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The smallest change in a measured variable to which an instrument will respond is
Two bulbs marked 200 wtt-250 volts and 100 watt-250 volts are joined in series to 250 volts supply. Power consumed in circuit is
Hysteresis losses in a d.c. machine are proportional to
Torque/ weight ratio of an instrument indicates
Series reactors are used to
What is the range for a 3(1/2)digit digital voltmeter ?
........ is the region of a transistor which has highest conductivity.
Two coils have self-inductances of 0.09 H and 0.01 H and mutual inductance of 0.015 H. The coefficient of coupling between coils is
Two resistances R1 and R2 give combined resistance of 4.5 ohms when in series and 1 ohm when in parallel. The resistance are
In a star-connected system without neutral grounding, zero-sequence currents are
Sensitivity of a voltmeter is given as
If one of the central springs of a Permanent Magnet Moving Coil ammeter is broken then when connected it will read
The positive sequence current of a transmission line is :
The teeth in the armature of a dc machine are sometimes skewed. This is done to reduce
When a line-to-ground fault occurs, the current in the faulted phase is 100 A. The zero-sequence current in this case will be :
Resistance across A and B in the circuit shown below is
In a CRT the highest positive potential is given to
the purpose of the synchronising control in a CRO is to
Power factor of an inductive circuit can be improved by connecting a capacitor to it in
In measurements made using a Q-meter impedance elements should preferably be connected in
Wagner Eearth devices in ac bridge circuits are used for
Wagner’s earth devices are used in ac bridge circuits to eliminate the effect of earth capacitance.
When the supply terminals of a dc shunt motor are interchanged
The current of a single-phase load drawn from a 3-phase system has:
The minimum number of wattmeter (s) required to measure 3-phase 3-wire balanced or unbalance power is
The voltage coil of a single phase house energy meter
Which one of the following methods decreases the error due to connections in a dynamometer type wattmeter ?
If the positive-, negative-and zero-sequence reactances of an element of a power system are 0.3, 0.3 and 0.8 pu respectively, then the element would be a
A separately excited dc generator is feeding a dc shunt motor. If the load torque on the motor is halved approximately
A manganin swamp resistance is connected in series with a moving coil ammeter consisting of a milliameeter and a suitable shunt in order of
If starter is not used dc motor for starting, it will draw a starting current which
The deflecting torque of a moving iron instrument is
If all the sequence voltages at the fault point in a power system are equal, then the fault is a
A set of independent current measurements taken by four observers was recorded as : 117.02 mA, 117.11 mA, 117.08 mA and 117.03 mA. What is the range of error ?
Two coils having equal resistances but different inductances are connected in series. The time constant of the series combination is the
The zero-sequence circuit of the three-phase transformer shown in the figure is
The accuracy of Kelvin’s double bridge for the measurement of low resistance is high because the bridge
The octal equivalent of decimal 98 is
Steady state stability of a power system is improved by
The transistor is usually encapsuled in –
An alternating e.m.f. is applied to a pure inductance such that inductive reactance is 10 W.
If the frequency of a.c. is doubled, the reactance will become
The positive-sequence current for a L-L fault of a 2kV system is 1,400 A, and corresponding current for a L-L-G fault is 2,220 A.
The zero-sequence impedance of the system is
An RLC resonant circuit has a resonance frequency of 1.5 MHz and a bandwidth of 10
kHz. If C = 150 pF, then the effective resistance of the circuit will be
Match List I with List II and select the correct answer using the codes given below the lists:
For the same voltage drop, increasing the voltage of a distributor n-times.
A single – Phase, 200 V alternator has armature resistance and reactance of 0.8W and 4.94W respectively. The voltage regulation of the alternator at 100 A load at 0.8 leading power factor is
The insulation coordination for UHV lines (above 500 kV) is done base on
A SCIM having a rated slip of 4% on full load has a starting torque the same as full-load torque.The starting current is
Lightning is a huge spark caused by electrical discharge taking place between
A network N ' is dual of network N if
Which of the following is usually not the generating voltage ?
Post-deflection is required in CRO, if input signal frequency is
In a resistance loaded, RC coupled amplifier the D.C. component is blocked by –
An higher scale ammeter is used to measure too low current. The measurement would have low
Dominating harmonics in IM is
A 3-Phase star-connected symmetrical load consumes P watts of power from a balance supply. If the same load is connected in delta to the same supply , the power consumption will be
Dead zone of an instrument is
Which of the following components of a D.C. generator plays vital role for providing direct current of a D.C. generator ?
What is the slope of the line due to1/jW factor in magnitude part of Bode plot?
For the circuit shown in fig. the meter will read
The ratio of starting torque to full load torque is least in case of—
An indicating instrument is more sensitive if its torque to weight ratio is
When a capacitor was connected to the terminal of an ohmmeter the pointer indicated a low resistance initially and then slowly came to infinity position. This shows that the capacitor is
Impulse ratios of insulators and lightning arresters should be
For complete protection of a 3-phase transmission line we require
Hopkinson’s test is conducted at—
The difference between the indicated value and the true value of a quantity is
Which of the following is the fastest switching device?
Consider the protection system shown in the figure. The circuit breakers numbered from 1 to
7 are of identical type. A single line to ground fault with zero fault impedance occurs at the
midpoint of the line (at point F), but circuit breaker 4 fails to operate ("stuck breaker"). If the relays
are coordinated correctly, a valid sequence of circuit breaker operation is
In an Anderson bridge, the unknown inductance is measured in term of known
Mho relay is usually employed for the protection of
To measure 5 volts. If one selects a 0 – 100 V range voltmeter which is accurate within + 1%,then the error in this measurement may be up to
The full-load copper loss and iron loss of a transformer are 6,400 W and 5,000 W respectively. The copper loss and iron loss at half load will be, respectively
Curve A and B represent the properties for materials which have
Vibration galvanometers, tuneable amplifiers and head phones are used in
If the readings of the two wattmeters are equal and positive in two wattmeter method, the load pf in a balanced 3-phase 3-wire circuit will be
The most serious consequence of a major uncleared short-circuit fault could be
A distribution transformer is selected on the basis of
Under the condition of resonance in R-L-C series circuit, the pf of the circuit is
Consider the following statements associated with an energy meter.
1. It is an integrating type instrument.
2. It is an induction type instrument.
3. It uses a permanent magnet for rotation of aluminium disc.
4. it employs a high control torque.
Which of these statements are correct ?
In a.c. circuit, the power is consumed only in
Which portion of the transmission system is more prone to faults ?
An ideal dc generator has a regulation of ____ per cent.
The maximum power that can be distributed in the load in the circuit shown in
Which one of the following is the main cause of creeping in the induction type energy meters ?
The errors introduced by an instrument fall in which category ?
Which portion of the power system is least prone to faults ?
At resonant frequency an R-L-C circuit draws maximum current due to the reason that
Schering bridge can be used to measure which one of the following ?
If an induction type energy meter runs fast, it can be slowed down by
The teeth in the armature of a dc machine are sometimes skewed. This is done to reduce
The maximum short-circuit current occurs in the case of:
The capacitance and loss angle of a given capacitor specimen are best measured by
The most commonly used input signal (s) in control system is/are
Wattless current is possible, only in
For a fault at the terminals of synchronous generator, the fault current is maximum for a