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Consider the following statements: In the above figure, the curves pertain to the DC motor A. Speed vs Armature current characteristic of a DC shunt motor B. Torque vs Armature current characteristic of a DC shunt motor C. Speed vs Armature current characteristic of a DC series motor D. Torque vs Armature current characteristic of a DC series motor
In an alternator, the armature winding is kept stationary while the field winding is kept rotating for the following reasons: 1. Armature handles very large current and high voltage 2. Armature fabrication, involving deep slots to accommodate large coils, is easy if armature is kept stationary 3. It is easier to cool the stator than the rotor Which of the above reasons are correct?
Which of the following statements are correct for an ideal constant voltage source? 1. Its output voltage remains absolutely constant whatever the change in load current. 2. It possesses zero internal resistance so that internal voltage drop in the source is zero. 3. Output voltage is provided by the source would remain constant irrespective of the amount of current drawn from it. 4. Output voltage provided by the source varies with the amount of current drawn from it.
Which of the following statements are true? a. As load increases armature current decreases, regardless of excitation. b. For under and over excited motors, power factor tends to approach zero with increase in load c. With normal excitation when load is increased, change in armature current is greater than in power factor which tends to become increasingly leading. d. Both with under and over excitation, change in power factor is greater than in armature current with increase in load.
Consider the following statements with respect to synchronous machines. State whether these statements are true or false. (a) Armature reaction is demagnetising when a generating machine supplies zero power factor lagging current. (b) Armature reaction is magnetising when a generating machine supplies zero power factor leading current. (c) Armature reaction is mostly cross-magnetising, though it has a small demagnetising component, when a generating machine supplies unity power factor current.
Consider the relational schema given below, where eId of the relation dependent is a foreign key referring to empId of the relation employee. Assume that every employee has at least one associated dependent in the dependent relation. Employee (empId, empName, empAge) Dependent(depId, eId, depName, depAge) Consider the following relational algebra query: ΠempId(employee)-ΠempId (employee⋈(empId = eID)∧(empAge ≤ depAge)dependent) The above query evaluates to the set of empIds of employees whose age is greater than that of
When an electric current coil of a wattmeter is connected to the electric current path R and the voltage coil is connected between the electric current R path and the neutral side of the balanced three phase supply, it shows 10 kW. The line voltage along the phase sequence RYB is 400 V. The current drawn by the current path is 54 A. What is the new reading of the wattmeter if the voltage coil is connected between the lines B and the Y paths, even if the electric current coil is continuously present in the line R?
Consider the following statements: In case of helical gears, teeth are cut at an angle to the axis of rotation of the gears. 1) Helix angle introduces another ratio called axial contact ratio. 2) Transverse contact ratio is equal to axial contact ratio in helical gears. 3) Large transverse contact ratio does not allow multiple teeth to share the load. 4) Large axial contact ratio will cause larger axial force component Which of the above statements are correct?
The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be
What is the value of β in a current gain with resistive load amplifier if Vf = 12V and VO = 12V?