The tram speed is 72 km / h, the traction force of the electric motor is 1.2 kN. What is the efficiency of an electric motor

| May 8, 2021 | education

The tram speed is 72 km / h, the traction force of the electric motor is 1.2 kN. What is the efficiency of an electric motor if the voltage in the overhead line is 600 V and the current in the motor is 50 A?

V = 72 km / h = 20 m / s.

Ft = 1.2 kN = 1200 N.

U = 600 V.

I = 50 A.

Efficiency -?

The efficiency is determined by the formula: efficiency = Apol * 100% / Azat, where Apol is useful work, Azat is work expended.

The useful work of the Apol tram can be found by the formula: Apol = Ft * V * t, where Ft is the engine thrust force, V is the tram speed, t is the tram travel time.

We find the spent work Azat according to the Joule-Lenz law: Azat = U * I * t, where U is the current voltage, I is the current strength, t is the time of passage of the current.

The formula for determining the efficiency will have the form: efficiency = Ft * V * t * 100% / U * I * t = Ft * V * 100% / U * I.

Efficiency = 1200 N * 20 m / s * 100% / 600 V * 50 A = 80%.

Answer: The efficiency of the tram is efficiency = 80%.



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