ELECTRICAL ENGINEERING BITS-6

201.

If the frequency is increased, then skin effect will ________?
 increases 

202.

A moving-coil permanent-magnet instrument can be used as flux-meter

 by eliminating the control springs

203.

For measuring a very high resistance we should use
 Meggar 

204.

A carbon resistor contains

 finely divided carbon black.

205.

In an open loop control system
 Output is independent of control input 

206.

Which of the following represents the pitch factor?

 Cos (a/2)

207.

For a D.C. shunt motor which of the following is incorrect?

 Unsuitable for heavy duty starting

208.

Most common form of A.C. meters met with in every day domestic and industrial installations are
 induction type single phase energy meters 

209.

Normally Z bus matrix is a ________?

 full matrix

210.

Aluminium is now most commonly employed conductor material in transmission lines than copper because _______?
 it is cheaper and lighter 

211.

Which of the following resistive materials has the lowest temperature co-efficient of resistance ?

 Nichrome

212.

A solid angle can be expressed in terms of ??
 steradians. 

213.

A 200 candle power lamp is hung 4 m above the centre of circular area of 5 m diameter. The illumination at centre of the area is ??

 12.5 lux.

214.

Under over excitation synchronous phase modifier works as ________
 shunt capacitor 

215.

The angle between induced emf and terminal voltage on no-load for a single phase alternator is

 0 degree

216.

The capacity of a crane is expressed in terms of
 tonnes 

217.

For blowers which of the following motor is preferred ?

 D.C. shunt motor

218.

———– was the first city in India to adopt electric traction.
 Bombay. 

219.

An ACSR conductor has a diameter of 2 cm has internal inductance of 0.05 mH/Km. If this ACSR is replaced with another having a diameter of 4 cm then its internal inductance is _____?

 0.05 mH/Km

220.

Flame proof motors are used in
 explosive atmospheres 

221.

Out of the following which is not a poor conductor ?
 Copper 

222.

The transient response, with feedback system,

 decays quickly

223.

The fact that current density is higher at the surface when compared to centre is known as _____
 skin effect 

224.

In DC generators brushes are used for __________?

 collecting of current without any sparkings

225.

Slip test is performed to determine _______?

 direct axis reactance and quadrature axis reactance

226.

Which of the following devices is used for conversion of co-ordinates ?
 Synchro-resolver 

227.

The relative permittivity of rubber is
 between 2 and 3 

228.

The covalent bond is formed by
 sharing of electrons between atoms 

229.

Phase margin of a system is used to specify which of the following ?

 Relative stability

230.

The emf induced in the dc generator armature winding is ____?
 AC 

232.

What is the speed of turbo alternators (Approx)

 3000 rpm

233.

In the cables, sheaths are used to

 prevent the moisture from entering the cable

234.

The increase in heat dissipation by air blasts is due to increase in

 convection

235.

The metod of heating used for non conducting materials is _____
 Dielectric heating. 

236.

An electric field of 1.92 × 103 N/c is maintained across two plates separated 0.015 m. Potential difference across plates will be

 28.8 V.

237.

Which of the following motors are best for the rolling mills ?
 D.C. motors 

238.

For power factor improvement the synchronous motor is to be _______?
 lightly loaded and over excited 

239.

For which of the following applications D.C. motors are still preferred ?

 Variable speed drive

240.

If an insulating material is operated beyond the maximum allowable temperature, its life is
 drastically reduced 

241.

A 3 layer and diameter of each strand is d, then find the total diameter of ACSR conductor?

 5d

242.

On which of the following variables heat convected depends ?
 All of these 

243.

Superconductivity is observed for

 D.C. and low frequency

244.

In India, electrification of railway track was done for the first time in which of the following years ?
 1925—1932 

245.

The size of an excavator is usually expressed in terms of
 cubic metres 

246.

Direct resistance heating is used in ________
 All of these 

247.

The speed of stator rotating magnetic field with respect to rotor rotating magnetic field?

 zero

248.

The main appliction of indirect arc furnace is to melt __________
 Non-ferous metals. 

249.

The formula ____ determines the number of electrons that can be accommodated in any level.

 2n2

250.

If skin depth is more, then skin effect is __________?

 less

251.

Which of the following buses is/are not PV buses?

 fixed shunt capacitor buses

252.

Conduit pipes are normally used to protect _____ cables.
 unsheathed cables 

253.

_________need frequent starting and stopping of electric motors,
 Lifts and hoists 

254.

Quadrilateral speed-time curve pertains to which of the following services ?

 Urban and sub-urban service

255.

To save energy during braking-----------------braking is used?
 regenerative 

256.

Which speed control method preferred for constant torque drive?

 Armature voltage control.

257.

_________can be extended to systems which are time-varying ?

 State model representatives

258.

Objectives of electrical power transmission is/are _____
 both of these 

259.

The normal voltage used in directional heating is ___________

 1.5 KV.

260.

Power transformers have rating
 above 200 kVA 

261.

A perfect black body is one that

 absorbs all incident radiations

262.

Alternating current is measured by

 induction ammeter

263.

In closed loop control system, with positive value of feedback gain the overall gain of the system will
 decrease 

264.

A control system working under unknown random actions is called
 stochastic control system 

265.

A 3- phase synchronous motor can operate over a wide range of power factors i.e. from lagging to leading power factor. This is achieved by
 changing the field excitation 

266.

A power factor meter has

 one current circuit and two pressure circuits

267.

In liquid level and electrical system analogy, voltage is considered analogous to
 head 

268.

For transmission line which one of the following relation is true?
 AD - BC = 1 

269.

A thermal protection switch can protect against

 overload

270.

In an AC. co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be
 out of phase by 90° 

271.

In a 4 bus,4×4 Y bus matrix the number of non zero elements are 12. Find the number of transmission lines?
 4 

272.

Which of the following is the definition of proportional band of a controller ?

 The range of measured variables through which the air output changes from maximum to minimum

273.

For measurement of inductance having high value, we should use

 Hay's bridge

274.

The voltage used for suburban trains in D.C. system is usually
 600 to 750 V 

275.

The coils of D.C. motor starter are wound with wire of

 manganin

276.

Which of the following alternatives will be cheaper ?
 A 100 H.P. AC. three phase motor 

277.

Armature flux is.............with respect to main field flux or main field poles?

 stationary

278.

Lap winding is prefered for which type of machines?
 high current and low voltage 

279.

Total number of crystal systems is

 7

280.

________is not a part of ball bearing ?
 Bush 

281.

For crane travel which of the following motors is normally used ?
 AC. slip ring motor 

282.

The inductance of single phase two wire line is given by ??
 4×10-7× ln(d/r') H/m 

283.

Which of the following motor has more stability ________?

 salient pole motor

284.

For accurate load flow calculations on large power systems, the best method is _____?
 N-R method 

285.

Capacitance grading of cable implies

 use of dielectrics of different permeabilities

286.

Ajax Wyatt furnace is started when
 it is filled above core level 

287.

The skin effect of conductor will increase when ____?

 resistivity decrease

288.

In an electric press mica is used
 as an insulator 

289.

Radiant heating is used for which of the following ?

 Drying of paints and varnishes

290.

The core of transformer is made up using laminations made from
 C.R.G.O Steel 

291.

The position and velocity errors of a type-2 system are
 zero, constant 

292.

When the load is above _____ a synchronous motor is found to be more economical.
 100 kW 

293.

Which of the following motors is preferred for boom hoist of a travelling crane ?

 A.C. slip ring motor

294.

_________ watt-hours per tonne km is usually the specific energy consumption for suburban services.
 50—75 

295.

With rise in temperature the resistance of semi-conductors
 decreases 

296.

The maximum power developed in cylindrical synchronous machine is occurs at a load angle of ___?

 90°

297.

What type electric drive is used in cranes?

 Multimotor.

298.

The inductance of single phase two wire line is given by _______?
 4×10-7× ln(d/r') H/m 

299.

_______is preferred for synthetic fibre mills.

 Reluctance motor

300.

For a dc machine shunt resistance and armature resistance values are _____?
 high and low