VALVE GP-CHECK 2019329 - Caterpillar

from phase 1 and phase 2 passes through noise suppressor (FL1) through fuses (F1 and F2), wires (35 and 36) to the power rectifiers (CR3) and (CR4) mounted on heat sink (E1) which rectifies the AC power to provide half wave DC power. Voltage surge suppression diodes (CR7 and CR10) across power rectifiers (CR3 and CR4) limit abnormal transient peak voltages on the power rectifiers. Fuses (F1 and F2) are the "fast blow" type and provide protection against secondary damage of the excitation circuit if any one component should fail or malfunction.The half wave DC power from the rectifiers continues from heat sink (E3) through regulator gain resistor (R1), wire (30), and noise suppressor (FL1) to the positive "+" end of revolving field (L3). To sustain current in revolving field (L3) when (CR1) IS NOT conducting (because of no circuit from stator phase 3) there is a circuit from the negative "-" end of the revolving field to the positive "+" end of the field. The circuit is from terminal (26) through noise suppressor (FL1) to terminal (27) through wire (27), field rectifier (CR5), regulator gain resistor (R1), through wire (30) to terminal (28) and through the noise suppressor to the positive end of the revolving field. This circuit maintains a flow of current due to self induced voltage of the magnetic field. A mechanical analogy of this circuit is: an engine flywheel as it maintains crankshaft rotation between the power strokes of the individual pistons.Surge suppression diode (CR8), and voltage surge suppressor (A2) across field rectifier (CR5) minimizes voltage surges (spikes) in the excitation circuit to protect the field rectifiers (CR5).
CONTROL RECTIFIER SYMBOL
1. Anode. 2. Cathode. 3. Third terminal (gate).Control rectifier (CR1) 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. A control rectifier has the usual diode 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 a control rectifier to "turn on" and allow current to flow. The control 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, control rectifier (CR1) is "off" once each cycle and "gate" must receive a signal to "turn on" the controlled rectifier some time during the next cycle.The timing of the signal to the gate of the control rectifier (CR1) is a function of regulator assembly (A1). As generator load increases, regulator assembly (A1) signals the "gate" of the control rectifier earlier in the cycle, permitting a longer excitation time to the revolving field therby providing the required additional excitation to maintain rated voltage with increased load. When generator load decreases, regulator assembly (A1) signals the "gate" later in the cycle and excitation time is less. Even