Electrical Machines (EE4003) In-class questions

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Electrical Machines (EE4003) In-class questions

Q1

A three-phase, four-pole, 50-Hz, 200-kVA, 1100-V, star-connected induction motor has the following design data:

Specific magnetic loading               =       0.6 T

Specific electric loading                  =       25000 A-conductors/m

Full load leakage impedance drop    =      10% of rated voltage

Slot fill factor                                 =      0.7

Current density of conductors          =      5 A/mm2

A square pole design is used.  The winding is full-pitched and uniformly wound.

(a) Deduce the formula for determining the output coefficient G.

(b) Determine the diameter of the air gap and the axial core length.

(c) If there are 48 slots in the stator and all conductors in the same phase are connected in series, estimate the number of turns per phase and the total cross-sectional area of each slot.

(Note: Slot fill factor = cross-sectional area of all conductors per slot/ total cross-sectional area per slot)