Alternator run at zero power factor lagging

  • #1
electricalguy
Gold Member
20
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Hello, I'm wondering if it's possible to make an alternator run at zero power factor lagging (purely inductive). I was researching this topic and apparently by shorting the leads of the alternator the output will become fully reactive. Yet I've attempted this on a small scale and the most I can get the phase between voltage and current to shift is 45°. I've increased the excitation current without a change in the phase angle. Is there something I'm missing? Is there a way I can make the alternator run purely inductive? I understand lagging power factor is demagnetizing, leading power factor is magnetizing and unity power factor is cross magnetized. Is the issues with the resistance of the stator winding?
 
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  • #2
In reality - I doubt this is possible with passive components as there will always be real losses.

If you are shorting the output - how are you measuring the voltage in taking the PF?
 
  • #3
I'm using an oscilliscope to take measurements of the line voltage and the phase current. I used a 14 gauge wire to connect the phases together. I measure the current waveform across the 14 gauge wire. I measure the difference in time between the voltage and current waveforms in milliseconds, then divide by one AC cycle in milliseconds, then multiple by 360 and this gives me the phase angle between the two in degrees.
 

1. What does it mean when an alternator runs at zero power factor lagging?

Running an alternator at zero power factor lagging means that the alternator is producing reactive power only, with no real power being delivered to the load. In this scenario, the current flowing through the system is at 90 degrees phase angle to the voltage, indicating that all the electrical power is being used to sustain the electric and magnetic fields in the circuit rather than performing any actual work.

2. Why would an alternator be run at zero power factor lagging?

An alternator might be run at zero power factor lagging primarily for testing purposes or for specific operational adjustments. For example, it may be used to simulate certain load conditions for testing the alternator's voltage regulation or to help in the commissioning process of power plants. However, in practical power generation, this condition is generally avoided as it leads to inefficient operation and increased stress on the alternator.

3. What are the effects of running an alternator at zero power factor lagging?

Running an alternator at zero power factor lagging can have several negative effects including increased heating in the alternator, higher losses, and reduced efficiency. It can also lead to voltage instability and can stress the electrical grid, potentially causing voltage regulation issues and reactive power imbalances. This operational mode is generally not sustainable for long periods in practical applications.

4. How can zero power factor lagging in an alternator be corrected?

Zero power factor lagging in an alternator can be corrected by adjusting the load or by using power factor correction devices such as capacitors or synchronous condensers. These corrections help to shift the phase angle between current and voltage towards zero, thereby improving the power factor towards unity (1) and reducing the reactive power in the system.

5. What are the implications of zero power factor for the overall power system?

The implications of zero power factor in an overall power system include increased operational costs due to inefficiencies and higher losses, potential damage to power system components, and reduced system stability. It necessitates the use of additional equipment for power factor correction, which can be costly. Maintaining a near-unity power factor is typically desired to ensure optimal, efficient, and safe operation of power systems.

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