Question

A commutator with a diameter of 50 cm rotates at 600 rpm. For a brush width of 2 cm, the time of commutation is,

• A. 2.47 msec
• B. 1.78 msec
• C. 1.273 msec
• D. 0.718 msec

Answer 1

The correct option is C 1.273 msec

Rotation speed = 600 rpm

$N=\frac{600}{60}=10$ rev / sec
Peripheral velocity of commutator,

$V_P=\pi DN$
$=\pi \times 50\times 10cm/sec$

As we know, $V_P\times t_c=$ Brush width
$\therefore$ Time of commutation, $t_c=\frac{2}{\pi \times 50\times 10}=1.273$ msec