Electrical Machines and Power Utilization Quiz No. 3

What is the equivalent circuit of a real transformer?

• Only copper losses with resistance and power loss

• Magnetization current with no power loss

• Only leakage flux with no power loss

• Both copper losses and leakage flux

What is the simplified equivalent circuit of a transformer?

• Divide all Rs, Xs by a2

• Refer all quantities referred to primary side, remove the transformer

• Refer all quantities referred to secondary side, remove the transformer

• Multiply all Rs, Xs by a2

What is the purpose of the open circuit test for a transformer?

• To find the resistance of the primary side

• To find the voltage induced in the primary side

• To find the inductance of the primary side

• To find the power loss in the primary side

What is the formula for the force induced by a current carrying conductor in a magnetic field?

• F = i L B Sec (θ)

• F = i L B Sin (θ)

• F = i L B Cos (θ)

• F = i L B Tan (θ)

What is the direction of force in Fleming’s left-hand rule?

• Force (Thumb), I (index finger), B (middle finger)

• Velocity (Thumb), I (index finger), B (middle finger)

• Velocity (Thumb), B (index finger), I (middle finger)

• Force (Thumb), B (index finger), I (middle finger)

What is the formula for the induced torque in a rotating loop between curved poles?

• τind = (2/π)*φ*i

• τind = (2/π)*Φ*i

• τind = (2/π)*Φ*ω

• τind = (2/π)*φ*ω

What is the polarity in Fleming’s R H rule for the voltage induced in a conductor moving in a magnetic field?

• Thumb (I), index finger (velocity), middle finger (B)

• Thumb (velocity), index finger (B), middle finger (I)

• Thumb (B), index finger (velocity), middle finger (I)

• Thumb (I), index finger (B), middle finger (velocity)

What is the formula for the induced torque in a rotating loop between curved poles?

• Torque = r F sec (θ)

• Torque = r F tan (θ)

• Torque = r F cos (θ)

• Torque = r X F (cross product of perpendicular distance and force)

What is the formula for the voltage induced in a conductor moving in a magnetic field?

• Eind = (V X B) . L

• Eind = (V + B) . L

• Eind = (V / B) . L

• Eind = (V - B) . L

What is the formula for the impedance in the short circuit test for a transformer?

• Xeq = Zeq2 – Req2

• Psc = Isc2 Req

• Zeq = Vsc/Isc

• Psc = Vsc2 / Req