What is Zpf method?
Zero Power Factor (ZPF) for regulation of alternator: This Zero power factor (ZPF) method is used to determine the voltage regulation of synchronous generator or alternator. This method is also called Potier method.
Why is Zpf method more accurate?
In Potier Triangle or ZPF method, voltage quantities are calculated on emf basis and mmf quantities are calculated on mmf basis. Therefore, ZPF method is most accurate among all these four methods. As the armature flux is in phase with the main field flux it is additive in nature and increases the net flux.
What is Zpf load?
It is also known as the Zero Power Factor (ZPF) method. The following assumptions are made in the Potier triangle method − The armature reaction MMF is constant. The open-circuit characteristic (O.C.C.) taken on no-load accurately represents the relation between MMF and voltage under loaded conditions.
Why do we keep alternator at zero power factor?
The load current delivered by an alternator to purely inductive load is maintained constant at its rated full load value by varying excitation and by adjusting variable inductance of the inductive load. Note that, due to purely inductive load, an alternator will always operate at zero p.f. lagging.
Which method of voltage regulation is most correct?
Potier triangle method:
- This method depends on the separation of the leakage reactance of armature and its effects.
- It is used to obtain the leakage reactance and field current equivalent of armature reaction.
- It is also called a general method of voltage regulation.
- It is the most accurate method of voltage regulation.
What happens when power factor 0?
A power factor of 0 indicates that the voltage and current are 90-degrees out of phase.
What is MMF explain?
The magnetomotive force, mmf, is analogous to the electromotive force and may be considered the factor that sets up the flux. The mmf is equivalent to a number of turns of wire carrying an electric current and has units of ampere-turns.
What is the formula for voltage regulation?
The full-load voltage of 11.98 volts is calculated by substituting 0.001 (0.1 percent) and 12 volts into the calculation and then solving for the full-load voltage. Load regulation (percent) = 100 x (voltage no load — voltage full load) divided by voltage full load.
What is meant by emf?
Electromotive force (EMF) is equal to the terminal potential difference when no current flows. EMF and terminal potential difference (V) are both measured in volts, however they are not the same thing. EMF (ϵ) is the amount of energy (E) provided by the battery to each coulomb of charge (Q) passing through.
How do you calculate emf of a generator?
Derivation of EMF Equation of DC Generator (1), that for any dc generator Z, P and A are constant so that Eg ∝ Nϕ. Therefore, for a given DC generator, the induced EMF in the armature is directly proportional to the flux per pole and speed of rotation.
How to plot ZPF characteristics?
To plot ZPF characteristics only two points are required. One point is corresponding to the zero voltage and rated current that can be obtained from scc and the other at rated voltage and rated current under zpf load. This zero power factor curve appears like OCC but shifted by a factor I a X L
What is ZPFC of a generator?
Zero Power Factor Characteristic (ZPFC) of a generator is a curve of the armature terminal voltage and the field current. The machine is operated with a constantly rated armature current at synchronous speed and zero lagging power factor.
How do you draw a ZPFC circuit?
Take a point b on the ZPFC preferably well upon the knee of the curve. Draw bk equal to b’O. (b’ is the point for zero voltage, full load current). Ob’ is the short circuit excitation Fsc. Through k draw, kc parallel to Oc’ to meet O.C.C in c. Drop the perpendicular ca on to bk.
How do you construct a ZPFC from a Potier triangle?
The hypotenuse of the Potier triangle and the baseline. A similar triangle such as ckb, can construct from the Potier triangle in any other location by drawing a line kc parallel to Oc’. Take a point b on the ZPFC preferably well upon the knee of the curve.