Star-Delta Switch

[DanielCV]

Hello,

I am looking for a star-delta switch, I have emailed the guy from http://www.dsgnspec.com/ but got no answer - anyone knows if he is still selling this kit ?

Or have anyone seen any alternatives for that one ?

Thanks for your help,
Best regards,
Daniel

[Flux]

I have found speed to be the best signal for star delta switching. If you look up the data sheet for the 2917 tacho chip ( National or ON semiconductors or someone like it) the data will probably include a nice simple circuit to switch a relay from frequency. You can get frequency from your alternator from a little transformer or an opto isolator connected to a pair of lines.

You will need to set the circuit up for the number of poles on your alternator. If you want to switch a big relay or a contactor then you might need a pilot relay on the tacho chip to switch the big one.

Flux

[ChrisOlson]

I have found speed to be the best signal for star delta switching. If you look up the data sheet for the 2917 tacho chip ( National or ON semiconductors or someone like it) the data will probably include a nice simple circuit to switch a relay from frequency. You can get frequency from your alternator from a little transformer or an opto isolator connected to a pair of lines.

Check out Brian Smith's little tachometer board:
http://sites.google.com/site/rpmmeter/

It will operate a pilot relay, which in turn can operate a large latching or momentary relay to make the wye/delta switch.
--
Chris

[DanielCV]

Hello,

that one looks very good - maybe it´s also suitable for logging the rpm  - see my other topic called "Datalogger" ?

Best regards,
Daniel

[DanielCV]

Hello,

just got a reply from the person who did that PCBs - he does not sell them anymore

[ChrisOlson]

I was not aware that Brian stopped selling those little boards.  It was the slickest "turn key" method of doing wye/delta switching that I had found.

You could contact Craig at Coleman Air.  He indicated to me at one point that they have a wye/delta switch that is rpm-based and uses SCR's to do the switching instead of relays.

--
Chris

[scoraigwind]

There is something to be said for using current as a cue for switching.  Marlec did this with their old FM1800 control box for switching between transformer taps.  They used a current trasnsformer and some op amps with feed back to make it stable (ish).

As for a simple method to determine speed, the best idea I came up with was to build a pilot coil into the stator using very thin wire, and then power the star/delta relay off that.  It might be better to use 3 coils and a rectifier to get a cleaner switching action with DC. 

I confess I did not persevere with the thing and get it working well.  The problem with star/delta for me is that you are using 2 stator configurations, neither of which is really suitable for the mid-range winds where most of your energy is generated.