Question about railroad signage

[nah00]

So I recently got a set of tunnel portals and on the back they came with this sheet of railroad signage. I was able to figure out what most of them are but there are a few that are still stumping me and I haven't been able to figure out.

 

I know the picture is a bit small but the ones I'm trying to figure out are the square and circles with Xs on them next to the yellow and green speed control signs and the white one with the red diagonal slash below the end of electric line one.

[railsquid]

Can you post a larger image and maybe highlight the ones you can't understand?

[nah00]

Here's a better picture with the signs in question circled.

[bikkuri bahn]

The sign on the left is a whistle post:

http://www.isok.jp/rail/term/term_ki/whistb.htm

 

The one on the lower right is for a dead section on an AC line, the boundary between either:

1.20kV and 25kV

or

2. 50Hz and 60Hz

[nah00]

I thought that's what that one was but it looks a little different from the whistle post sign (the x doesn't reach the edges of the real sign).

 

I figured the other one was some kind of marker for something electric but couldn't find any pictures of it on any poles. Found another one that was a yellow circle with two diagonal black lines on it that marked a change too.

[SuRoNeFu 25-501]

The one on the lower right is for a dead section on an AC line, the boundary between either:

1.20kV and 25kV

or

2. 50Hz and 60Hz

This site clearly explains (though mainly in Japanese) about signposts placed near dead sections...

[nah00]

That site is exactly what I was looking for, especially for the signage sequence coming into and going out of the dead section.