Answer / rvg

PMG is Permanent magnet generator. The alternator generaly
uses a self excited generator and converts its voltage to DC
and then applies to alternator armature windings.
this kind of alternators are named as brushless modern
alternators.

Answer / s.madhavan

The answer above is partially correct. All AC alternators
presently manufactured are brush less type with built in
AVRs ( Automatic Voltage regultors ) Normally AVR get feed
back from load for its regulation. If the loads connected
have excessive harmonic content, feed back to AVR get
distorted and hence regulation gets affected. To avoid this
a PMG is mounted on the alternator itself which feed DC to
armature winding without reference to the load

Answer / nagendra

To completely eliminate the malfuntion of AVRs(that are
being fed from generator terminals through excitation
transformer) due to load fluctuations on the alternator
Permanant magnet generator is a solution.PMG wil feed to
the AVR giving AC output,which wil be converted into DC and
wil be fed to the field winding of the AC exciter of the
main generator(but not to main generator field).Finally AVR
controls the exciter output (by varying its field
voltage).Exciter output wil be directly connected to the
main generator field through rotating uncontrolled
rectifiers.

Answer / santosh kumar verma

PMG is Permanent magnet generator mounted at the end of the alternator shaft. The alternator generally uses a self excited generator and converts its voltage to DC and then applies to Exciter armature winding through AVR. Generated voltage from this exciter fed to Main alternator field after proper rectification (Through rotary bridge rectifier) & alternator get excited, This kind of alternators are named as brushless modern alternators.
A synchronous generator whose AVR is taking its input power from the generator is termed a shunt excited generator. If the generator’s terminal voltage is reduced as is seen with transient voltage dips upon the application of significant block loading or motor starting, the input voltage to the AVR is reduced by the percentage of transient voltage dip. This reduction in input voltage to the AVR reduces its ability to force swift recovery of the generator’s terminal voltage, and may well impact the generator’s ability to start relatively large motor loads.
Meanwhile the PMG is used for stability of Alternator voltage, better regulation to make reliable source.
Please note in such system A complete brushless alternator built with the below combination
PMG + Exciter + Main Alternator

Answer / bcn

feed back reference of alternator

Answer / sanjeet swarnakar

both the answer is right


please tell me ur email ID
my email ID is sanjeet.swarnakar@gmail.com

Answer / basudeb sarker

The PMG is rotated by the prime mover and cuts the field
windings of the pilot exciter, which induces high frequency
1ph A.C in these windings. This is the starting point of
generating a voltage
This voltage is fed to the AVR where it is regulated and
rectified and its D.C output fed to the main exciter field
windings.

Answer / nishant chowdhary

answer 2 is much practical and correct.

Answer / asif raza

please anybody tell me why the PMG o/p supply frequency is
taken more then ac generator frequency. plzzz tell me the
reason.

Answer / sameer.ugar

please anybody tell me why the PMG o/p supply frequency is
taken more then ac generator frequency. plzzz tell me the
reason.

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