KIT-TRIM CAB 4384609 - Caterpillar

Introduction
The Statically Regulated Controlled Rectifier Generator gives improved performance and longer service life by applying a method of excitation which is controlled by an automatic voltage regulation system that contains no moving parts. The generator voltage build-up system uses only one moving part: a relay, which operates only when the generator is started or shut down.Generation Of Voltage
The generator is constructed with the armature coils wound on stator (A) and the field coils wound on the rotor, designated in the wiring diagram as rotating field (B). The field coils are wound on magnetic steel that will retain a small amount of residual magnetism. The rotating field is connected directly to the engine flywheel through the generator shaft and coupling.As the engine turns rotating field (B), a small amount of alternating current voltage is generated in stator (A) by the influence of residual magnetism in the rotating field. A portion of this alternating current (AC) is rectified to direct current (DC) and this portion is directed back to the rotating field to increase its magnetism. The procedure of excitation can be traced on the SRCR Generator Wiring Diagram by following the path of AC power form stator (A). This AC power from phase 1 and phase 2 passes through noise suppression assembly (V) to power rectifiers (D) [installed on main heat sink (E)] which rectify these two phases of AC power to provide two phases of half wave DC power. These two phases of DC power then continue through controlled rectifier (J) to rotating field (B). To sustain current in rotating field (B), when no current is flowing (because of no circuit from phase 3), another circuit from the negative (-) end of rotating field (B) [through field rectifier (F) mounted on auxiliary heat sink (H) to the positive (+) end of rotating field (B)], maintains a flow of current due to self induced voltage of the magnetic field. A mechanical analogy of this circuit is the action of an engine flywheel as it maintains crankshaft rotation between the power strokes of the individual pistons.
CONTROLLED RECTIFIER SYMBOL
1. Anode. 2. Cathode. 3. Third terminal (gate).Controlled rectifier (J) is, in effect, an "on-off" valve that can either allow current to flow or can stop the flow of current through the excitation circuit. Controlled rectifier (J) has the usual rectifier terminals, anode (1) and cathode (2), and a third terminal (3) that, for explanation purposes, will be referred to as the "gate". When gate (3) receives an electric impulse, it takes approximately three micro-seconds (.000003 second) for controlled rectifier (J) to "turn on" and allow current to flow. The controlled rectifier stays "on" until no current is flowing; then it turns "off". Because of no circuit from phase 3, current does not flow once during each complete cycle. Therefore, controlled rectifier (J) is "off" once each cycle and gate (3) must receive a signal to "turn on" the controlled rectifier some time during the next cycle.The timing of the signal to gate