Member postings for Robert Graham

Many thanks James for your comments and guidance.

I did expect this motor for driving the thicknesser rollers of the machine to be a Dahlander winding, but measurements show two seperate sets of coils; seemingly this is quite a popular format for large cooling fans, where a simple thermostat, and no electronics, will enable a higher cooling rate when required.

The motor, perhaps like yours, is probably classifiable as old but as it was also capable of running at 2800rpm, I'm using the 4 pole windings and taking the top frequency up to 100Hz. It's not going to be used on a commercial basis, just amateur, so won't get used heavily.

Out of interest how did you discover that it was P73 and P74 that had to be changed to get the external variable voltage to the bigger range?

Rob

Thanks for that Robert - one then starts to think about the possible number of times you've fallen into that catergory; I do try to the polite thing but I'm sure I have been a guilty one too.

But the other aspect is that you have shared your knowledge and, as in this case, I searched 2 years after the original discussion and found a treasure trove of info.

i'm restoring a 1970's planer / thicknesser (for wood!) which has two 3 ph motors requiring the appropriate inverters.

Rob

Yep - the guidance works!! Again so many thanks even if those in the 2020 discussion are no longer seeing this.

The relevent list came from James Walker's posting of 25/05/2020, with particular reference to the settings for P73 and P74 - just how anyone found that these particular parameters are the key ones for this I just gasp at !!!

Rob

I've just joined this Forum because this thread gave me an answer - which I have yet to check - to the same problem that the Original Poster asked - why does the internal potentiometer allows me to run a 4 pole 3 ph motor up to 100Hz but the external pot will only go up to 50 Hz.

In my case I have a motor which is a 2 pole / 4 pole combination to allow 2 speed operation with an appropriate switching of the windings - there are 6 leads coming form the motor. I have done the internal change from star to delta on a previous motor but the thought of dismantling this motor and attempting to locate the star points put me off particularly when I found the AT4 - again a couple of years ago and have only got round now to trying it out.

So thanks to all of you who previously fully discussed this out, and I am hoping the guidance will work.

Rob