# Alternator Field Winding Question

#### doubledipsoon

Joined Jul 1, 2020
2
I have an older 12 volt battery-charging 1979 Sencenbaugh wind generator that I am testing. It has an 3 phase alternator with a field winding that must be excited, as opposed to the newer "permanent magnet" alternators. The manual says that 60 watts maximum should go to the field winding. According to theory, amps= watts over volts, so the amps to the field winding should be 60watts (the desired wattage to the field winding)/13.5 volts (battery bank at full charge). So the amps comes out to 4.4 amps. I just measured the Ohms off of the 2 field winding wires, and it came out to 6.5 Ohms, which allows only 30 watts to the field windings. So the big question is, how can I deliver 60 watts to my field winding? By the way, I won't be regulating the wattage to the field winding- I intend to keep 60 watts continually hooked up to the winding. I'm not an electrical engineer, I am self-taught, so I hope I'm thinking this out correctly. Thanks.

Joined Jul 18, 2013
28,768
Usually the wound field is on the rotor, a single field winding with two slip rings, the stator winding's are the 3 phase generated supply.
Post a pic or part number.
Max.

#### doubledipsoon

Joined Jul 1, 2020
2
I have an older 12 volt battery-charging 1979 Sencenbaugh wind generator that I am testing. It has an 3 phase alternator with a field winding that must be excited, as opposed to the newer "permanent magnet" alternators. The manual says that 60 watts maximum should go to the field winding. According to theory, amps= watts over volts, so the amps to the field winding should be 60watts (the desired wattage to the field winding)/13.5 volts (battery bank at full charge). So the amps comes out to 4.4 amps. I just measured the Ohms off of the 2 field winding wires, and it came out to 6.5 Ohms, which allows only 30 watts to the field windings. So the big question is, how can I deliver 60 watts to my field winding? By the way, I won't be regulating the wattage to the field winding- I intend to keep 60 watts continually hooked up to the winding. I'm not an electrical engineer, I am self-taught, so I hope I'm thinking this out correctly. Thanks.
Here's a couple pictures of this incredible machine- without the blades- three 6 foot long made from Sitka spruce- Low rpm, no noise, and do-able by 1 person.. OK, I'm about to hook up the three AC wires to their three phase rectifier, crank it, and hopefully see the volt meter take off. I figure 30 watts to the field winding will suffice.for testing it out. OK, I need terminals.

#### Dodgydave

Joined Jun 22, 2012
11,318
To regulate an Alternator you vary the Voltage across the Field windings, put 13.5V across the field, and see what voltage output you get?