**Last Answer :** In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

**Last Answer :** The condition for maximum efficiency for a D.C. generator is variable losses equal to constant losses.

**Description :** The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is (A) 0.25 pu (B) 0.5 pu (C) 1.0 pu (D) 1.5 pu

**Last Answer :** The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu

**Last Answer :** The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.

**Last Answer :** Series motor has got maximum self relieving property.

**Description :** The synchronous motor will develop maximum power when the load angle is?

**Last Answer :** The synchronous motor will develop maximum power when the load angle is 900.

**Description :** State maximum power transfer theorem for DC circuit.

**Last Answer :** Maximum power transfer theorem for DC circuit: The maximum power transfer theorem states that the source or a network transfers maximum power to load only when the load resistance is equal ... removed (disconnected) ii) All internal independent sources are replaced by their internal resistances.

**Last Answer :** In repulsion motor, maximum torque is developed when brush axis is at 45° electrical to the field axis.

**Last Answer :** In case the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be less than 50%.

**Last Answer :** When a D.C. series motor is connected to A.C. supply, the power factor will be low because of high inductance of field and armature circuits.

**Last Answer :** In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will remain unchanged.

**Description :** The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?

**Last Answer :** The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.

**Description :** What is the maximum value of torque angle in synchronous motor?

**Last Answer :** The maximum value of torque angle in synchronous motor is 90 degrees electrical.

**Description :** A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of 600 C/W. If the ambient temperature is 300o C ... the device will be A) 1.52 W B) 1.72 W C) 1.92W D) 2.00 W

**Last Answer :** A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of ... 300o C, then the maximum allowable power dissipation in the device will be 2.00 W

**Last Answer :** Differentially compounded D.C. motor has got maximum self loading property.

**Last Answer :** D.C. generators are normally designed for maximum efficiency around full-load.

**Description :** Describe the reason of using dc series motor for electric trains.

**Last Answer :** Electric trains require an inverse torque speed characteristics for proper operation. That is a higher torque is required at start (when speed is nil or low) and as the train picks up ... torque - speed characteristics of DC series motors match, these motors are suitable for electric trains

**Description :** A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be

**Last Answer :** A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

**Description :** A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is

**Last Answer :** A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is 36 Ohm

**Description :** In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :

**Last Answer :** In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is : 0.075

**Description :** The function of a brush and commutator arrangement in a dc motor is to (1) produce unidirectional torque (2) produce unidirectional current in the armature (3) help in changing the direction of rotation of the armature (4) reduce sparking

**Last Answer :** The function of a brush and commutator arrangement in a dc motor is to produce unidirectional torque

**Last Answer :** If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor.

**Last Answer :** For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.

**Description :** The speed of a D.C. motor can be controlled by varying 1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above

**Last Answer :** The speed of a D.C. motor can be controlled by varying 1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above

**Last Answer :** At the instant of starting when a D.C. motor is put on supply, it behaves like a low resistance circuit.

**Last Answer :** The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.

**Description :** As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit?

**Last Answer :** As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit a resistance is connected in series with armature.

**Last Answer :** The armature voltage control of D.C. motor provides constant torque drive.

**Last Answer :** The armature torque of the D.C. shunt motor is proportional to armature current.

**Last Answer :** As the load is increased the speed of D.C. shunt motor will reduce slightly.

**Last Answer :** In a differentially compounded D.C. motor, if shunt field suddenly opens the motor will first stop and then run in opposite direction as series motor.

**Last Answer :** Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be cumulatively compounded.

**Last Answer :** Sparking, is discouraged in a D.C. motor because commutator gets damaged.

**Last Answer :** D.C. Series motor is generally preferred for cranes and hoists.

**Last Answer :** Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.

**Last Answer :** If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses.

**Last Answer :** Cumulatively compounded D.C. motor will be suitable along with flywheel for intermittent light and heavy loads.

**Last Answer :** The current drawn by the armature of D.C. motor is directly proportional to the torque required.

**Last Answer :** In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to 25% of the previous value.

**Last Answer :** The speed of a D.C. series motor is inversely proportional to the armature current.

**Last Answer :** The starting resistance of a D.C. motor is generally low.

**Last Answer :** By looking at Commutator part of the motor, it can be easily confirmed that a particular motor is D.C. motor.

**Last Answer :** The armature may burn if the back e.m.f. of a D.C. motor vanishes suddenly.

**Last Answer :** In a D.C. shunt motor, speed is independent of armature current.

**Last Answer :** The speed of a D.C. shunt motor more than its full-load speed can be obtained by decreasing the field current.

**Last Answer :** If a D.C. motor is connected across the A.C. supply it will burn due to heat produced in the field winding by eddy currents.

**Description :** The type of D.C. motor used for shears and punches is?

**Last Answer :** The type of D.C. motor used for shears and punches is cumulative compound D.C. motor.

**Last Answer :** For starting a D.C. motor a starter is required because it limits the starting current to a safe value.

**Last Answer :** A D.C. series motor is that which has its field winding consisting of thick wire and less turns.

**Last Answer :** If the field of a D.C. shunt motor gets opened while motor is running the motor will attain dangerously high speed.