When can the voltage regulation of an alternator be negative?
Explanation: Voltage regulation for an alternator operating at leading power factor is negative due to magnetizing nature of armature reaction. Explanation: Field flux gets aided by the armature reaction leading to higher Vt.
For which type of load negative voltage regulation of an alternator can be possible?
For lagging and unity p.f. conditions there is always drop in the terminal voltage hence regulation values are always positive. While for leading capacitive load conditions, the terminal voltage increases as load current increases. Hence regulation is negative in such cases.
Under which condition voltage regulation of transformer is negative?
Explanation: The sign -ve arises in the voltage regulation calculations when, the load connected to the transformer is leading in the nature. The only condition when we’ll get negative voltage regulation when second term is higher than first term. 6.
Is negative voltage regulation possible?
Negative voltage regulation can only occur with leading power factor loads; however, not all leading loads will cause negative voltage regulation. Negative voltage regulation means the voltage increases with the load. This is a very undesirable condition because it can lead to an unstable condition.
What is voltage regulation of alternator list the methods?
For large alternators, the three indirect methods are used to determine the voltage regulation they are as follows: Synchronous Impedance Method or EMF method. Ampere-turn method or MMF method of Voltage Regulation. Zero Power Factor method or Potier Method.
Why is voltage regulation important in alternator?
A knowledge of voltage regulation at different power factors are usually essential because it shows how closely a machine will maintain its voltage under the various conditions of load. This knowledge is also important from the point of voltage control, parallel operation and protection of the alternators.
What is the condition for zero voltage regulation for alternator and why?
Thus zero Voltage Regulation is achieved by leading load of power factor xe2 / ze2 and if we increase the power factor of load beyond this value then Voltage Regulation will become negative. Negative Voltage Regulation means that Secondary Terminal Voltage V2 is more than the no load generated EMF E2.
When the load on an alternator is varied?
Whenever the load on the alternator is varied, the terminal voltage will also vary. This variation in terminal voltage is mainly due to three reasons: Voltage drop due to armature resistance IRa, Voltage drop due to armature leakage reactance IXL and Voltage drop due to armature reaction.
Which of the following voltage regulation may be zero or negative?
Voltage regulation is zero or negative value on the leading power factor load or capacitive load as the voltage rises due to increase in load. 03․ For which of the following loads, armature reaction is magnetizing in nature?
Under which conditions can voltage regulation be positive or negative?
At unity and lagging power factor loads, the terminal voltage is always less than the induced EMF and the voltage regulation is positive. At higher leading loads, the terminal voltage is greater than the induced EMF and the voltage regulation is negative.
What is the condition for minimum voltage regulation?
In a transformer minimum voltage regulation occurs when the power factor of the load is leading. The voltage regulation of the transformer is zero at a leading power factor load such as a capacitive load.
What is the condition for maximum voltage regulation?
The regulation is maximum when the load power factor angle is equal to the impedance angle of the transformer. i.e., Equation (1.58) shows the power factor of the load at which voltage regulation is maximum.
Why sometimes the voltage regulation of a transformer is positive and sometimes negative?
If the transformer supplies a very low lagging power factor, large secondary currents will flow resulting in poor voltage regulation due to greater voltage drops in the winding. … Therefore positive regulation produces a voltage drop in the winding while a negative regulation produces a voltage rise in the winding.