Carl Henning

Finally, the post you all have been waiting for – electrifying the stamp mill. (Ok, it’s the post I have been waiting for.)

Burning 20 cords of wood a day was getting expensive, even though the same company owned the lumber, the railroad, the mines, and the mill. This brings us to the famous story of Edison versus Tesla, DC versus AC. Edison was convinced that the future was DC (Direct Current). Tesla was in favor of AC (Alternating Current). In the long term, AC won of course. AC can have the voltage changed using a transformer; DC cannot. The benefit is that you can use smaller wire for the long distance, “high power lines.” Smaller wire because the higher the voltage, the lower the current. But people do not want 13,600 volts in their house. Not safe. So it’s transformed down to 115 volts. (Actually it’s 230 volt from a grounded, center tapped transformer secondary. You should know these things.)

In 1892 the mill owners started looking for a company to bring in AC from a hydroelectric plant they wanted built on a stream 13 miles distant. Westinghouse stepped up. They think this was the first long distance transmission of electrical power.

But most of the motors were DC. The hydro plant generated DC. Transformers were not commercially available yet. So they used MG sets, Motor-Generator sets. At the hydroelectric plant a DC generator drove an AC motor to convert to AC and step up the voltage for transmission. At the mill was another MG set; this time an AC motor drove a DC generator for plant power, including a DC motor to run the stamps and to run a line shaft through the machine shop. Individual machines were powered from the line shaft via a canvas belt.

All was installed in 1893. The engineer threw the knife bladed switch to connect the power and start the motor… and nothing happened. Diagnose, troubleshoot, and then the equivalent of “Is it plugged in?” There was a break in the transmission line three miles from the mill.

Now for pictures only an electrical engineer can love: