- Single bearing with SAE disc coupling arrangements, also 2 bearing- Protection IP 23S
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- Main stator and rotor class F or H- Exciter stator and rotor class F or H
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- COMPOUND EXCITATION SYSTEM
- This system compromises:- A 3 phase compounding transformer- An auxillary winding- 3 phase rectifier bridge- A voltage regulator(optional upto 125 kva)These components are mounted at the rear of the alternator in a substanstial terminal box.
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- FUNCTION OF THE COMPOUND SYSTEM
The alternator exciter is supplied with D.C Current from the diode bridge which receives two sources of A.C> power- The first supplied by the auxillary winding in the stator being proportional to the voltage of the alternator. - The second supplied by the secondary winding of the 3 phase compounding transformer and being proportional toi the load current and P.F. The resultant current provides an excitation firld current that varies as a function of the load and P.F. to maintain the output voltage resonably constant (self regulating withought A.V.R)
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- Alternators upto 125 KVA are supplied withought a regulator, the basic compound excitation system maintaining the voltage to within +- 5% after reaching thermal stability(This is better than most countries main supply.)
Electronic AVR can be provided as optional for regulation within +-2%>The alternator voltage is adjustable by a rheostat over the range 380 to 415V, 50 Hz and 440 to 480V, 60 Hz. - Alternators above 125 KVA are supplied with a electronic voltage regulator that maintains the voltage to within +-2%- Voltage adjustment by rheostat- Power factor range 0.8 to 1.0 - including cold to hot drift - Compound "BACK-UP" auto regulation system in case of regulator failure by insertion of a rheostat.NoteAlternators can be supplied with windings giving other voltages if so required.
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| Apart from the voltage regulation characteristics the compound excitation system gives you the following advantages:- Voltage build-up from residual magnetism- Protection against low speed operation- Good motor starting, the compound system giving 2.5 to 3 times full load capacity.- Sustained short circuit current of the order of 3 times full load current.- Volts/hertz responsive - with any abdrupt in speed from the engine a corresponding reduction in voltage output releives the engine load allowing for faster re-establishment of correct speed.- Voltage dip on application of full load 0.8 P.F. in the order of 15 to 20%.- Recovery time at constant speed for full load application less than 0.5 seconds.- Over voltage limited in-case of regulator failure the voltage rise is limited to a value supplied by the compound system(adjustable).- 3 phase sensed compound system allows good operation with the unbalanced load system.- Good overload characteristics |
Bangalore, Karnataka, India
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