# In a four-pole D.C. machine?

In a four-pole D.C. machine alternate poles are north and south.

## Related questions

Last Answer : In a D.C. machine stray loss is the sum of iron loss and mechanical loss.

Last Answer : To avoid formation of grooves in the commutator of a D.C. machine the brushes of opposite polarity should track each other.

Last Answer : Open circuited armature coil of a D.C. machine is identified by the scarring of the commutator segment to which open circuited coil is connected and indicated by a spark completely around the commutator.

Last Answer : In case of D.C. machine winding, number of commutator segments is equal to number of armature coils.

Last Answer : Iron losses in a D.C. machine are independent of variations in load.

Description : The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is  (1) 1000V (2) 100V (3) 600V (4) 10,000V

Last Answer : The induced emf in the armature of a lap -wound four -pole dc machine having 100 armature conductors rotating at 600 rpm and with 1 Wb flux per pole is 1000V

Description : A 36 slot, 4 -pole, dc machine has a simplex lap winding with two conductors per slot. The back pitch and front pitch adopted could be respectively

Last Answer : A 36 slot, 4 -pole, dc machine has a simplex lap winding with two conductors per slot. The back pitch and front pitch adopted could be respectively 19,17

Description : Why poles of dc machine are laminated?

Last Answer : Poles of DC machines are laminated to reduce the eddy current losses in the poles.

Last Answer : Copper losses,iron losses,variable losses , constant losees

Description : Explain concept of back emf in DC machine. State how it governs armature current.

Last Answer : Back emf: When the armature of DC machine rotates under the influence of driving torque, the armature conductors move in the magnetic field and cut it and hence emf is induced in them. The ... flow of armature current i.e. it automatically changes the armature current to meet load requirements.

Description : A 200 V DC machine supplies 20 A 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%, the ratio of motor speed to generator speed is

Last Answer : A 200 V DC machine supplies 20 A 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%, the ratio of motor speed to generator speed is 0.87

Description : Aluminium is not used as winding wire for the armature of a dc machine because  (1) aluminium has low resistivity (2) a large winding space is taken by aluminium conductors and creates ... ) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper

Last Answer : Aluminium is not used as winding wire for the armature of a dc machine because  (2) a large winding space is taken by aluminium conductors and creates jointing problems (3) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper

Description : In a dc machine, interpoles are used to  (1) neutralize the effect of armature reaction in the interpolar region (2) generate more induced emf in the armature (3) avoid interference of the armature flux with the main -field flux (4) reduce the demagnetizing effect of armature reaction

Last Answer : In a dc machine, interpoles are used to neutralize the effect of armature reaction in the interpolar region

Description : The magnetic neutral plane shifts in a dc machine (A) in the direction of motion of motor (B) in the direction of motion of generator (C) due to increase in the field flux (D) cause reduction of flash over between commutator segments

Last Answer : The magnetic neutral plane shifts in a dc machine in the direction of motion of generator

Description : What is the percentage of stray losses in DC machine?

Last Answer : Percentage of stray losses in DC machine is about 1 % .

Description : Brushes of DC machine are made up of ?

Last Answer : Brushes of DC machine are made up of carbon.

Last Answer : Iron loss, copper loss and mechanical losses these are the losses in DC machine.

Description : Eddy currents are induced in the pole shoes of a D.C. machine due to?

Last Answer : Eddy currents are induced in the pole shoes of a D.C. machine due to relative rotation between field and armature.

Last Answer : In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilised is called armature.

Description : The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole)  (A) has q -axis current only (B) has d -axis current only (C) has both d and q axis currents (D) cannot be divided between q and d axis currents

Last Answer : The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) has d -axis current only

Last Answer : In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be 8.

Last Answer : In D.C. generators the pole shoes are fastened to the pole core by counter sunk screws.

Description : What is the function of the roll forming machine ?

Last Answer : It is much easier to make croissants and other dinner rolls with a roll forming machine, than it is to roll the croissants by hand. The primary function, therefore, is to take the mixed dough and to thin it, then fold it, to prepare the dough for baking.

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Description : How to Repair a Sewing Machine

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Description : How to Thread a Sewing Machine

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Description : How to Clean a Washing Machine

Last Answer : How to Clean a Washing Machine You need a washing machine to clean all your clothes and have them smelling clean, so have you ever thought about what it takes to keep the actual machine clean? ... of the washing machine dry. Repeat cleaning the front load washing machine at least once a month.

Description : 10 Benefits of climber machine

Last Answer : 10 Benefits of climber machine The climber machine is tall, slim machine pinched away in the corner of the gym. Maybe you've seen someone on it apparently with his personal trainer in ferry. It's ... that will give more strength to the arms and legs and will increase the strength of the body too.

Description : How to choose a rowing machine and how to use it?

Last Answer : Many people know that it is easy to calculate rowing athletes against the background of other people by a special article. The beauty of their figure is formed during rowing sessions, which provide an ... times for 10 minutes with 10-minute breaks, this will be tantamount to one 30-minute lesson.

Description : Capsule coffee machine. What are the advantages?

Last Answer : Having a coffee maker in the house helps us to easily cheer up and brighten up the beginning of the upcoming day in the morning, especially if the weather is unpleasant. A cup of hot ... favor is the fact that the profile of this manufacturer is precisely capsule coffee makers and coffee capsules.

Description : How to choose a washing machine?

Last Answer : How to choose a washing machine? When choosing a washing machine, first of all, you need to think about the future location of its placement. According to what space you have, choose: ... occurs using a fairly simple method - the machine includes an additional rinse cycle. Enjoy the shopping!

Description : Explain the basic parts of a slotting machine with neat sketch.

Last Answer : Base or Bed The base is rigidly built to take up all the cutting forces and the entire load of the machine. The top of the bed is accurately finished to provide guideways on which ... return mechanism. 2. Variable speed reversible motor drive mechanism. 3. Hydraulic drive mechanism.

Description : Write down the basic parts of a lathe machine with their proper functions.

Last Answer : Important Parts of Lathe and their Functions 1. Bed It is the main body of the machine. All main components are bolted on it. It is usually made by cast iron due to its high compressive strength and ... carriage on bed. 12. Spindle: It is the main part of lathe which holds and rotates the chuck.

Description : Write down the steps involved for internal thread cutting on lathe machine.

Last Answer : Steps involved for internal thread cutting on lathe machine  1) Hole is first bored to the root diameter of the thread. 2) Tool is fixed on the tool post or on the boring bar adjusted the angle of ... the start. 10) Keep going until the calculated depth of cut has been reached on the top slide.

Description : Types of slotting machine

Last Answer : 1. Puncher slotter 2. Precision slotter 3. Production slotter  Working Principle of Slotting machine:- The slotting machine is a reciprocating machine tool in which, The vertical slide holding the cutting ... longitudinal and cross feeds, a rotary feed motion is also provided in the work table.

Description : Define Feed and speed in shaping machine

Last Answer : 1) Feed: Feed (S) is the relative movement of the work or tool in a direction perpendicular to the axis of reciprocation of the ram per double stroke. It is expressed in mm per stroke. 2) Speed: ... speed is the speed at which the metal is removed by the cutting tool in a period of one minute.

Description : Electrical specifications with values for washing machine.

Last Answer : 1. Type: Top loading / Front loading type 2. Capacity range: 6kg to 15kg 3. Motor Used: Induction motor 4. Input voltage: 100V- 240V 5. Power: in 1200W / Output power 100–400W{can go upto 1000W) 6. Efficiency: Max efficiency 31% 7. Wattage: 2.100-2.400 W 8. Current: 13A 9. Frequency: 50hz

Description : function of exposer in photocopier machine.

Last Answer : A bright lamp illuminates the original document, and the whitws areas of the original document reflect the light onto the surface of the photoconductive drum. The areas of the drum that are exposed ... discharge to the ground. The areas of the drum not exposed to light remains negatively charged

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Description : UNIT 1 fundamentals of AC rotating machine Contents 1.1 Introduction 1.2 Advantages 1.3 Parts of AC machines 1.4 Synchronous speed 1.5 AC winding 1.6 Winding factor ( ... alternator or generator 1.9 Numericals 1.10 Harmonic 1.11 Slot harmonics 1.12 Harmonics minimization

Last Answer : 1.2 Advantages: In practices most of alternator have rotating magnetic field type construction with stationary armature due to following reason. The generation level of AC voltage may be in the range ... at high speed. Only two Slip rings are required to excited the field by AC supply.

Description : In 8085 microprocessor, how many T-states does OPCODE FETCH machine cycle normally require (i.e., when HOLD and WAIT signals are NOT forced)? A) 4 to 6 B) 3 to 8 C) 2 to 3 D) 8 to 12

Last Answer : In 8085 microprocessor, how many T-states does OPCODE FETCH machine cycle normally require (i.e., when HOLD and WAIT signals are NOT forced)? A) 4 to 6 B) 3 to 8 C) 2 to 3 D) 8 to 12

Description : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as  (1) synchronous motor (2) synchronous generator (3) asynchronous motor (4) asynchronous generator

Last Answer : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as synchronous generator

Description : The 'Equal area criterion' for the determination of transient stability of a synchronous machine connected to an infinite bus  (1) ignores line as well as synchronous machine resistance ... consideration the possibility of machine losing synchronism after it has survived during the first swing.

Description : During a disturbance on a synchronous machine, the rotor swings form A to B before finally setting down to steady state at point C on the power angle curve. The speed of the machine during oscillation is synchronous at point(s)

Last Answer : During a disturbance on a synchronous machine, the rotor swings form A to B before finally setting down to steady state at point C on the power angle curve. The speed of the machine during oscillation is synchronous at point(s) only at C

Description : Torque angle for the synchronous machine is the angle between (A) stator magnetic field and rotor magnetic field (B) stator magnetic field and net magnetic field in the air gap (C) rotor magnetic field and net magnetic field in the air gap (D) excitation voltage and impedance voltage drop

Last Answer : Torque angle for the synchronous machine is the angle between rotor magnetic field and net magnetic field in the air gap

Last Answer : The wattage of motor for driving domestic sewing machine will be around 100 to 150 W.

Last Answer : To limit the operating temperature an electrical machine should have proper current rating.

Last Answer : Synchronsizing power of a synchronous machine is inversely proportional to the synchronous reactance.

Last Answer : A synchronous machine with low value of short-circuit ratio has lower stability limit.

Description : If we change the excitation of synchronous machine will it affect on power factor?

Last Answer : Yes, If we change the excitation of synchronous machine it will affect on power factor. If the synchronous motor is overexcited then it will have leading power factor and if the motor is underexcited then it will have lagging power factor.