Electric motors of tram cars operate at a current of 112 A and a voltage of 550 V.

| August 6, 2021 | education

Electric motors of tram cars operate at a current of 112 A and a voltage of 550 V. Calculate the efficiency of the engine if, with a traction force of 3.6 kN, the speed of the tram is 12 m / s.

I = 112 A.

U = 550 V.

F = 3.6 kN = 3600 N.

V = 12 m / s.

Efficiency -?

Efficiency coefficient Efficiency shows what part of the spent work Az turned into useful Ap: Efficiency = Ap * 100% / Az.

The expended work Az is the work of the electric current in the tram engine: Az = I * U * t.

We will express the useful work Ap by the formula: Ap = F * S, where F is the traction force of the tram, S is the movement of the tram.

Efficiency = F * S * 100% / I * U * t = F * V * 100% / I * U.

We express the speed of the tram V by the formula: V = S / t.

Efficiency = 3600 N * 12 m / s * 100% / 112 A * 550 V = 70%

Answer: the tram has an efficiency of 70%.



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