Engineering, 18.03.2021 18:30 cristinanina

The following details are known about a 250 hp, 230 V, 435 rpm dc shunt motor:  Nominal full-load current = 862 A
 Insulation class = H
 Weight = 3400 kg
As an engineer, you are required to provide the derivation, consideration and assumption that
have been taken in your calculation to determine:
i. The total losses and efficiency at full load. (5 marks)
ii. The approximate shunt field exciting current if the shunt field causes 20% of the total
losses. (3 marks)
iii. The value of the armature resistance as well as the counter-emf knowing that 50% of
the total losses at full load are due to armature resistance. (5 marks)
iv. The approximate exciting current to attain a speed of 1100 rpm.

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The following details are known about a 250 hp, 230 V, 435 rpm dc shunt motor:  Nominal full-load...