A  DC shunt motor has  armature resistance including brushes. The motor draws a no-load current of . The field current is constant at . Assuming that the core and rotational losses are constant and independent of the load, the current (in amperes) drawn by the motor while delivering the rated load, for the best possible efficiency, is ________ (rounded off to 2 decimal places).

A belt-driven DC shunt generator running at 300 RPM delivers 100 kW to a 200 V DC grid. It continues to run as a motor when the belt breaks, taking 10 kW from the DC grid. The armature resistance is 0.025 Ω, field resistance is 50 Ω, and brush drop is 2 V. Ignoring armature reaction, the speed of the motor is _________ RPM. (Round off 2 decimal places)

A 250 V DC shunt motor has an armature resistance of 0.2 Ω and a field resistance of 100 Ω. When the motor is operated on no-load at rated voltage. It draws an armature current of 5 A and runs at 1200 rpm. When a load is coupled to the motor, it draws total line current of 50 A at rated voltage, with a 5 % reduction in the air-gap flux due to armature reaction. Voltage drop across the brushes can be taken as 1 V per brush under all operating conditions. The speed of the motor, in rpm, under this loaded condition, is closest to:

A 220 V DC shunt motor takes 3 A at no-load. It draws 25 A when running at full-load at 1500 rpm. The armature and shunt resistances are  and  respectively. The no-load speed in rpm (round off to two decimal places) is _________.

A separately excited DC generator supplies 150 A to a 145 V DC grid. The generator is running at 800 RPM. The armature resistance of the generator is . If the speed of the generator is increased to 1000 RPM, the current in amperes supplied by the generator to the DC gird is ___________. (Give the answer up to one decimal place).

A 120 V DC shunt motor takes 2 A at no load. It takes 7 A on full load while running at 1200 rpm. The armature resistance is  and the shunt field resistance is . The no load speed, in rpm, is ___________.

A 15kW, 230V dc shunt motor has armature circuit resistance of  and field circuit resistance of . At no load and rated voltage, the motor runs at 1400rpm and the line current drawn by the motor is 5A. At full load, the motor draws a line current of 70A. Neglect armature reaction. The full load speed of the motor in rpm is_____________.

A 250V dc shunt machine has armature circuit resistance of  and field circuit resistance of . The machine is connected to 250V supply mains. The motor is operated as a generator and then as a motor separately. The line current of the machine in both the cases is 50A. The ratio of the speed as a generator to the speed as a motor is_____________.

A separately excited 300V DC shunt motor under no load runs at 900 rpm drawing an armature current of 2A. The armature resistance is  and leakage inductance is 0.01H. When loaded, the armature current is 15A. Then the speed in rpm is __________.

The dc motor, which can provide zero speed regulation at full load without any controller, is

A 220 V DC machine supplies 20A at 200 V as a generator.  The armature resistance is 0.2 ohm.  If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, then ratio of motor speed to generator speed is

A dc series motor fed from rated supply voltage is overloaded and its magnetic circuit is saturated. The torque-speed characteristic of this motor will be approximately represented by which curve of Figure?

An electric motor with ‘constant output power’ will have a torque speed characteristic in the form of a

A dc series motor is rated 230V, 1000 rpm, 80 A (refer to figure), the series field resistance is 0.11Ω, and the armature resistance is 0.14Ω.  If the flux at an armature current of 20A is 0.4 times of that under rated condition, calculate the speed at this reduced armature current of 20A.

A 240 V DC shunt motor with an armature resistance of 0.5Ω has a full load current of 40A. Find the ratio of the stalling torque to the full load torque when a resistance of 1Ω is connected in series with the armature?

The field coil of a two-pole DC series motor is made up of two identical sections. In one case (i) of two sections of the field coil are connected in series, and in another case (ii) the two sections are connected in parallel. If the motor takes the rated current in both the cases, then torque (i): torque (ii) is ….. and speed (i): speed (ii) is ….. (Neglect the effect of magnetic saturation)

Out of the following factors for a dc machine,         

(i) Inter pole                

(ii) Armature resistance

(iii) Armature leakage reactance        

(iv) Armature reaction

(v) Reduction in field current

The factors that are responsible for decrease in the terminal voltage of a shunt generator are

A differentially compounded d.c. motor with inter poles and with brushes on the neutral axis is to be driven as a generator in the same direction with the same polarity of the terminal voltage. It will then

A cumulative compounded long shunt motor is driving a load at rated torque and rated speed. If the series field in shunted by a resistance equal to the resistance of the series field, keeping the torque constant

Level compounded D.C generator is used for which of the following applications?