Why is Zpf method more accurate?

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 method?

Since the load connected is purely inductive the alternator will operate at zero power factor lagging ( cos 90° ). Hence this method is also called as ‘Zero Power Factor Method (ZPF)’.

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What is the necessary condition while conducting Zpf test?

Note : In this test, there is no need to obtain number of points to obtain the curve. Only two points are enough to construct a curve called zero power factor saturation curve. This is the graph of terminal voltage against excitation when delivering full load zero power factor current.

Why MMF method is optimistic?

The field mmf (If1) required to induce the rated terminal voltage is obtained by conducting open circuit test. This method is also called an optimistic method because the voltage regulation obtained by this method is less than the actual value.

What is the primary reason for placing field on rotor in an alternator?

The primary reason for placing field winding on rotor in an alternator is insulation of high voltage is easier on stator than on rotor.

Why inductive load is used in Zpf method?

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 bad. Note that, due to purely inductive load, an alternator will always operate at zero power factor lagging.

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What is the purpose of conducting slip test?

Explanation: Slip test is used to determine the q-axis reactance. Explanation: The impedance during slip test is low so the voltage drop will be less and the current will be more. Explanation: Slip test is conducted at low terminal voltage to avoid large slip in the synchronous machines.

What is the significance of ASA method?

The ASA (American Society of Anesthesiology) score is a metric to determine if someone is healthy enough to tolerate surgery and anesthesia. The American Society of Anesthesiologists (ASA) Physical Status Classification System is a tool used in preparation for surgery to help predict risks in a given patient.

What is MMF method of voltage regulation?

MMF Method is also known as Ampere Turn Method. The MMF method replaces the effect of armature leakage reactance with an equivalent additional armature reaction MMF so that this MMF may be combined with the armature reaction MMF. …

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What are the advantages of using field winding in rotor for an alternator?

1) The current is drawn directly from fixed terminals on the stator without the use of brush contacts. 2) The insulation of stationary armature winding is easier. 3) The number of sliding contacts (slip rings) is reduced.

What are the advantages of providing the field winding on the rotor and armature winding on the stator?

What are the advantages of providing the field winding on rotor and armature winding on the stator? Explanation: If the armature winding is on the stator, only two slip rings are required which implies less losses, more efficiency and more economy. Also, stationary armature winding can be cooled more efficiently.