Range of tachometer generator : 0:4000 rpm
accuracy: 0.4% of full scale
output: 18 V
ideal rating: rpm
Since 6V corresponds to a speed of 1000 rpm, 18 V of output would correspond to mean speed of 3000 rpm (unitary method).
Therefore, the ideal value of speed is 3000 rpm.
To calculate the minimum and maximum values of speed, we have to deduct and add the deviation to the ideal value of speed.
Deviation = 0.4 % of full scale reading, ie., 0.4 % of 4000.
Deviation = 16 rpm
Therefore, maximum speed = 3000 + 16 = 3016 rpm.
Minimum speed = 3000-16 = 2984 rpm.