The current zero interruption, in oil and air blast circuit breakers, is achieved by?
Last Answer : The current zero interruption, in oil and air blast circuit breakers, is achieved by lengthening of the gap, cooling and blast effect.
Show More
437 views
1 answer
asked
Mar 19, 2018
by
anonymous
Last Answer : Circuit breakers usually operate under transient state of short-circuit current.
Show More
104 views
1 answer
asked
Mar 19, 2018
by
anonymous
Last Answer : Air blast circuit breaker is used for repeated duty.
Show More
78 views
1 answer
asked
Mar 19, 2018
by
anonymous
Which of the following circuit breakers has high reliability & minimum maintenance? (A) Bulk oil type CB (B) Air blast CB (C) Vacuum CB (D) Sulphur hexafluoride CB
Last Answer : Which of the following circuit breakers has high reliability & minimum maintenance? (A) Bulk oil type CB (B) Air blast CB (C) Vacuum CB (D) Sulphur hexafluoride CB
Show More
298 views
1 answer
asked
May 8, 2018
by
anonymous
The following is/are the characteristics of SF6 circuit breakers: (A) It does not need an auxiliary breaking chamber (B) Short break time of 2 to 2.5 cycles (C) All of the above (D) None of the above
Last Answer : The following is/are the characteristics of SF6 circuit breakers: (A) It does not need an auxiliary breaking chamber (B) Short break time of 2 to 2.5 cycles (C) All of the above (D) None of the above
Show More
109 views
1 answer
asked
May 8, 2018
by
anonymous
Last Answer : The time of closing the cycle, in modern circuit breakers is 0.003 sec.
Show More
123 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : Circuit breakers are essentially current carrying contacts called electrodes.
Show More
327 views
1 answer
asked
Mar 19, 2018
by
anonymous
A circuit breaker is designed to protect an electrical circuit from damage caused by : (A) Over load (B) Short circuit (C) Over current (D) All of the above
Last Answer : A circuit breaker is designed to protect an electrical circuit from damage caused by : (A) Over load (B) Short circuit (C) Over current (D) All of the above
Show More
106 views
1 answer
asked
May 8, 2018
by
anonymous
Magnetic circuit breakers use _________ A) Permanent magnets B) Earth magnets C) Solenoid D) All the above
Last Answer : Magnetic circuit breakers use Solenoid
Show More
115 views
1 answer
asked
Apr 29, 2018
by
anonymous
What is the maximum number of circuit breakers in a panel?
Last Answer : It depends on that which type of panel is this.
Show More
111 views
1 answer
asked
Mar 10, 2018
by
anonymous
Explain fuel system and air intake system in diesel electric power plant.
Last Answer : Fuel system and air intake system in diesel electric power plant : Fuel system: It consists of storage tank, strainers, fuel transfer pump and all day fuel tank. The fuel oil is supplied ... Filters are provided to remove dust particles from air which may act as abrasive in the engine cylinder.
Show More
123 views
1 answer
asked
Sep 8, 2018
by
anonymous
.jpg)
Air blast circuit breakers for 400 kV power system are designed to operate in (a) 100 microsecond (b) 50 millisecond (c) 0.5 sec (d) 0.1 sec
Last Answer : (b) 50 millisecond
Show More
30 views
1 answer
Last Answer : For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.
Show More
110 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : Overhead system can be designed for operation up to 400 kV.
Show More
210 views
1 answer
asked
Mar 20, 2018
by
anonymous
What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage: (A) Eddy Current and Hysteresis losses will be ... Current will be too much high (C) Transformer may start to smoke and burn (D) No effect
Last Answer : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage: (A) Eddy Current and Hysteresis losses will be ... will be too much high (C) Transformer may start to smoke and burn (D) No effect
Show More
795 views
1 answer
asked
May 8, 2018
by
anonymous
Last Answer : The relay with inverse time characteristic will operate within 5 to 10 sec.
Show More
115 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : An efficient and a well designed protective relaying should have good selectivity and reliability, economy and simplicity, high speed and selectivity.
Show More
136 views
1 answer
asked
Mar 19, 2018
by
anonymous
.jpg)
Last Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.
Show More
145 views
1 answer
asked
Mar 19, 2018
by
anonymous
State the functions of following elements: i) Diesel engine system ii) Air intake system iii) Engine exhaust system iv) Engine starting system.
Last Answer : i) Diesel engine system:- Four strokes Two strokes ii) Air intake system:- Air intake system is provided to supply air to engine cylinder for fuel combustion. iii) Engine exhaust system ... provided to rotate the engine initially until the firing starts and engine run under its own power.
Show More
92 views
1 answer
asked
Sep 7, 2018
by
anonymous
A lightening arrester connected between the line and earth in a power system (1) protects the terminal equipment against travelling surges (2) protects the transmission line against direct ... suppresses high frequency oscillations in the line (4) reflects back the travelling wave approaching it
Last Answer : A lightening arrester connected between the line and earth in a power system protects the terminal equipment against travelling surges
Show More
365 views
1 answer
asked
Apr 29, 2018
by
anonymous
For a 15-bus power system with 3 voltage controlled buses, the size of Jacobian matrix is
Last Answer : For a 15-bus power system with 3 voltage controlled buses, the size of Jacobian matrix is 25 x 25
Show More
2.2k views
1 answer
asked
Apr 27, 2018
by
anonymous
With fault clearing time, the transient stability of a power system
Last Answer : With fault clearing time, the transient stability of a power system decreases
Show More
153 views
1 answer
asked
Apr 27, 2018
by
anonymous
Last Answer : The steady state stability of the power system can be increased by connecting lines in parallel.
Show More
118 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to extinguish the arc.
Show More
177 views
1 answer
asked
Mar 20, 2018
by
anonymous
.jpg)
Explain the lighting scheme to be designed for each of the following: i) Special ward in hospitals ii) Dentist’s Cabin
Last Answer : i) Special ward in hospital: For the patients in the wards, lighting should create a cozy and pleasant atmosphere. Lighting in the wards should be planned in such a way that it meets the specific ... we use such as cements and bonding agents that we use to restore your teeth back to health.
Show More
190 views
1 answer
asked
May 3, 2020
by
anonymous
Last Answer : D.C. generators are normally designed for maximum efficiency around full-load.
Show More
102 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.
Show More
73 views
1 answer
asked
Mar 20, 2018
by
anonymous
Last Answer : Generators for peak load plants are usually designed for maximum efficiency at 50 to 75 percent full load.
Show More
139 views
1 answer
asked
Mar 20, 2018
by
anonymous
Briefly explain how the power factor of an inductive circuit can be improved.
Last Answer : As we know that power factor should be corrected to ensure that the current supplied is cost friendly. Meaning the power factor should be around one but not greater than one(0.8-0.9) in a ... an inductive circuit due to the inductive reactance which oppose the change of current in the ac circuit.
Show More
182 views
1 answer
asked
May 17, 2020
by
anonymous
State maximum power transfer theorem for DC circuit.
Last Answer : Maximum power transfer theorem for DC circuit: The maximum power transfer theorem states that the source or a network transfers maximum power to load only when the load resistance is equal ... removed (disconnected) ii) All internal independent sources are replaced by their internal resistances.
Show More
110 views
1 answer
asked
Sep 6, 2018
by
anonymous
List any two methods of reactive power measurement in 3 phase circuit.
Last Answer : Methods of reactive power measurement in 3 phase circuit: (i) Two single phase wattmeter method (ii) One single phase wattmeter method
Show More
173 views
1 answer
asked
Sep 6, 2018
by
anonymous
In a pure resistive circuit, the average power Pavg is ______ the peak power Pmax. (1) Double (2) One-half of (3) One-fourth (4) Equal to
Last Answer : In a pure resistive circuit, the average power Pavg is One-half of the peak power Pmax.
Show More
1.0k views
1 answer
asked
May 1, 2018
by
anonymous
A snubber circuit is connected to the power semiconductor device to reduce the (A) turn-on time (B) turn-off time (C) electrical stresses (D) thermal resistance
Last Answer : A snubber circuit is connected to the power semiconductor device to reduce the electrical stresses
Show More
174 views
1 answer
asked
Apr 28, 2018
by
anonymous
The power factor of a D.C. circuit is always?
Last Answer : The power factor of a D.C. circuit is always unity.
Show More
219 views
1 answer
asked
Mar 25, 2018
by
anonymous
In an A.C. circuit power is dissipated in?
Last Answer : In an A.C. circuit power is dissipated in resistance only.
Show More
88 views
1 answer
asked
Mar 25, 2018
by
anonymous
The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is?
Last Answer : The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is 6 kVAR.
Show More
733 views
1 answer
asked
Mar 25, 2018
by
anonymous
The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is?
Last Answer : The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is 32 kW.
Show More
465 views
1 answer
asked
Mar 25, 2018
by
anonymous
Pure inductive circuit takes power from the A.C. line when?
Last Answer : It takes power when voltage decreases and current increases.
Show More
1.1k views
2 answers
asked
Mar 25, 2018
by
anonymous
.jpg)
The power factor at resonance in R-L- C parallel circuit is?
Last Answer : since a rlc circuit at resonance behaves like a pure resistive circuit, i.e there is no phase difference between current and voltage, hence the power factor is unity.
Show More
974 views
2 answers
asked
Mar 25, 2018
by
anonymous
Power factor of an inductive circuit is usually improved by connecting capacitor to it in?
Last Answer : Power factor of an inductive circuit is usually improved by connecting capacitor to it in parallel.
Show More
278 views
1 answer
asked
Mar 25, 2018
by
anonymous
Power factor of an electrical circuit is equal to?
Last Answer : Power factor of an electrical circuit is equal to R/Z, cosine of phase angle difference between current and voltage, kW/kVA.
Show More
516 views
1 answer
asked
Mar 24, 2018
by
anonymous
What is the power factor of purely resistive circuit.
Last Answer : Unity that is 1
Show More
391 views
2 answers
asked
Mar 16, 2018
by
anonymous
Explain power relations in three phase circuit.
Show More
88 views
0 answers
asked
Mar 11, 2018
by
anonymous
Explain power in single phase AC circuit.
Show More
82 views
0 answers
asked
Mar 11, 2018
by
anonymous
How do you find power in a circuit?
Last Answer : Power can be find in a circuit by the means of meters .if an individual want to check for a power in a circuit he/she Calabria the meters on a high voltage range and put the meters Lee in parallel with the circuit he /she will know the amount of power within that circuit .
Show More
135 views
1 answer
asked
Dec 16, 2017
by
anonymous
What is drive circuit in power electronics?
Last Answer : Driver is used for Motion Control through the use of power electronics.
Show More
133 views
2 answers
asked
Sep 20, 2017
by
anonymous
A single core cable is designed to work for a single phase system with a peak voltage of 220 kV. The maximum permissible stress in the dielectric is not to exceed 20 kV/mm. For economical size, the overall core diameter of the cable is (A) 28.2 mm (B) 26.4 mm (C) 24.4 mm (D) 22.0 mm
Last Answer : A single core cable is designed to work for a single phase system with a peak voltage of 220 kV. The maximum permissible stress in the dielectric is not to exceed 20 kV/mm. For economical size, the overall core diameter of the cable is 22.0 mm
Show More
756 views
1 answer
asked
Apr 28, 2018
by
anonymous
Summerise the role of power system engineer.
Last Answer : Role of power system engineer: i. On the planning side he or she has to make decisions on how much electricity to generate ii. For operation of the power system he has to plan for ... for energy conservation and load management. viii. For solving the power system problems he has to update with
Show More
67 views
1 answer
asked
May 6, 2020
by
anonymous
State the functions of fuel system and exhaust system of a diesel power station.
Last Answer : Fuel system: It supplies fuel to engine for combustion purpose. It consists of Fuel Pump: - It supplies fuel to engine for combustion purpose. Strainer: - Are provided to remove suspended impurities and ... most of the noise. Chimney:- To exhaust gases in the atmosphere as high as possible.
Show More
97 views
1 answer
asked
Sep 8, 2018
by
anonymous
Explain starting system in diesel electric power plant.
Last Answer : Starting system in Diesel Electric Power Plant: It includes Storage battery, compressed air tanks, self-starter etc. The purpose of engine starting system is to rotate the engine initially while ... as Ammeters, Voltmeters, Wattmeters, Thermometers, Pressure gauges, Visible and audible alarm etc.
Show More
125 views
1 answer
asked
Sep 8, 2018
by
anonymous
