Voltage Sensing Connections

[mcreeferson]

Hi all,

I am scratching my head on the final connections for my gen head. The main winding connections took me a minute, but I figured them out easy enough. It is the AS440 I am having trouble making heads or tails of, specifically leads 7 and 8. I am sure I am missing the obvious here, maybe I just need more sleep...

Here is a link to the datasheet for the as440 ( http://www.davidsonsales.com/docs_pdf/AS440.pdf), and I will attach the connection diagrams for the voltage switch to this post. There is precious little explanation in the AS440 datasheet, so am not 100%, what am I missing?

[dieselgman]

Leads 7 and 8 on your AVR will be your ac sensing connections.

dieselgman

[mcreeferson]

Right, but where to connect them on the switch? In positions 9 and 13 (VR7 and VR8 respectively on the diagram)?

Honestly, I am a bit thrown off by the diagram overall. I'm not at all certain what connections to make on the aux portion of the switch.

[dieselgman]

I would much rather interpret a line schematic... I don't suppose they provided that? It would appear that you will need to figure out a sensing connection at two of the generator output leads (either 120 or 240 and a neutral) before they go through the switching (or determine a static output terminal that will always carry your output voltage regardless of switch position) because it also appears that the switch outputs will change to another terminal with each switch change. I would draw the line schematic first. Is your generator a 12-lead 3-phase wired head?

dieselgman

[dieselgman]

I couldn't blame anyone for becoming confused with that switching diagram... You asked specifically about your AVR, but your confusion is apparently all about the rotary switch. For clarity, I would draw the entire thing out on paper including all leads and connections (generator head, AVR, switching and output terminal blocks). Then the obvious can be determined and the not so obvious brought into focus.

dieselgman

[mcreeferson]

Yes, it is a 12-lead 3-phase head.

I will see what I can do about sorting the diagram out, maybe I can squeeze a line diagram out of the manufacturer.

[mcreeferson]

I was able to get the schematic for the main part of the switch, not including the aux contacts, and it certainly helps clear up their spreadsheet version.

[mcreeferson]

Well, I feel a bit foolish. After a bit of time off on other projects I came back to this this morning and put in a solid hour of working the problem before I realized there never was a problem to begin with. All I need to do is connect my voltage sensing leads to U6 and U1 and be done with it. Regardless of my switch position, series delta or double delta, the sensing connections remain unchanged. I was so busy focusing on how my switch's auxiliary contacts were arranged and how to use them for voltage sensing, I failed to note that they were completely unnecessary for the task. 

[dieselgman]

Excellent! It is often the same for me when I come up against a difficult problem that has no apparent or obvious solution... taking some time off can bring clarity.

dieselgman