Section 3
DESCRIPTION & COMPONENTS
with a 62 Hz AC frequency (62 Hz equals 3720 rpm). At the stated
Circuit Breakers:
Each individual outlet on the generator is protected by a circuit breaker to prevent overload.
Rotor Residual Magnetism
The generator revolving field (rotor) may be consid- ered to be a permanent magnet. Some “residual” magnetism is always present in the rotor. This residu- al magnetism is sufficient to induce a voltage into the stator AC power windings that is approximately
Field Boost Circuit
When the engine is cranked during
Notice that field boost current is always available dur- ing cranking and running, this is because the SSR is energized the whole time. The diode (D1) prevents or blocks the Voltage Regulators higher DC output from reaching the Wire 14 run circuit.
Field boost voltage is reduced from that of battery voltage by the resistor (R1), and when read with a DC voltmeter will be approximately 9 or 10 volts DC.
Operation
STARTUP:
When the engine is started, residual plus field boost magnetism from the rotor induces a voltage into (a) the stator AC power windings, (b) the stator excitation or DPE windings, (c) the stator battery charge wind- ings. In an
ON-SPEED OPERATION:
As the engine accelerates, the voltage that is induced into the stator windings increases rapidly, due to the increasing speed at which the rotor operates.
FIELD EXCITATION:
An AC voltage is induced into the stator excitation (DPE) windings. The DPE winding circuit is completed to the Voltage Regulator, via Wire 2, Excitation Circuit Breaker, Wire 162, and Wire 6. Unregulated alternat- ing current can flow from the winding to the regulator.
The Voltage Regulator “senses” AC power winding output voltage and frequency via stator Wires 11S and 44S.
The regulator changes the AC from the excitation winding to DC. In addition, based on the Wires 11S and 44S sensing signals, it regulates the flow of direct current to the rotor.
The rectified and regulated current flow from the regu- lator is delivered to the rotor windings, via Wire 4, and the positive brush and slip ring. This excitation current flows through the rotor windings and is directed to ground through the negative
The greater the current flow through the rotor wind- ings, the more concentrated the lines of flux around the rotor become.
The more concentrated the lines of flux around the rotor that cut across the stationary stator windings, the greater the voltage that is induced into the stator windings.
Initially, the AC power winding voltage sensed by the regulator is low. The regulator reacts by increasing the flow of excitation current to the rotor until volt- age increases to a desired level. The regulator then maintains the desired voltage. For example, if voltage exceeds the desired level, the regulator will decrease the flow of excitation current. Conversely, if voltage drops below the desired level, the regulator responds by increasing the flow of excitation current.
AC POWER WINDING OUTPUT:
A regulated voltage is induced into the stator AC power windings. When electrical loads are connected across the AC power windings to complete the cir- cuit, current can flow in the circuit. The regulated AC power winding output voltage will be in direct propor- tion to the AC frequency. For example, on units rated 120/240 volts at 60 Hz, the regulator will try to main- tain 240 volts
BATTERY CHARGE WINDING OUTPUT:
A voltage is induced into the battery charge winding. Output from these windings is delivered to a Battery Charge Rectifier (BCR2), via Wires 55A, 66A and 77A. The resulting direct current from the BCR is delivered to the unit battery, via Wire 15, a 10 amp fuse, and Wire 13. This output is used to maintain bat- tery state of charge during operation.
10 Amp BATTERY CHARGE WINDING OUTPUT:
A voltage is induced into the battery charge winding. Output from these windings is delivered to a Battery Charge Rectifier (BCR1), via Wires 55, 66 and 77.
Page 12
