26SI Series Alternator – Component Description



Illustration 1 g00824798

Alternator Components (M1 Series)

(1) Fan

(2) Front Frame

(3) Stator

(4) Rotor

(5) Field Winding

(6) Regulator

(7) Capacitor

(8) Rectifier

(9) Rear Frame

The illustrations below show the 35 amp alternator (M1) and the 65 amp alternator (HDB).

Stator



Illustration 2 g00824809

M1 Series (35 amps)

(3) Stator

(A) (B) (C) Stator leads



Illustration 3 g00824931

HDB Series (65 amps)

(3) Stator

(A) (B) (C) (D) Stator leads

Stator (3) consists of a stator core and three independent windings. As the rotor turns, a varying magnetic field causes the stator windings to produce three-phase AC voltage. The stator is supported by the front frame and by the rear frame.

In Illustration 3, stator lead (D) has a black mark. The lead that has the mark is connected to the neutral point of the stator.

Rectifier



Illustration 4 g00824961

M1 Series

(8) Rectifier

(10) Positive Diodes and Negative Diodes

(11) Exciter Diodes



Illustration 5 g00824963

HDB Series

(8) Rectifier

(10) Positive Diodes and Negative Diodes

(11) Exciter Diodes

Rectifier (8) is a three-phase full wave rectifier. The rectifier changes the AC voltage that is produced by the stator to DC voltage. The rectifier contains positive diodes and negative diodes (10). The DC voltage from the positive diodes and from the negative diodes is delivered to the battery terminals.

The rectifier also contains excitation diodes (11). The DC voltage from the excitation diodes and from the negative diodes energizes the field winding.

Field Winding



Illustration 6 g00824993

HDB Series

(5) Field Winding

Field winding (5) is a stationary coil that provides a magnetic field for the rotor.

Rotor



Illustration 7 g00825072

HDB Series

(4) Rotor

Rotor (4) consists of a shaft and a magnetic core. The rotor rotates on the shaft. The rotor provides a magnetic field between the field winding and the stator.

When current flows in the field winding, the core is magnetized. One side becomes the “N” pole. The other side becomes the “S” pole. With this form (pawl pole), both poles are magnetized by one field winding. The “N” pole and the “S” pole are separated by an insulated ring.

Regulator



Illustration 8 g00825086

M1 Series

(6) Regulator



Illustration 9 g00825087

HDB Series

(6) Regulator

Regulator (6) limits the output voltage of the alternator to a preset value by controlling the current through the field winding. The regulator electronically switches the connection between the field coil and ground. The switching occurs at variable rates. The regulator is mounted inside the rear frame. The regulator is totally enclosed. The regulator cannot be adjusted.

Capacitor



Illustration 10 g00825089

M1 Series

(7) Capacitor

Capacitor (7) performs the following tasks:

  • The capacitor protects the rectifier diodes from high transient voltages.

  • The capacitor smooths the output of the rectifier.

  • The capacitor suppresses radio interference.

  • The capacitor reduces electrical noise.

The capacitor is mounted inside the rear frame. The capacitor is on top of the rectifier.

A resistor is connected in series with the capacitor. The resistor is inside the component.

Note: The HDB series alternators do not contain a capacitor.

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