ELECTRICAL ENGINEERING BITS-3

201.

A 440 V, 3-phase, 10 pole and 50 HZ synchronous motor delivering a torque of 50 N-m, delivers a power of ??
 3000W 

202.

What is the value of total electric flux coming out of a closed surface?

 Equal to total charge enclosed by the surface.

203.

______ is most commonly used for making magnetic recording tape
 Ferric oxide 

204.

Which of the following is/are the advantages of synchronous phase modifier over the shunt compensation?

 Both of these

205.

Hysteresis loss and eddy current loss are used in
 induction heating of steel 

206.

The method appropriate for heating of non ferrous materials is _______

 Indirect arc heating.

207.

Which of the following is not a necessary condition to be satisfied for synchronising an incoming alternator to an already operating alternator?

 same prime mover speed

208.

Find the number of strands of ACSR conductor for 4 layer transmission line?

 37

209.

Aluminium when adopted as a conductor material in ______ transformers, decreases the overall cost of the transformer

 small size

210.

If the gain of the critical damped system is increased it will behave as
 underdamped 

211.

A single phase, 2 KV alternator has an armature resistance of 0.8 ohms and 4.94 ohms respectively. The voltage regulation of the alternator at 100 a load 0.8 loading power factor is
 8.9% 

212.

In majority of instruments damping is provided by
 eddy currents 

213.

In a 4*4 Y bus matrix the number of non zero elements are 12. Find the sparsity of the system?

 0.25

214.

Which of the following methods is/are used for reactive or voltage compensation ______
 All of these 

215.

An instrument transformer is used to extend the range of
 induction instrument 

216.

In ______ method of staging three phase induction motors the starting voltage is not reduced.
 slip ring 

217.

For arc furnaces the voltage high current power supply is needed because ________

 Maximum secondary voltage is also limited to 275 V(line to line voltage on upon open circuit).  

218.

Which of the following is the largest conversion device?
 Synchronous machine 

219.

Find the reactance voltage when current is changed from -2A to 2A in 4 sec and self inductance is 1H?
 1 V 

220.

Direct water cooling of rotor winding presents
 greater mechanical difficulties 

221.

Electrical machines having power outputs ranging from a few kW upto approximately 250 kW may be classified as

 medium size machines

222.

Which of the following statement is true?

 A galvanometer with low resistance in series is an ammeter

223.

By which of the following methods the temperature inside arc nace can be varied ?
 By any of the above method 

224.

In an electric room heat convector the method of heating used is
 resistance heating 

225.

Apart from the skin effect the non uniformity of the current distribution is also caused by_______?
 proximity effect 

226.

Which of the following voltage regulation method is accurate ?

 ZPF method

227.

Which one of the following does not have negative temperature co-efficient ?
 Aluminium 

228.

Power for lighting in passanger coach, in a long distance electric train, is provided
 through individual generator of bogie and batteries 

230.

The band width, in a feedback amplifier.

 increases by the same amount as the gain decrease

231.

Thermonic emission occurs in
 vacuum tubes 

232.

When a synchronous motor is running at synchronous speed, the damper winding produces ??
 no torque 

233.

In thermocouples which of the following pairs is commonly used ?
 Copper-constantan 

234.

The breakdown torque of a synchronous motor varies as

 applied voltage V

235.

________increases the steady state accuracy.

 Integrator

236.

In a portable instrument, the controlling torque is provided by
 spring 

237.

For load flow studies, What are the quantities specified at load bus are ______?

 P and Q

238.

Low tension cables are generally used upto
 1000 V 

239.

When a body reflects entire radiation incident on it, then it is known as

 white body

240.

___________method can bring the locomotive to dead stop.
 Plugging braking 

241.

The two pressure coils of a single phase power factor meter have

 the same dimensions and the same number of turns

242.

A 2 pole synchronous machine is operating at 3000 rpm. Find the relation between electrical angular momentum (ωe) and mechanical angular momentum (ωm) ?
 ?e = 1/2*?m 

243.

Circuit breakers usually operate under

 transient state of short-circuit current

244.

In case of locomotives the tractive power is provided by

 double cylinder, double acting steam engine

245.

In a single phase induction motor driving a fan load, the reason for having a high resistance rotor is to achieve
 quick acceleration. 

246.

The starting torque of a D.C. motor is independent of which of the following?

 Speed

247.

In a resistance furnace the atmosphere is
 oxidising 

248.

Solid type cables are considered unreliable beyond 66 kV because
 there is a danger of breakdown of insulation due to the presence of voids 

249.

A network containing 50 buses in which 10 are the voltage control buses, 6 are the generator buses. Find the size of the Jacobian matrix?

 83*83

250.

Most sensitive galvanometer is
 spot ballistic galvanometer 

251.

If the co-efficient of adhesion on dry rails is 0.26, which of the following could be the value for wet rails ?
 0.16 

252.

Radiation from a body is proportional to ________________

 T4.

253.

The size of inter pole are small as compared to main poles. What is the reason?
 In order to not to get saturation 

254.

Which of the following medium is employed for extinction of arc in air circuit breaker ?
 air 

255.

In salient pole synchronous machine, if direct axis reactance and quadrature axis reactance is equal, then power developed due to reluctance is ____?
 zero 

256.

What type of dielectric material is used in capacitors used for fans and for power factor correction?

 Oil impregnated paper.

257.

Hydrogen has a heat transfer co-efficient _____ times that of air

 1.5

258.

Arc in a circuit behaves as

 a resistance decreasing with voltage rise across the arc

259.

The torque angle, in a synchronous motor, is the angle between _____?

 the rotating stator flux and rotor flux.

260.

In an Anderson bridge, the unknown inductance is measured in terms of
 known capacitance and resistance 

261.

The transition temperature of mercury is

 4.12°K

262.

Pressure error can be measured by which of the following ?

 Differential bellows and strain gauge

263.

The multiplier and the meter coil in a voltmeter are in
 series 

264.

Hunting in a synchronous motor takes place ??
 when load varies. 

265.

In capacitance grading of cables we use a ______ dielectric.
 composite 

266.

Substances whose specific resistance abruptly decreases at very low temperature are called
 superconductors 

267.

For which of the following 'ampere second' could be the unit ?
 Charge 

268.

Induction heating takes place in ___________
 Conducting materials may be magnetic or nonmagentic materials. 

269.

________is the property of absorbing moisture from atmosphere.
 Hygroscopicity 

270.

Direct axis reactance is defined as the ratio of ___________

 Vmax to Imin

271.

_______cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall.

 Direct

272.

Solder is an alloy of
 tin and lead 

273.

The conductors have transport phenomena of electrons due to
 electric field 

274.

Which of the following statements is correct for any closed loop system ?

 Only one of the static error co-efficients has a finite non-zero value

275.

If we increase the length of the transmission line, the charging current ________
 increases 

276.

The current due to electron flow in conduction band is the hole current in valence band.

 greater than

277.

Due to which of the following reasons copper and aluminium are not used for heating elements ?

 all of these

278.

Most of the common metals have _____ structure.
 cubic 

279.

___________ has relatively wider range of speed control.
 D.C. shunt motor 

280.

Ferranti effect can be compensated by which of the following ______
 shunt reactor 

281.

Which of the following motors is used for elevators ?
 Induction motor 

282.

In induction heating ______ is abnormally high.
 frequency 

283.

For handling greater currents induction wattmeters are used in conjunction with
 current transformers 

284.

The noise produced by a ______ cooled machine is less as the rotor moves in a medium of smaller density.
 hydrogen 

285.

If the length of a cable is doubled, its capacitance
 becomes double 

286.

The presence of earth in case of overhead lines ___________
 increase capacitance 

287.

If we increase the spacing between the phase conductors, the line capacitance ________?

 decreases

288.

For measurements on high voltage capacitors, the suitable bridge is
 Schering bridge 

289.

Stepper motor is used in _______?

 computer printers

290.

____________have maximum unbalanced forces

 Steam locomotives

291.

If the current in a capacitor leads the voltage by 80°, the loss angle of the capacitor is
 
 10°

292.

Direct arc furnaces have which of the following power factors ?

 Low, lagging

293.

The time taken by the machine to attain 0.632 of its final steady temperature rise is called

 heating time constant

294.

The metal having the lowest temperature coefficient of resistance is
 gold 

295.

Superconductors are becoming popular for use in

 generating very strong magnetic field

296.

The forced oil and air circulation method is usual one for transformers of capacities

 30 MVA upwards

297.

Which of the following happens in Kando system ?

 Single phase supply is converted into three phase system

298.

In a Weston synchronoscope, the fixed coils are connected across
 incoming alternator 

299.

The first order control system, which is well designed, has a

 large negative transfer function pole

300.

Skin effective is more in case of __________?

 Communication lines