For. Example the DC Alternator is capable of delivering :
2 kW at 750 RPM
4 kW at 1500 RPM
8 kW at 3000 RPM
1. The DC Alternator delivers constant DC Voltage at the terminals up to its rated load battery current or total full load & subsequently the voltage drops depending upon load & hence protect the Engine, Alternator & the load.
2. User settable DC Output voltage, DC Battery current & DC Overall current
3. The control panel gives signal to electronic governor of the engine to operate at sub-synchronous (settable) and super synchronous speeds (settable) to get optimum fuel consumption & hence increase efficiency of the system & further increases the life of the engine
4. Ripple will be less than 100 mV with battery & less than 300 mV with out battery
PRINCIPLE OF OPERATION OF DC ALTERNATORS
I. The rotor of the revolving field generates a rotating flux which induces the following emf’s in the stator. The alternator builds up voltage with the help of residual magnetism & mainly from the permanent magnets housed in the exciter stator.
II. The 3 Ph.AC from the main stator is fed to the Diode bridge.
III. The automatic Digital voltage regulator (AVR) receives the following signals.