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The armature of a 6-pole, lap wound DC shunt motor takes 400 A at a speed of 350 rpm. The flux per pole is 80 mWb, the number of armature turns is 600 and 3% of the torque is lost in windage, friction and iron loss. Calculate the output torque and power in brake-horse power.

User Mellester
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Final answer:

The question involves calculating the output torque and bhp for a DC shunt motor using the electromagnetic torque formula, adjusting for mechanical losses, and then converting the torque to bhp.

Step-by-step explanation:

The question pertains to the calculation of the output torque and power in brake-horsepower (bhp) for a 6-pole, lap wound DC shunt motor. The given motor parameters include a current of 400 A, a speed of 350 rpm, flux per pole of 80 mWb, and 600 armature turns, with a loss of 3% in torque due to windage, friction, and iron losses.

To calculate the output torque (Tout), we first find the electromagnetic torque (Te) using the following formula:

  • Te = (N x I x Φ x Z x P) / (60 x 2π x A)

Where:

  • N = speed in revolutions per minute (rpm)
  • I = armature current (A)
  • Φ = flux per pole (Wb)
  • Z = total number of armature conductors
  • P = number of poles
  • A = number of parallel paths, which is equal to P for a lap wound armature

The output torque would then be:

  • Tout = Te – (3% of Te)

To calculate the output power in brake-horsepower, we use:

  • Power (bhp) = (Tout x N) / 5252

Note: The question does not provide enough details to complete the full calculations, such as the presence of a gearbox or any mechanical losses that are not mentioned. The formulae given are to be used with the given and assumed parameters for an ideal scenario.

User Nathansizemore
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