Question

A $3-\varphi$, 16 pole alternator has a star-connected winding with 144 slots and 10 conductors per slot. The flux per pole is 0.03 Wb and is sinusoidally distributed. If the speed is 375 rpm then the value of the line emf generated will be

• A. 2850 V
• B. 2750 V
• C. 2658 V
• D. 2557 V

Answer 1

The correct option is C 2658 V

$375=\frac{120\ast f}{16}\Rightarrow =50Hz$
Slots per pole = $\frac{144}{16}=9$
Slot per pole per phase, $m=\frac{144}{16\times 3}=3$
$\beta =\frac{{180}^o}{slotperpole}={20}^o$
$k_d=\frac{sin\frac{m\beta }{2}}{msin\frac{m\beta }{2}}\Rightarrow k_d=\frac{0.5}{3\times 0.174}=0.96$
Z = number of conductors in series per phase $=\frac{144\times 10}{3}=480$
$E_{line}=\sqrt{3}\times 4.44f{N}_{ph}{\varphi }_m{k}_d$

$=\sqrt{3}\times 4.44\times 0.96\times 0.03\times \frac{480}{2}\times 50$
$=2657.76V$