What could be considered the workhorse of the alternator, the stator, as its name implies, does not physically move, but yet produces enough electrical energy to supply the needs of modern high tech vehicles. The stator is located inside the alternator sandwiched between the housing halves. So, how can a stationary electro-mechanical component produce electrical energy? In order to comprehend this concept, a thorough understanding of what components a stator is made and how those components working together cause the stator to produce electrical energy is recommended. Knowing and understanding this concept will aid in properly diagnosing a faulty or failing alternator.
The stator consists of two components, a round laminated iron core shaped like a circle with internal slots machined axially around the inside circumference of the core, and three equal lengths of non insulated laminated copper wire used for installing the electrical windings, each placed into a separate internal slot of the core similar to the other wires. Each stator slot is insulated from the stator winding. The outer circumference of the stator core can be seen sandwiched between the front and rear alternator housings when the alternator is fully assembled.
The three equal lengths of copper wire can be wound two different ways onto the stator core, which are the delta design and the wye design. Delta wound stators can be identified by having three identical eyelet terminals with the same amount of wires in each, which are secured to the rectifier containing the diodes. The windings in a delta wound stator are connected in parallel allowing for higher current flow at low alternator speeds or engine revolutions. Wye wound stators can be identified by having four terminals. The fourth terminal is the common or neutral junction for one end of the three windings. The three other eyelet terminals are attached to the rectifier which contains the diodes. Wye wound stators are connected in series allowing for higher voltage at lower alternator speeds or engine revolutions.
In the next article of this series of introduction to alternators, the working relationship of the rotor and stator will be discussed.
As always, if any procedure in this series of articles appears to be beyond the capabilities of the vehicle owner or driver, then testing and servicing the alternator should be performed by a professional or ASE Master Certified mechanic. The vehicle would have to be taken to a repair shop that employs these types of mechanics such as A & M Alternator Services located at 2419 E. Jackson St. in Phoenix, Auto Electric Specialists located at 5216 W. Lamar Rd. in Glendale, Village Auto Electric Service located at 19 N. Miller St. in Mesa, All Start Electric located at 13501 E. Chandler Blvd. in Chandler, Jordan’s Automotive Specialists located at 8718 E. McDowell Rd. #3 in Scottsdale, or Rob’s Quality Automotive located at 11801 N. Cave Creek Rd. in Phoenix