Explain, in details, why it is necessary to use starting resistance?
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Q: Q1) Why is a starting resistor used in DC motor circuits?. Explain in detail.
A: As per Bartleby guidelines we are allowed to solve only three subparts, please ask the rest again.
Explain, in details, why it is necessary to use starting resistance?
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- The armature circuit of a free excited direct current motor with a nominal voltage of 600 V is fed from an adjusted direct voltage source. The excitation circuit is also powered from a regulated voltage source. It is used in an application that requires motor speed adjustment. The speed of the motor at the nominal armature voltage was measured as 1600 rpm. All losses of the motor and voltage source and the effect of armature reaction are neglected. It is accepted that the engine is not saturated.Answer the questions below.a) Draw the armature and excitation circuit of the motor and write the formulas for the equivalent circuit.b) If the load moment of the motor at the nominal armature voltage is 420 Nm, then calculate the armature current and the input power of the motor.c) If the armature voltage of the motor is kept constant at 600 V and the excitation current is decreased until the speed reaches 4000 rpm, then calculate the shaft moment. Show this working area on the M = f (W) axis.The following information is given for a 300kW, 600V, long shunt compound DC generat or, shunt field resistance is 75 ohms, armature resistance 0.01, brush resistance is 0.011 ohrms, series field resistance is 0.012 ohms and the divert or resistance of 0.036 ohms.When the machine is delivering full load; a. Draw the circuit diagrarn b. Calculate the voltage and C Power generated by the armat ure.Q5. (A) Select the correct answer for the alternatives given 1-In transformer, the load current at maximum efficiency is equal to rated load current multiplied by a) Peu Pa Pru Pi 2- When a series de motor is operated without a load, which of the following conditions occur? b) The voltage requirement increases d) The armature speeds out of control a) The armature draws excessive current c) The armature will not turn P₁ d) Peu 3- A 220V shunt motor develops a torque of216 N.m at an armature current of 40 A. The torque developed when the armature current is 20 A b)108 N.m c) 864 N.m a) 432 N.m d) 54 N.m 4-A single phase transformer has maximum efficiency at 75% of full load. Its copper loss at full load should be a) equal to core loss, b) less than core loss. c) more than core loss, d) equal to 75% of core loss 5- The efficiency of a transformer is 98% at full-load with 0.8 lagging power factor, what will be the efficiency when supplies full-load with 0.8 leading power factor? c) more…
- Speed control of a 140 V, 1.68 kW DC motor single phase thyristor full wave AC-DC It is made by the converter. AA supply voltage 220 V (rms) Is 50. In the converter It is assumed that there is no loss. The armature resistance of the DC motor is = 0.417 Q. Very a large inductance is connected in series with the motor. The motor voltage constant is = 0.0964 V/rpm. The motor can be considered as a permanent magnet DC. According to this, a) Draw the driver (converter-motor) power circuit. b) Calculate the nominal current of the motor. c) Supply voltage, supply current, converter output voltage for ignition angle a = 30 ° and Draw the waveforms for the converter output current. d) = 950 rpm and for nominal current, d1) The firing angle of the converter, d2) Effective value of supply and thyristor current, d3) Supply power factor, calculate.A250 V, dc. shunt mtor has an amature resistance of 0.5 chmand a field resistance of 250 dhm When driving a load of canstant tarque at 600 r.pm, the ammature current is 20 A If it is desired to raise the speed fram600 to 800 r.p.m, what resistance should be inserted in the shunt field circut? Assume that the magnetic circut is unsaturateda) With neat diagrams, explain the development and effects of armature reaction in an alternator. b) Briefly explain the open-circuit characteristics and short-circuit characteristics of an alternator to determine voltage regulation. c) What is regenerative braking and how does it work in electric or hybrid cars?
- L-1). The 3-phase wound-rotor induction motor has .... . a) high starting torque b) low starting current c) both "a" and "b" d) neither "a" nor "b" L-2). The 3-phase wound-rotor induction.........a) motor has a wire wound rotor b) motor's rotor can be connected to an external resistive load by way of slip rings and brushes c) motor requires more maintenance than the 3-phase squirrel-cage induction motor d) all of the above L-3). The 3-phase wound-rotor induction motor's rotor circuit's resistance should be adjusted so it is__________ during starting. a) low b) high c) either "a" or "b" d) neither "a" nor "b" L-4). Will a 3-phase wound-rotor induction motor start with no external circuit connected to its rotor leads? a) yes b) noA DC shunt motor drives a centrifugal pump at a speed of 1300 rpm when the terminal voltage and line currents are 230 V and 55 A, respectively. The armature and field resistances are 0.2 N and 1002, respectively. 1- Calculate the resistance that should Quality Control in Construction: Centrifugal Pump be added Radd n to the armature circuit to reduce the speed to 650 rpm. Radd 2- Design a starting resistance for a maximum starting current of 115.5 A in the armature circuit. Radd 4- Calculate the resistance that must be added to the armature circuit to operate the motor at the holding condition. Radd ΩELECTRICAL MACHINES 2 Describe the difference in construction operation of dc shunt, series, and compound motor. Compare the speed characteristics of dc shunt, series, and compound motor.
- A shunt generator has a full load current of 195 A at 250 V.The stray losses are 720 W and the shunt field coil resistance is 50 0.lt has a full load efficiency of 90 % Find the armature resistance.Also find the current corresponding to maximum efficiency.hi tutor this subject is all about Dc machine Please help me ASAPH. W. 4.docx H.W. 4 Division: Electronic Eng. Subject: Energy conversion I Year : Second Q1: A (250) V, d.C. shunt motor takes a line current of (20) A, Resistance of shunt field winding is (200) ohm and resistance of the armature is (0.3) ohm . Find the armature current and the back e.m.f. Q2 : Explain briefly the speed control of d.c. series motor