buck and boost transformer

[lzielk]

Something I have never had to do...

Select, size, and wire a buck boost transformer.

Here's the application:

British built OD grinder.

The internal control transformer high voltage input tap only goes to 440v.

The actual input voltage is running high, 490v.

So the output side that is labeled 220v is actually putting out 278v.

This is needed to power a DC shunt wound motor, 1/3HP, I'm assuming about a 2 amp load max.

The original DC driver has failed, I believe because the voltage is too high. I can't find a direct replacement, but what I am finding all require 240v + or - 10%. So, I need to drop this about 20% to get from 278v to the 240v range.

OR...

I can go directly from the 490v line voltage to 240v, bypassing the control transformer. Which ever is more practical.

What do I need to order? I assume it will come with wiring diagrams to get where I need to go.

Any takers?

Thanks!

 

[LarryFine]

Here's a B/B calculator: http://www.buckboostcalculator.com/



Or, as you said, using a 480/240v transformer would give you 245v.

 

[topgone]

As mentioned above, just use a 480/240V transformer and be done with it! 245V is within the range of +-10%. I doubt the original driver failed because of a higher voltages! Something happened on that device driver for it to fail, insulation breakdown perhaps or deterioration due to constant use and age of the equipment!