Recent questions tagged load

Description : Explain MCB and ELCB with connection diagram supplying single phase load. 

Last Answer : OR OR Explanation: * MCB provides short circuit protection. * MCB provides overload protection * ELCB provides earth fault protection. * MCB is in series with ... occurs, the ELCB cuts off the power within the time of 0.1 sec. automatically to protect the personnel. 

Description : Single-phase mid-point controlled rectifier with RL load

Last Answer : Single-phase mid-point controlled rectifier with RL load : The circuit configuration of single-phase midpoint controlled rectifier is shown in the figure. During positive half-cycle of ... some part of next positive half-cycle of voltage with reversed polarity can appear across load.

Description : Class A Load Commutation

Last Answer : Class A: Load Commutation: The class A or load commutation (also called self-commutation or resonant commutation) is employed in thyristor circuits supplied from DC source. The commutating components include ... biased. Thus the zero-current and reverse-bias cause the thyristor to turn-off. 

Description : Single-phase Midpoint controlled rectifier with Resistive load

Last Answer : Single-phase Midpoint controlled rectifier with Resistive load:  1) During positive half cycle of AC supply, a is positive with respect to b , this makes T1 forward biased and T2 is reverse ... voltage reverses the polarity and T2 is turned off. The operation is as shown in waveforms.

Description : Define for polyphase circuit (i) Balanced load (ii) Unbalanced load. Draw one example circuit for each type of load.

Last Answer : i) Balanced Load: Balanced three phase load is defined as star or delta connection of three equal impedances having equal real parts and equal imaginary parts.  Example circuit:  ii) ... satisfy the condition of balance, then it is called as unbalanced load.  Example circuit:

Description : Compare base load plant with peak load plant. 

Last Answer : Sr.No. Points Base load plant Peak load plant  1 Definition The power plant which supplies base load of load curve is known as base load plant The power ... power station   Small capacity storage hydro, pumped storage hydro, gas, diesel power station. 

Last Answer : 1. Connected Load: It is the sum of load of all equipment's connected to supply system which are in use or not in use of each consumer. OR   The sum of connected load of all consumers ... is the maximum load which a consumer uses at a particular time period out of his total connected load. 

Description : Why does the speed of a DC shunt motor decrease as the load increases?

Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

Description : Define the terms: i) Tariff ii) Fuel surcharge iii) Electricity Duty iv) Connected load

Last Answer : i) Tariff: The rate at which a consumer is charged for the consumption of electricity is called as tariff. OR The amount of money framed by the supplier for the supply of electrical energy ... is the total wattage of all appliances which are used by the consumer on his sanctioned connection. 

Description : Define the following terms related to tariff: (i) Connected load (ii) Unit consumed (iii) Fixed charges (iv) Electricity Tax 

Last Answer : (i) Connected load  It is the sum of the power ratings (Watts or kW or MW) of all devices and machines existing (installed) in the premises of consumer. It is used to decide the ... a percentage of the total electricity bill which includes all amounts that go to the electricity supply agency. 

Description : Define the following: i) Residential load ii) Industrial load

Last Answer : i) Residential load: The electrical load which is used in residential installation is called as residential load. E.g. incandescent lamp, florescent tube, fan ,5A socket &15A socket etc.   ii ... 3-ph any type of motor, electric furnace ,oven,welding transformer and any power load etc. 

Description : Compare base load plant with peak load plant on any two points.

Last Answer : Points Base load plant Peak load plant Definition The power plant which supplies base load of load curve is known as base load plant  The power plant which supplies ... ,thermal,nuclear power station Small capacity storage hydro,pumped storage hydro,gas,diesel power station.

Description : State why nuclear power plants are used as base load plants and diesel power plants as a peak load plant. 

Last Answer : 1. Because of following points Nuclear power plant used as base load power plant:-  1. Nuclear power plants is very economical for producing bulk amount of electric power 2. Nuclear power plant is reliable ... . The plants can be put on load easily. 4. Diesel engines take less time to make OFF.

Description : Explain with diagram load duration curve.

Last Answer : It is drawn from load curve. It is graph of load (MW/KW) arranged in descending order of magnitude with respect to time. 

Description : Define each of following terms: i) Connected load ii) Spinning reserve. 

Last Answer : i) Connected Load :- It is the sum of load of all equipment connected to supply system which are in use or not in use of each consumer. ii) Spinning Reserve:- It is reserved generating capacity in operation and connected to bus bar and ready to take a load.

Description : Define balanced 3 phase load.

Last Answer : Balanced 3 phase Load: Balanced three phase load is defined as star or delta connection of three equal impedances having equal real parts and equal imaginary parts. It takes same current of equal magnitude and equal phase angle.

Description : Define balanced and unbalanced load in three phase circuit.

Last Answer : Balanced Load: When all the imedances of 3 phases are equal in magnitude and of same nature then load is said to be balanced.  Unbalanced Load: When all the imedances of 3 phases are not equal in magnitude and of different nature then load is said to be unbalanced.

Description : Define load and line regulation.

Last Answer : 1. Load regulation : The load regulation indicates how much the load voltage changes when the load current changes. The load regulation is defined as:  % Load regulation = (VNL-VFL) / VFL *100  ... the power supply. A well-regulated power supply can have a line regulation of less than 0.1%.  

Description : An SSB transmitter produces a peak-to-peak voltage of 200 V across a 100 Ω antenna load. What is the Peak Envelope Power? A) 49.98 W B) 79.98 W C) 99.96 W D) 199.93 W

Last Answer : An SSB transmitter produces a peak-to-peak voltage of 200 V across a 100 Ω antenna load. What is the Peak Envelope Power? A) 49.98 W B) 79.98 W C) 99.96 W D) 199.93 W

Description : A zener voltage regulator has load requirements of 12 V and 2 A. The zener diode minimum current requirement is 0.2 A. The minimum voltage at input is 24 V. What is the required value of series resistance with source? A) 5.45 Ω B) 6 Ω C) 7.2 Ω D) 6.38 Ω  

Last Answer : A zener voltage regulator has load requirements of 12 V and 2 A. The zener diode minimum current requirement is 0.2 A. The minimum voltage at input is 24 V. What is the required value of series resistance with source? A) 5.45 Ω B) 6 Ω C) 7.2 Ω D) 6.38 Ω  

Description : A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is

Last Answer : A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is 0.707

Description : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be

Last Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

Description : In load flow Study, a PV bus is treated as a PQ bus when

Last Answer : Voltage at the bus becomes high 

Description : The following formula is correct:  (A) Load factor=Average load for a period/ Peak load for the same period  (B) Load factor=Average load for a period x Peak load for the same period  (C) Load factor=Average load for a period + Peak load for the same period  (D) All of the above

Last Answer : The following formula is correct: (A) Load factor=Average load for a period/ Peak load for the same period (B) Load factor=Average load for a period x Peak load for the same period (C) Load factor=Average load for a period + Peak load for the same period (D) All of the above

Description : Load flow studies involve solving simultaneous  (1) linear algebraic equations. (3) linear differential equations. (2) non-linear algebraic equations. (4) non-linear differential equations.

Last Answer : Load flow studies involve solving simultaneous non-linear algebraic equations.

Description : Load factor is the  (1) Ratio of maximum load on the station to sum of consumer's maximum load.  (2) Ratio of average demand to maximum demand.  (3) Factor used for increasing load.  (4) Reciprocal of (1).

Last Answer : Load factor is the Ratio of average demand to maximum demand. 

Description : A transformer has negative voltage regulation when its load power factor is   (1) Zero (2) Unity (3) Leading (4) Lagging

Last Answer : 0

Description : The load duration curve for unity load factor will be of  (1) Rectangular shape (2) Triangular shape (3) L -shape (4) I -shape

Last Answer : The load duration curve for unity load factor will be of Rectangular shape

Description : A 3-phase voltage source inverter operates in 180° conduction mode with a star connected resistive load. If input dc voltage is 100 V, then the peak to peak output line voltage is :

Last Answer : A 3-phase voltage source inverter operates in 180° conduction mode with a star connected resistive load. If input dc voltage is 100 V, then the peak to peak output line voltage is : 200 V

Description : A transformer operates 24 hours day at full -load. It's full -load efficiency is :  (A) equal all day efficiency (B) more than all -day efficiency (C) less than all -day efficiency (D) equal to maximum efficiency

Last Answer : A transformer operates 24 hours day at full -load. It's full -load efficiency is : equal all day efficiency 

Description : Generally in a power system network, the load is represented as a :  (A) Constant power in both load flow study and in stability study  (B) Constant power in load flow study and constant ... impedance in load flow study  (D) Constant impedance in both load flow study and in stability study

Last Answer : Generally in a power system network, the load is represented as a : Constant power in load flow study and constant impedance in stability study 

Description : In tuned power lines, on load :  (A) the receiving end voltage is numerically equal to the sending end voltage  (B) the receiving end current is numerically equal to the sending end current  (C) there is no voltage drop  (D) all the above

Last Answer : In tuned power lines, on load :  (A) the receiving end voltage is numerically equal to the sending end voltage  (B) the receiving end current is numerically equal to the sending end current  (C) there is no voltage drop  (D) all the above

Description : In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load  (A) The armature current increases and the power factor decreases  (B) The armature ... but is lagging  (D) The armature current decreases and the power factor increases and is leading

Last Answer : In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load The armature current decreases and the power factor increases and is leading

Description : Load compensation in power systems is a process to :  (A) Maintain better voltage profile (B) Increase short circuit capacity of the system (C) Generate required harmonics for loads like arc furnaces (D) Compensate for the line reactance

Last Answer : Load compensation in power systems is a process to : Maintain better voltage profile

Description : In order to have a lower cost of electrical energy generation the load factor  (1) and the diversity factor should be low (2) should be low but the diversity factor should be high (3) should be high but the diversity factor should be low (4) and the diversity factor both should be high

Last Answer : In order to have a lower cost of electrical energy generation the load factor and the diversity factor both should be high

Description : A 3 -phase, fully controlled, converter is feeding power into a DC load at a constant current of 150 A, the rms value of the current flowing through each thyristor of the converter is

Last Answer : Please show the solution for this question

Description : Power station having Load factor = 70%, capacity factor = 50%, used factor = 60%, maximum demand = 20MW then annual energy production is  (1) 122.8 GWh (2) 198.55 GWh (3) 128.2 GWh (4) 188.82 GWh

Last Answer : Power station having Load factor = 70%, capacity factor = 50%, used factor = 60%, maximum demand = 20MW then annual energy production is 122.8 GWh

Description : In a synchronous generator delivering lagging power factor load  (1) the excitation emf leads terminal voltage by the power angle (2) the excitation emf lags terminal voltage by the power angle (3) ... by the power factor angle (4) excitation emf lags the terminal voltage by the power factor angle

Last Answer : In a synchronous generator delivering lagging power factor load the excitation emf leads terminal voltage by the power angle

Description : The sequence components of current of a single-phase load connected to a 3-phase system are (A) equal positive and negative sequence components (B) equal positive, negative and zero sequence components (C) vector sum of sequence currents is zero (D) algebraic sum of sequence currents is zero

Last Answer : The sequence components of current of a single-phase load connected to a 3-phase system are equal positive, negative and zero sequence components

Description : The power consumed by a balanced 3-ph load is measured by two-wattmeter method. The meter readings are 8 kW and 4 kW. The power factor of the load is (A) zero (B) 0.5 (C) between zero and 0.5 (D) between 0.5 and unity

Last Answer : The power consumed by a balanced 3-ph load is measured by two-wattmeter method. The meter readings are 8 kW and 4 kW. The power factor of the load is between 0.5 and unity

Description : The effect of increasing load on a synchronous motor running with normal excitation is (A) Increase both its Ia and power factor. (B) Decrease Ia, but increase power factor. (C) Increase Ia, but decrease power factor (D) Decrease both Ia and power factor.

Last Answer : The effect of increasing load on a synchronous motor running with normal excitation is Increase Ia, but decrease power factor

Description : Sparking occurs when a load is switched off because the circuit has high?

Last Answer : Sparking occurs when a load is switched off because the circuit has high inductance.

Description : In a lamp load when more than one lamp are switched on the total resistance of the load?

Last Answer : In a lamp load when more than one lamp are switched on the total resistance of the load decreases.

Last Answer : For given maximum axle load tractive efforts of AC. locomotive will be more than that of D.C. locomotive.

Last Answer : The power factor of a single phase load can be calculated if the instruments available are three ammeters or three voltmeters.

Last Answer : In a level compounded D.C. generator, full load terminal voltage is equal to no-load terminal voltage.

Last Answer : In over compounded generator, full load terminal voltage is more than no load terminal voltage.

Last Answer : If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens this will make armature to take heavy current, possibly burning it.

Last Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.