ROTATING FIELD ASSEMBLY (RFA)

RADIO FREQUENCY INTERFERENCE (RFI) SUPPRESSION

GENERATOR VOLTAGE ADJUSTMENT CONTROLS

TM-55-1930-209-14P-9-4 Water Purification Barges (NSN 1930-01-234-2165) Electric Power System Manual
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SR 4 GENERATOR SYSTEMS OPERATION C PROTECTION OF GENERATOR CIRCUITS The SR 4 Generator regulator and excitation circuits use many components for protection. Fuse (F1) is the type that opens very rapidly and gives protection against secondary damage caused by another component failure. This type of fuse is used because it is specifically made to work in circuits that have semiconductors. If the fuse needs replacement, it is important that the same amperage rating and type is used. A larger amperage rating or a fuse that does not open rapidly will not prevent damage to other components. F1 FUSE Surge suppression diode (CR11) prevents too high voltages that are abnormal (not normal) and transient (temporary) from causing damage to controlled rectifier (CR9) or field rectifier (CR10). Inside of rectifier module (A2) there are resistance capacitance circuits connected from anode to cathode of both controlled rectifier (CR9) and field rectifier (CR10). These circuits give added protection for abnormal transient peak voltages that can cause damage at (CR9) or (CR10). GENERATOR REGULATOR ASSEMBLY A2. Rectifier module. CR9. Controlled rectifier. CR10. Field rectifier. CR11. Surge suppression diode. Surge suppression diodes (CR7) and (CR8) are connected in parallel, electrically. CR7 is installed on the positive heat sink (E1) and CR8 is installed on the negative heat sink (E2). These diodes are connected in parallel to give the current capacity needed for suppression of any abnormal transient peak voltages that can cause damage to the rotating rectifiers (CR1 thru CR6). ROTATING FIELD ASSEMBLY (RFA) E1. Positive heat sink. E2. Negative heat sink. R6. Suppression resistor. E1 POSITIVE HEAT SINK R6. Suppression resistor. Suppression resistor (R6) gives a low resistance circuit from the insulated windings to the shaft and cores of the revolving field assembly (RFA). It this resistor was not installed, air friction on the windings and heat sinks can cause electrostatic charges. These charges can cause voltages to become high enough to destroy the insulation. Resistor (R6) is a 27,000 ohm resistor that lets these electrostatic charges run off as they are generated and prevents any voltage build-up. Because of the Value and power rating of resistor (R6). a ground failure at any point on the revolving field assembly (RFA) will not prevent the generator from operating normally and it will not cause damage to (R6). 41

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