Iron losses in a D.C. machine are independent of variations in?

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

Related questions

Last Answer : In a D.C. generator, the iron losses mainly take place in armature rotor.

Description : In DC motor iron losses are occurred in?

Last Answer : In DC motor iron losses are occurred in the armature.

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

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

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

Last Answer : The total losses in a well designed D.C. generator of 10 kW will be nearly 500 W.

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

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

Last Answer : In case of D.C. machines, mechanical losses are primary function of speed.

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.

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 : 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 : 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 : 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 : Brushes of DC machine are made up of ?

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

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 : State the losses in secondary distribution system.

Last Answer : The losses in secondary distribution system: a) Technical losses: 1. Due to poor voltage 2. Due to unbalance load 3. Due poor quality of transformer & its components 4. Due to poor quality ... of induction type of energy meter. 3. Lack of administration. 4. Energy theft 5. Unmetered supply

Description : Explain the “mitigation of power theft” and “faulty meter replacement” for energy conservation techniques to reduce commercial losses.

Last Answer : Energy conservation techniques to reduce commercial losses:  1. Mitigation of Power Theft: Power theft being the most important issue which all of the service providing utilities ... agricultural sector. Prepaid meters may prove effective measures against unauthorized abstraction of energy.

Description : Explain following techniques related to energy conservation in transmission and distribution system. (i) By balancing phase currents (ii) Variable technical losses (I2R losses).

Last Answer : (i) Balancing Phase currents: Proper (healthy balanced) three phase loads always draw equal currents in all lines but single phase loads in the 3 phase 4 wire system or loads connected between two ... . 11) Minimize I2R losses. 12) Balance the load currents. 13) Regulate the system voltages.

Description : The friction losses in Real Transformers are :  (A) 0% (B) 5% (C) 25% (D) 50%

Description : Which of the following can reduce the Eddy current losses? A) By making the core of a stack of plates electrically insulated from each other B) By making the core of solid block C) By increasing the applied voltage  D) None of these

Last Answer : Which of the following can reduce the Eddy current losses? A) By making the core of a stack of plates electrically insulated from each other B) By making the core of solid block C) By increasing the applied voltage  D) None of these

Description : Reduction in core losses and increase in permeability are obtained with transformer employing?

Last Answer : Reduction in core losses and increase in permeability are obtained with transformer employing core built-up of laminations of cold rolled grain oriented steel.

Description : Losses which occur in rotating electric machines and do not occur in transformers are?

Last Answer : Friction losses windage losses

Description : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?

Last Answer : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.

Description : Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is?

Last Answer : Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is approximately equal to 1.

Description : In a synchronous motor which losses varies with load?

Last Answer : In a synchronous motor, copper losses varies with load.

Description : What are the types of power losses in inductor?

Last Answer : Copper losses, Eddy current loss, and hysteresis loss are the types of power losses in inductor.

Description : In synchronous motor, does the winding losses vary with load?

Last Answer : No, in the synchronous motor the winding losses do not vary with load.

Description : Explain the on state losses in power BJT.

Last Answer : On state losses in power BJT: Transistor have four types of losses one is turn on state losses second is turn off state losses third is turn on switching losses and fourth is turn ... ON = VCE sat x IC With increasing collector current collector to emitter saturation voltage increases.

Description : Iron losses in a D.C. machine are independent of variations in (a) speed (b) load (c) voltage (d) speed and voltage

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.

Description : Do you iron your clothes?

Last Answer : Lika hail no!

Description : Which Foods are Good Sources of Iron?

Last Answer : Google, Google and Google some more. I did this for iron rich foods just 2 days ago and there is a plethora of great information. Also, do what your Dr. told you, but I do find that slow release iron supplements (like slow-fe) are far easier on your system.

Description : How to Clean Wrought Iron

Last Answer : How to Clean Wrought Iron Items made from wrought iron can look beautiful, grand and elegant, but it only takes a few years for them to make your house looking like a haunted house more than an elegant ... of time. Chances are, you will just have to paint over the stains to cover them up completely.

Description : How to Iron Jeans ?

Last Answer : How to Iron Jeans There's nothing like a pair of thoroughly wrinkled jeans to make one look unkempt and unhygienic. Learn how to iron your jeans properly, which will only make you look good, but it will ... can last for a week. You can also opt to iron your jeans once a week, after laundering.

Description : How to Increase Iron in Your Diet ?

Last Answer : How to Increase Iron in Your Diet Iron is essential for the production of hemoglobin and myoglobin. These are important proteins needed in transporting oxygen throughout the body. Iron also improves ... iron sources in your diet to prevent acquiring diseases associated with low levels of iron.

Description : How to Iron a Shirt ?

Last Answer : How to Iron a Shirt If you want to learn how to iron your own clothes, shirts are a good starting point. Shirts are typically the easiest to iron, and can be done perfectly in a short time. Here' ... fabric and beads should have a towel on top for an indirect contact, with the iron on a low setting.

Description : How to Clean a Steam Iron ?

Last Answer : How to Clean a Steam Iron Ironing clothes with a steam iron is a relatively easy task, but if the appliance is not properly maintained, it will cause more harm than good. Steam irons become clogged ... ironing will not be a tedious task. Remember these steps and keep your steam iron in tiptop shape.

Description : What to look for when choosing an iron?

Last Answer : What to look for when choosing an iron? Today, the purchase of an iron is not a big problem. This piece of household appliances is presented in a wide range of stores. Each manufacturer tries to ... its presence increases the cost of the iron by an average of 10%. Good luck with your choice!

Description : Select insulating materials for following parts : (i) Insulation between heating element and base plate of electric iron. (ii) Insulation used over copper or aluminium conductor used for making coils. (iii) Transformer bushings. (iv) Insulation between transmission line and pole.

Last Answer : Parts Insulating Materials  Insulation between heating element and base plate of electric iron. Mica Insulation used over copper or aluminium conductor used for making coils.  ... Transformer bushings Porcelain  Insulation between transmission line and pole. Porcelain

Description : Which is the best conductor: silver, carbon, or iron?

Last Answer : Silver is the best conductor. Carbon is the semiconductor. Iron have less conductance as compared to silver.

Description : At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is :  (A) 7000 W (B) 6000 W (C) 8000 W (D) 4000 W

Last Answer : At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is : 6000 W

Description : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be  (1) unaffected (2) decreased (3) increased (4) either decreased or increased depending on the direction of the DC field

Last Answer : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be either decreased or increased depending on the direction of the DC field

Description : The iron alloy, ALNICO is mainly used to make ________ A) Temporary magnets B) Permanent magnets C) Transmission lines D) None of these

Last Answer : The iron alloy, ALNICO is mainly used to make Permanent magnets