Electrical Question
1) give thr Function of starter ???
Ans:The device which is used to start the d.c. motor is called a starter.
The function of the starter is to limit the starting high current to a safe value.
2)When the motor is at reast the speed of the motor is zero hence back emf Eb will be ________????
Ans: zero
3)The starting current may be _______ that of full load current. ??
Ans:5 to 7 times
4)The dc shunt and compound motor is started by the how many types af starters and which?????
Ans : Two
(1)Three pointt starter and
(2)Four paint starter
5) The starter is used only for the short duration ______ time which limits the starting high current to a safe value.???
Ans:the short duration (5 to 10 sec)
6)Define the transformer???
6)Define the transformer???
Ans:A transformer is a statie electromagnetic device consisting of two or more windings which link with a common magnetic field.
- A transformer a device that transfers electric power from one circuit to another without a change of frequency.
- It can raise or lower the voltage in a circuit but with a corresponding decrease or increase current
7)when the output voltage of a transformer is higher than its input voltage, it is called _____???
Ans: step-up transformer
8) what is work of transformer??
Ans:transfers electrical energy from one circuit to another
->does so without a change of frequency
->does so by the principle of electro-magnetic induction
->has electric eircuits that are linked by a common magnetic circuit.
9)the winding In to the load from which drawn out is called which winding???
Ans:secondary-winding
10)A transformer work on the which principle???
Ans:electromagnetic induction
(13) give advantage of ward Leonard method??
(11)give one example an application of the method of speed control by the use of variable voltages to the armature of the motor whose speed controlls required.???
Ans: ward Leonard method
(12)what is ward Leonard method???
Ans:The speed control of dc motor by means of an adjustable voltage generator connected across the armature dc motor terminals of the called Ward Leonard method.
(13) give advantage of ward Leonard method??
Ans:(1)very fine speed control over the whole range from zero to normal rated speed in both directions can be obtained.
(2)Uniform acceleration can be obtained. (3)Good speed regulation
(14) list the disadvantages of ward Leonard method???
Ans:(1)This arrangement is costly due to two extra machines.
(2)overall efficiency of the system is low.
(15)give a example where use ward Leonard method for speed controlled???
Ans:paper mills, elevators etc.
16)give a type of transformer according to construction?????
17)in core type transformer winding on ____??
18) give one advantage of core type transformer???
16)give a type of transformer according to construction?????
Ans: (i) Core type and (ii) Shell type
17)in core type transformer winding on ____??
Ans:the windings surround the iron core.
18) give one advantage of core type transformer???
Ans:As the space utilization is better with stepped cores, the length of mean turn of copper is reduced and therefore copper losses and cost of copper also reduced.
19)how arrange shell type transformer winding?????
Ans:In shell type transformers, the windings are put around the central limb and the flux path is completed through two side limbs.
20)give one advantage of shell type transformer???
Ans: In this type of transformer, the coils are better braced mechanically that they are less easily displaced by the high electro-mechanical forces that frequently develop during short circuits
21) state the ideal transformer???
Ans:An ideal transformer is one which has no losses and magnetic leakage. An ideal transformer has no ohmic resistance in the windings and no leakage flux.
22)what is efficiency of ideal transformer???
Ans:100%
23)how many voltage regulation in Ideal transformer??
Ans:Zero
24)the ideal transformer consists two purly ______ coil??
Ans: inductive
26) in the auto transformer how many winding???
Ans: one
27)what is the transformation ratio of an auto-transformer ????
Ans: k=(V2/V1)=(N2/N1)=(I1/I2)
(29) Electric circuit which type of part consists????
25) The Auto Auto-transformer works on the principle of ______???
Ans: self induction
26) in the auto transformer how many winding???
Ans: one
27)what is the transformation ratio of an auto-transformer ????
Ans: k=(V2/V1)=(N2/N1)=(I1/I2)
(28)Which part consists of cores and yokes and provides path of flux in three phase transformer???
Ans:magnetic circuit
(29) Electric circuit which type of part consists????
Ans:An electric circuit consist a of LV and HV windings. The windings ara electrically separated but magnetically linked through a path of low reluctance.
(30)What is the work of dielectric circuit part in three phase transformer???
Ans:. The insulation is provided between LV and HV windings and core to LV winding.
(31)which parts consisting in Tank and accessories In the three phase transformer???
Ans:This includes cooling system, oil conservator, breather, bushings, Buchholz relay and other protective devices.
(32) what is a work of magnetic circuit in three phase transformer???
Ans:provides path of flux
(34)Give applications of Scott connection???
(35)In Scott connection the tapping how many percentage in main transformer??
(38)The VA rating of CTs is ?????
(40)give type of current transformer according to construction!!??
Ans:This includes cooling system, oil conservator, breather, bushings, Buchholz relay and other protective devices.
(32) what is a work of magnetic circuit in three phase transformer???
Ans:provides path of flux
(33)The conversion of 3-phase AC supply to two-phase AC or vice-versa can be achieved which connection???
Ans:scott connection
(34)Give applications of Scott connection???
Ans: application of Scott connection is given as below:
1) to supply power to two-phase
electric furnaces
2)to inter 3 ase and 2-phase systems
3)to supply power to a 3-phase apparatus from a two-phase source and vice-versa
(35)In Scott connection the tapping how many percentage in main transformer??
Ans:50%
(36)In the scott connection the 86.6% tapping in which transformer????
Ans:teaser transformer
(37)What is the current transformer????
Ans:A CT is a device for the transformation of current from a higher values to a lower values that are suitable for measurement of the relay operation.
(38)The VA rating of CTs is ?????
Ans:very small
(39)primary winding of current transformer have how many ternes???
Ans:The primary winding of the CT consists of one or few turns of thick wire
(40)give type of current transformer according to construction!!??
Ans:According to the construction, the CTs can be classified into two ways
(i) Bar primary CTs or single turn CT wound type
(ii) Wound type CT
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