DC Generators / DC Alternator

The conventional method to have auxiliary DC Supply for battery charging & other DC Loads is to use a diesel generating set of constant speed & a rectifier unit.
 Integrated Electric developed a variable speed DC Alternator for coupling with Diesel engine as a source of DC auxiliary power. The principle of working is as under. The basic generator will be just like any brushless AC Generator consisting of main stator, Main rotor, Exciter stator & Exciter rotor. The generator is of three phase, variable speed, variable kW output, 
 For Example the DC Alternator is capable of delivering:

• 2 kW at 750 RPM

• 4 kW at 1500 RPM

• 8 kW at 3000 RPM

SYSTEM FEATURES

• 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.

• User settable DC Output voltage, DC Battery current & DC Overall current

• 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

• 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..

• 3 Ph. AC from the main armature windings.

• 2 Ph. AC from the auxiliary winding.

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.

• DC Output voltage.

• 2 phase AC from the auxiliary winding.

• Speed feedback for frequency roll off

• DC Battery Current feedback.

• DC Total current feedback

The AVR uses these signals to compute the amount of excitation required to maintain the terminal voltage up to its rated current rating & reduce the terminal voltage on further loading of DC Alternator & hence protect the DC Alternator from over loading. The digital AVR also monitors the total overall load current & gives feed back signal to electronic governor to change the speed depending on load.
IV. The Exciter field induces 3 phase AC at 100Hz. in the exciter rotor.
V. The rotating diodes mounted in the exciter rotor rectify the AC voltage to DC Voltage and supply it to the Main rotor field winding 
VI. This regeneration continues and till the rated DC output voltage is achieved. The output voltage will be maintained at its rated value up to its rated current as indicated on the name plate of the DC Alternator.

DC GENERATOR
Generator using its bush less / AVR Alternator technology in 2008. Since then numerous organizations have performed extensive testing on our generators Agrowave assembles the genset to meet its' clients requirements by adding the appropriate diesel engine to our DC alternators. The engines are available in either a liquid or air-cooled version. Agrowave has designed this DC alternator incorporating state-of-the-art technologies and all new tooling to meet the increased performance demand for.

• Low Maintenance

• Low EMI Emissions

• Very High Quality Electrical Output

• Light Weight

• Low Fuel Consumption

• Low Acoustic Noise

• High and Low Ambient Operation (-40° to 125° F)

SPECIFICATIONS

• DC output 12 volts, 200 Amps

• DC Voltage regulated at 1 Volt from no-load to full load

• Dc Voltage will reduce drastically after the load current reaches its rated current & hence protecting generator & Engine from over load

• Seperately Excited, Brushless, Provided with class 'H' Insulation, Temp. rise limited to Class F. Suitable for an ambient temperature of 40C

• D.C. Alternator for recharging battery banks. This is not an automotive style alternator because of their poor efficiency

• 200 amps DC for recharging battery banks, DC generator is the most efficient and least cost solution

• Require 5 h.p Prime mover at 1500 RPM ENGINE suitable to make a DC generator

• We can supply complete DC generator close coupled or coupling type both with water cooled and air cooled engines

LOW MAINTENANCE AND HIGH RELIABILITY

• The unique alternator design allows us to turn the engine at low speeds, thereby extending engine life.

• The voltage regulator has automatic governing at high electrical load demands the regulator automatically increases engine RPM; at low loads the engine speed is automatically decreased.

• Agrowave Power's alternator has no: brushes, slip rings, There are no alternator parts to wear.

• There are no electronic parts (diodes, etc.) nor electrical connections inside the alternator. There is nothing to short or vibrate loose inside the alternator.

• The alternator is almost impossible to damage electrically. The outputs can be shorted for minutes without damage.

• The output current is monitored by the voltage regulator through a current transducer. The voltage regulator has an adjustable current limit on the output. It is virtually impossible to overload the alternator.

• Agrowave Power's alternator should have an life of exceeding 50000 hours

• The engine is protected against: over-temperature, low oil pressure, over-speed, (OPTIONAL).

• The alternator's rotor is dynamically balanced to improve the engine's bearing life.

LOW FUEL CONSUMPTION
The Agrowave alternator has an efficiency of between 75 to 85% versus 55 to 70% for other DC alternators. Consume only 700 gm diesel in 1 hr.

HIGH AND LOW AMBIENT OPERATION

• During starting the regulator keeps the field current off. This feature coupled with the small light weight rotor provides a minimal load on the starter motor.

• For low ambient temperatures (-40° to 10° F) cold starting aids are available.

• The higher alternator efficiency allows the engine to run cooler in high ambient temperatures. The increased alternator efficiency reduces the mechanical load on the engine which then reduces the engines cooling requirement.

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