Electrical Machines

Question Determine the dynamic load of you vehicle: • Calculate the inertia of your vehicle. What are the assumptions that you made to find the inertia? What is the acceleration required for your drive? Justify it Calculate the required dynamic torque and power for the selected acceleration. Calculate the total torque and power required. Justify the operating conditions of your design (is the machine properly sized?) Select a DC machine for your drive from a catalogue: Justify the selection of your machine Specify your machine technical characteristics Do you need a gearbox? Does it impact your design? Redo the calculations if required Sanity check: how do your electric motor (power, torque) compare to a commercial vehicle? Justify the differences/similarities

(b) A two-legged core made of steel is shown below, together with its magnetization curve. The winding (Ni) on the left leg of the core has 600 turns, and the winding (N2)on the right leg of the core has 200 turns. The coils are wound in the directions shown in the figure. The dimensions of the core are as shown, and the currents are i 0.5 Aand i = 1.00 A. (i) How much total flux dot is produced in the core by the specified currents? (ii) What is the relative permeability 4, of the core under these conditions?

Explain in brief the principle of AC synchronous and induction motors.

3.17. The one-line diagram of a three-phase power system is as shown in Figure3.36. The transformer reactance is 20 percent on a base of 100 MVA, 23/115kV and the line impedance is Z = j66.125N. The load at bus 2 is Sz = 184.8MW +j6.6 Mvar, and at bus 3 is S3 = 0 MW +j20 Mvar. It is required tohold the voltage at bus 3 at 115/0° kV. Working in per-unit, determine thevoltage at buses 2 and 1.

1 Mark x 5 = 5 Marks] A 50-kW, 460-V, 50-Hz, two-pole, three phase induction motor has a slip of 5 % when operating a full-load conditions. At full-load conditions, the friction and windage losses are 700 W, and the core losses are 600 W. Find the following values for full-load conditions: a) The shaft speed (nm). b) The output power (Pout). c) The load torque (tload). d) The induced torque (Tind). e) The rotor frequency (f;).

2: Obtain the Thevenin equivalent of the following circuit and find the current I, in the circuit.

2. A Y-connected 100 hp 440 V, 8-pole (class B) induction motor was tested to determine its equivalent circuit parameters. Test results are given below: No load test: 440 V, 60 Hz, 40 A, 4.2 kW Blocked rotor test: 100 V, 60 Hz, 140 A, 8 kW DC test: 8 V, 48 A a) Determine the parameters of the equivalent circuit. b) The motor is connected to a 3-phase 440 V, 60 Hz supply and runs at 870 rpm.Determine the input current, input power, air gap power, rotor copper losses,converted power, and efficiency.

Single phase 10kVA 2300/230V two winding transformer Connected as autotransformer to stepup the voltage from 2300-2530. a. Draw the schematic of the autotransformer showing the voltages and currents at full load. b. Find the kVA rating of the auto transformer.

Considering the circuit below, with a buzzer () „Motor (M) and lamp ( a) Explain what will happen if both K2 and K1 are on (closed). b) Explain what will happen if K2 is off (open) and K1 is on(closed). c) Explain what will happen if both K2 and K1 are off (opened).

Justify your answer for the following questions: DC motors use permanent magnets to construct a static magnetic field. If a motor consumes 184 kW of power but only produces 231 HP at the shaft, its current operating efficiency is answer to the nearest one.% (1 Horsepower = 745.7 Watts). Round your c) Induction motors use commutators to transmit current to the rotor, thus producing rotor magnetic field.a A live reading of a motor indicates that it is consuming 16.4 kVA with a Power Factor of 0.76. You also know the current operating efficiency of the motor is 89%. What is the instantaneous power output of the motor? (1 Horsepower = 745.7 Watts).