The rate of movement of charge through any conductor is known as
Horse power is the unit of
Three resistance of values 8 ohms, 12 ohms and 24 ohms are connected in parallel across12 volts supply, the total resistance of the circuit will be
The sure test of electrification is
The suspectance (b) of a branch can be determined by
106.The accuracy of M.C. instrument as compared to M.I. instruments is –
Which of the following advantage, the dynamometer watt meter has ?
In case of two phase supply the electrical displacement of the winding is –
Synchronising (parallel operation) of three phase alternator as compared to single phase alternator is –
The controlling torque can be produced by –
The generator which gives d.c. supply to the rotor is called –
Under no load running condition the angle between induced voltage and supply voltage willbe –
One foot angular is equal to –
For welding of sheets which type of welding is recommended –
The spot welding machine can be used for welding sheets of thickness –
In which of the following places 70 MW gas turbine power plant being operated as base load plant ?
The solar or photo voltaic cell converts
The efficiency of solar cell is about
The main source (s) of production of biogas is / are
Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of oxygen (anaerobically), primarily consisting of methane and carbon dioxide. Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste.
Which of the following plants will take least time in starting from cold conditions to full-load operation ?
Shunt capacitors in a substation
The unit of transmission loss coefficient is
The permissible variation of frequency in power system is
Generators for base load plants are usually designed for maximum efficiency around
Two -insulator discs of identical capacitance value C makes up a string for a 22 kV, 50 Hz,single-phase overhead line insulation system. If the pin to earth capacitance is also C, then the string efficiency is
The knowledge of diversity factor helps in computing
The load duration curve for a power station is as shown in the given figure. The reserve capacity in the plant at 70% capacity factor is
Flat rate tariff can be charged on the basis of
The low power factor of an industrial plant is uneconomical for
Consider the following materials for line conductors :
1. Hard drawn copper
2. Cadmium copper
4. Galvanised steel
The correct sequence of the descending order of their electrical conductivities is
Effect of temperature rise in overhead lines is to
Stringing chart is useful
The number of discs in a string of insulators for 400 kV ac overhead transmission line lies in therange of
Transmission lines are transposed to
For transmission line which one of the following relation is true ?
Sheaths are used in cables to
As compared to ac transmission dc transmission is free from
Plug setting of an electromagnetic relay can be altered by varying
The operating characteristic of a distance relay in the R-X plane is shown in the figure. It represents operating characteristic of a
Undervoltage relays are mainly used for
Signal mixing transformers are used for
The current ICBO flows in the
In a common collector amplifier the voltage gain is
When a transistor is used in switching mode then what is the turn on time ?
In the pnp transistor circuit shown in the given figure, the transistor is in saturation with values of Vbe = 0.7 V,V ce(sat) = 0.3 V and b min = 20.The value of IC will be
A silicon transistor with VBE sat = 0.8V,b dc = 100and VCE sat= 0.2 V is used in the circuit shown in given figure.What is the minimum value of RC for which transistor is in saturation ?
For a trans conductance amplifier, input and output resistances are respectively
The FET shown is a
Thermal runaway is not encountered in FETs because
The applied voltage of a certain transformer is increased by 75%; while the frequency of theapplied voltage is reduced by 25%. The maximum core flux density will :
On which of the following factors does hysteresis loss depend ?
(1) Flux density
(3) Thickness of laminations
Select the correct answer using the code given below:
The total iron loss in a transformer core at normal flux density was measured at 25 Hz and at 50Hz and was found to be 250 W and 800 W respectively. The hysteresis loss at Hz would be
according to the data flux density is constant.
now iron loss Pi=Ph1+Pe1
1. ph1 + pe1=250
2. 2ph1+ 4pe1=800
solving we get ph2= 200w
Open-circuit test in a transformer is performed with
The full-load copper loss and iron loss of a transformer are 6,400 W and 500 W,respectively. The above copper loss and iron loss at half load will be :
If P1 and P2 be the iron and copper losses of transformer at full-load and the maximum efficiency is at 75% of the full-load, then what is the ratio of P1 and P2?
A 500 kVA transformer has constant loss of 500 W and copper losses at full load are 2,000 W.Then at what load, is the efficiency maximum ?
The concentric windings are used in core type transformers with ______ winding placed next to the core.
Scott-connected transformers can convert
(a) 3 to 2 phases (b) 2 to 3 phase
(c) 2 to 4 phases (d) 3 to 4 phase
From the above correct answer is
For the parallel operation of transformers, which of the following conditions must be satisfied ?
Two transformers operating in parallel will share the load depending upon their
The saving in copper achieved by converting ordinary two winding transformer into an auto transformeris governed by the
Assertion (A): Norton's theorem is applied to a network for which no equivalent Thevenin's
Reason (R): Norton's Theorem enables one to calculate quickly current and voltage in a
particular branch of interest in a complicated network.
Superposition theorem is not applicable for
Consider the circuits A and B given below: For what values respectively of l and R, the circuit B is equivalent to circuit A ?
The output resistance of the circuit at port AB is
The current is given by
If the steady -state current at t = ¥ is 12A, then the value of a and initial value of current will be
A cable has inductance of 0.22 mH per km and capacitance of 0.202mF per km. The surge impedance of the cable is
A high resistance cannot be measured by simple ammeter-voltmeter principle because
Consider the following statements regarding the balanced ac bridge shown in the given figure for
measurement of a coil Z1
1. Z2 = Z2 in series with L2 Z3 = R3, Z4 = R4
2. Z2 = R2, Z3 = R3 and Z4 = R4 in parallel with L4
3. Z2 = R2, Z3 and Z4 = R4, in series with L4
4. Z2 = R in parallel with L2, = Z3 = R3 and Z4 = L4
Which of these statements are correct ?
In an Anderson bridge, the unknown inductance is measured in term of known
Which one of the following is represented by the circuit shown below
Which of the following bridges can be used for inductance measurement ?
1. Maxwell bridge
2. Hay's bridge
3. Wein bridge
4. Wheatstone bridge
Select the correct answer using the code given below
An imperfect capacitor is represented by a capacitance C in parallel with a resistance R. The
value of the dissipation factor tan d is
For the bridge shown in the given figure. At the balance the values of Rx, Cx and Qx will be
Which of the following is used to measure the leakage resistance of a capacitor
Wagner Earth devices in ac bridge circuits are used for
A bridge circuit works at a frequency of 2 kHz. Which detector can be used for detecting the null conditions in the bridge
The current drawn by a 220 V dc motor of armature resistance 0.5W and back emf 200 Vis
A d.c. series motor is accidentally connected to single-phase a.c. supply. The torque produced will be
For a given torque reducing the diverter resistance of a d.c. series motor
The dummy coils in d.c. machines are useful to
The speed of a d.c. shunt motor may be varied by varying
1. Field current
2. Supply voltage
3. Armature circuit
Select the correct answer using the codes given below:
Consider the following statements In a dc machine, iron loss occurs in
1. armature core
3. pole cores
4. pole shoes
Which of these statements are correct
The armature resistance of a 6-pole lap wound d.c. machine is . If the armature is
rewound as a wave-winding, what is the armature resistance
Match List-I (Characteristic) with List-II n (Relation) and select the correct answer using
the code given below the lists:
For a constant supply voltage, what are the effects of inserting a series resistance in the field circuit of a d.c. shunt motor, on its speed and torque
If the armature current is increased to double its previous value, and the time of commutation is halved, how will the reactance voltage vary
189.Neglecting all losses, how is the developed torque (T) of a dc separately excited motor, operating under constant terminal voltage related to its output power (P)
A dc shunt generator is supplying a load of 1.8 kW at 200 V. Its armature and field resistances are 0.4W and 200W respectively. What is the generated emf
Torque developed by the armature of a dc motor is proportional to which one of the following
What are slot wedges in a dc machine, made of
The graph shown below represents which characteristic of a d.c. shunt generator
The armature MMF waveform of a dc machine is
For a P-pole machine, the relation between electrical and mechanical degrees is
The maximum efficiency occurs in a separately excited d.c. generator when the terminal voltageis 220 V and the induced emf is 240 V, the stray losses, if the armature resistance is 0.2 W , will be
Which one of the following statements is correct for the ideal field excitation during starting in caseof shunt and compound motors
The air-gap between the yoke and armature in a dc motor is kept small
A 4-pole dc generator is running at 1500 rpm. The frequency of current in the armature winding is
The overall efficiency of a dc shunt generator is maximum when its variable loss equals
When a 'pumped storage' power plant is operated in conjunction with a steam power plant