that the caps are really loaded and not supposed
> to be ?

As other replies show, people do it both ways - as have I. One 
thought relates to the (very rare) situation where there's a fault 
in the transformer or ht system that results in heavy current draw 
and low voltage so the step start doesn't switch out. The step 
start resistor can/will explode with the dissipation unless its 
huge (been there...). A fixed timer results in the mains fuse blowing.

To be fair, if you've a fault like that then a blown resistor is 
probably the last of your problems.

Steve