Select Page

Excitation system of the generator

Excitation system of generator is one among the foremost necessary topics of engineering science. DC voltage is accountable to come up with field in generator. This DC voltage may be provided to the generator singly or could also be created from the AC current created by it thorough conversion. This mechanism is named excitation system. we tend to all grasp that on the premise of excitation system, Alternators principally ar of 2 types-(1)Separately Excited system,(2) Self Excited system.

Separately and self-excited system of a generator

The basic distinction is that singly excited system have magnet Generator (PMG) for powering the automated Voltage Regulator(AVR)and there’s one Isolation electrical device for sensing the voltage for AVR and within the alternative hand for self-excited generator, there’s residual magnetism within the exciter field to initialize the voltage ramp-up method and once voltage build-up, Isolation electrical device that is chargeable for voltage sensing for AVR, begin powering the AVR likewise.

Which means in the self-excited generator, Isolation electrical device is chargeable for 2 things-(1) Sensing Voltage (2) Powering AVR once initial voltage build-up thanks to residual magnetism


  1. a singly excited system of a generator
  1. A self excited system of a generator

The self generator problem- lack of Residual Magnetism

Sometimes you will face one downside that there’s no voltage build-up within the Self-excited generator. the explanation is lack of Residual Magnetism. Then what you’ve got to try to, take away the AVR, flash the exciter field by connecting a 12V DC battery and an interference diode to the exciter field and at the moment begin the engine, if you see currently voltage is build up, then it ensures that Exciter field has been flashed with success. currently, stop the engine and take away the battery diode, connect the AVR and once more begin the engine to create certain that the generator is back operative.

Advantages of PMG Excitation Support Systems

  1. A PMG with its applicable regulator will enhance a generator’s transient performance as a result of it’ll give a continuing Ac voltage input to the automated voltage regulator(AVR) regardless of the generator’s terminal voltage.
  2. once the load on the generator is nonlinear thanks to thyristor (SCR) power provides like UPS Systems, variable speed drives etc. the load might turn out notches on the voltage severe enough to cause misfiring of the ability rectifiers during a shunt excited generator’s AVR. once this happens, the generator’s terminal voltage can become unstable.

If the generator is fitted with a PMG, the input power to the AVR is isolated from these disturbances, and no voltage un-stability can occur.

  1. A PMG is built with a magnet rotor that includes a terribly sturdy field. This eliminates the requirement for field flashing that is typically necessary with shunt sort synchronous generators.
  2. sturdy and really quick voltage build-up.

You can watch the following video or read the written tutorial below.