2 Pole Regulators
The short frame starter generators typically use the 2 unit or 2 pole regulators. These units regulate the output of the generator basically the same way the 3 unit or 3 pole units do. The major difference is the way the voltage and current control units are constructed.
In the 3 unit version there is a unit that is the voltage regulating unit and a separate unit for the current limiting function. In the 2 pole unit these two functions are combined in one unit. The voltage coil is wound with very fine wire and is shunt connected across the [A] terminal input to ground. Wound around this coil is a series winding of very heavy
wire, just like the winding in the current regulating section of the 3 unit or pole regulator. With the two coils on the same pole piece, only one set of contacts for the regulating function is needed. The pull from the voltage winding and the pull of the large series winding both act on the contacts. If the Voltage gets too high, the contacts break and reduce the generator output. This
reduces the pull on the contact arm and the contact goes back shut and the generator is full fielded again and the output comes back up. As in the 3 pole unit the contacts vibrate at a very fast rate, like 300 times per second. The series winding on the outside of the voltage winding adds to the magnetic pull on the arm by the voltage coil, so if the current is too high, this also controls this
same set of contacts. The cut-out section is exactly the same in both units. To save space and avoid some duplication, please see the 3 Pole Regulator article for a more detailed explanation of how a voltage regulator controls a generator.
2 Pole Regulator Diagram
CAUTION: Many agricultural applications use a 2 Pole Regulator on equipment with a conventional generator. These units look EXACTLY LIKE the units used with starter-generators. THEY ARE NOT INTERCHANGEABLE!!! The current control will likely be set way too high. CHECK YOUR SPECS!!
Click the picture for a closer view