The Distribution Factor is also known as the Breadth Factor or Belt factor or Spread factor. It is defined as the ratio of the actual voltage obtained to the possible voltage if all the coils of a polar group were concentrated in a single slot. It is denoted by K.
2. Distribution factor is defined as the ratio of
Actual voltage to Possible voltage
Possible Voltage to Actual Voltage
Actual Power to Possible Power
Possible Power to Actual Power
Answer.1. Actual voltage to Possible voltage
Explanation
The Distribution Factor is also known as the Breadth Factor or Belt factor or Spread factor. It is defined as the ratio of the actual voltage obtained to the possible voltage if all the coils of a polar group were concentrated in a single slot. It is denoted by K.
3. Calculate the distribution factor for a single layer 18 slots 2-pole three-phase stator winding
5. The armature of a single phase alternator is completely wound with T single turn coils distributed uniformly. The induced voltage in each turn is 2V (RMS). The emf of the whole winding is
2 T volts
1.414 T volts
1.314 T volts
1.273T volts
Answer.4. 1.273T volts
Explanation
For a uniformly distributed 1-phase alternator, the distribution factor,
7. In alternators, the distribution factor for the given number of phases is dependent only on the
Number of turns per coil
Supply voltage
Number of distributed slots under a given pole
Type of the windings
Answer.3. Number of distributed slots under a given pole
Explanation
The Distribution Factor is also known as the Breadth Factor or Belt factor or Spread factor.
In alternators, the distribution factor for the given number of phases is dependent only on the number of distributed slots under a given pole.
It is defined as the ratio of the actual voltage obtained to the possible voltage if all the coils of a polar group were concentrated in a single slot.
It is denoted by Kd
Kd = A / B
Where,
A is the vector sum of induced EMF
B is the arithmetic sum of induced EM
In a concentrated winding, each phase of a coil is concentrated in a single slot.
The individual coil voltages induced are in phase with each other.
These voltages must be added arithmetically.
In order to determine the induced voltage per phase, a given coil voltage is multiplied by the number of series-connected coils per phase.
In actual practice, in each phase, coils are not concentrated in a single slot.
They are distributed in a number of slots in space to form a polar group under each pole.
The voltages induced in coil sides are not in phase, but they differ by an angle β which is known as the angular displacement of the slots.
The phasor sum of the individual coil voltages is equal to the total voltage induced in any phase of the coil
8. A 3-phase alternator is wound with 60° phase-spread armature windings and develops 300kVA. If the armature is reconnected utilizing all the coils for single-phase operation with a phase spread of 180 degrees, the new rating of the machine is
Pitch factor is defined as the ratio of the induced emf per coil when the winding is short-pitched to the induced emf per coil when the winding is full pitched.
It is given by Kp = cos (α/2)
Where α is the short pitch or chording angle
Distribution factor:
It is defined as the ratio induced emf with distributed winding to the induced emf with a concentrated winding.
It is given by ${k_d} = \frac{{\sin \frac{{mγ }}{2}}}{{m\sin \frac{γ }{2}\;}}$
Pitch factor Kp = cos α /2 = cos (30°/2) = cos 15°
Winding factor Kw = (1/ (3√2) sin 15°) × cos 15° = $\frac{1}{{3\sqrt2}}\cot \left( {{{15}^0}} \right)$
12. A winding with only one slot per pole per phase is called _______
Concentrated winding
Distributed winding
Both 1 and 2
None of the above
Answer.1. Concentrated winding
Explanation
A winding with only one slot per pole per phase is called a concentrated winding. In this type of winding, the emf generated/phase is equal to the arithmetic sum of the individual coil EMFs in that phase.
However, if the coils/phase are distributed over several slots in space (distributed winding), the EMFs in the coils are not in phase (i.e. phase difference is not zero) but are displaced from each by the slot angle α. (The angular displacement in electrical agrees between the adjacent slots is called slot angle).
13. A winding with several slots in space is called
Concentrated winding
Distributed winding
Both 1 and 2
None of the above
Answer.2. Distributed winding
Explanation
If the coils/phase are distributed over several slots in space (distributed winding), the EMFs in the coils are not in phase (i.e. phase difference is not zero) but are displaced from each by the slot angle α. (The angular displacement in electrical agrees between the adjacent slots is called slot angle).
A winding with only one slot per pole per phase is called a concentrated winding. In this type of winding, the emf generated/phase is equal to the arithmetic sum of the individual coil EMFs in that phase.