Why a generator slow down with resistive loading?

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Discussion Overview

The discussion revolves around the behavior of generators under resistive loading, specifically addressing why a generator slows down when subjected to increased resistive loads, as observed in an experiment where the frequency dropped from 50Hz to about 47Hz with unity power factor.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant notes that increasing the resistive load on a generator leads to a decrease in frequency, as observed in their experiment.
  • Another participant explains that the induced current in the generator's coil generates a force opposing the motion of the rotor, making it harder for the motor to turn as the load increases.
  • A question is raised about why similar behavior does not occur with capacitive or inductive loads, suggesting that these types of loads do not dissipate power in the same way as resistive loads do.
  • A follow-up response reiterates that capacitive and inductive loads primarily involve reactance rather than resistance, which may account for the difference in behavior under loading conditions.

Areas of Agreement / Disagreement

Participants express differing views on the effects of resistive versus reactive loading on generator performance, indicating that the discussion remains unresolved regarding the specific mechanisms at play.

Contextual Notes

The discussion does not clarify the assumptions regarding the definitions of resistive, capacitive, and inductive loads, nor does it resolve the underlying mathematical principles related to generator operation under different loading conditions.

eng_pro
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anyone here know why a generator slow down with resistive loading ?

i did an experiment and my results showed that when i loaded the generator more and more the frequency dropped from 50Hz to about 47Hz
(power factor was unity all the time)
 
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Consider the induced current in the coil as a result of the turning of the armature. [Read up on the motor effect]. This current experiences a force that is opposite in direction to the motion that induced the current. So this means that when we add a load, more has to be supplied; more current in the coil; a stronger force acts on the rotor but in a direction that opposes the original motion; thus its harder for the motor to turn.
 
but why this doesn't happen when you load using capacitive or inductive loads?
 
eng_pro said:
but why this doesn't happen when you load using capacitive or inductive loads?

because capacitative and inductive loads don't have resistance, only reactance, they don't dissipate power
 

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