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The primary reason for low power factor is supply system is due to installation of induction motors.

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Answer : For high value of diversity factor, a power station of given installed capacity will be in a position to supply more number of consumers.

Answer : In a low power factor wattmeter the pressure coil is connected to the load side of the current coil.

Description : At which time power factor of the induction motor is low?

Answer : The power factor of the inducction motor is low at the time of starting as compare to while the induction motor is running.

Answer : In a distribution system, in order to improve power factor, the synchronous capacitors are installed at the receiving end.

Answer : A low utilization factor for a plant indicates that plant is used for stand by purpose.

Description : The benefit of power factor correction in a power system is (A) lower power consumption (B) increased demand charge (C) reduced load carrying capabilities in existing lines (D) reduced voltage profile

Answer : The benefit of power factor correction in a power system is lower power consumption

Description : Power factor of the system is kept high?

Answer : Power factor of the system is kept high to reduce line losses, to maximise the utilization of the capacities of generators, lines and transformers, to reduce voltage regulation of the line.

Description : Define: primary and secondary distribution system 

Answer : i) Primary Distribution:  It is a 3-phase, 3-wire transmission line connected in between receiving substation to Distribution substation. OR It is link between receiving substation & ... substation to consumer line. OR It is link between distribution transformer substation & consumer. 

Answer : When a D.C. series motor is connected to A.C. supply, the power factor will be low because of high inductance of field and armature circuits.

Answer : In an interconnected system, the diversity factor of the whole system increases.

Description : Which of the following is the least expensive protection for over current in low voltage system?  (A) Rewireable fuse (B) Isolator (C) Oil Circuit breaker (D) Air break circuit breaker

Answer : Which of the following is the least expensive protection for over current in low voltage system?  (A) Rewireable fuse (B) Isolator (C) Oil Circuit breaker (D) Air break circuit breaker

Answer : For a consumer the most economical power factor is generally 0.95 lagging .

Description : What is the difference between a line voltage and low voltage control system?

Answer : An induction motor has relatively high power factor at near full load.

Answer : Power plant having maximum demand more than the installed rated capacity will have utilisation factor more than unity.

Answer : Load factor of a power station is generally less than unity.

Answer : Load factor of a power station is defined as average load/maximum demand.

Description : Can a synchronous condenser improve power factor?

Answer : Yes, synchronous condenser can improve power factor.

Description : What is the maximum value of power factor?

Answer : 1 is the maximum value of power factor.

Answer : MOSFET have high current losses due to High on state resistance. Hence MOSFET is used for low power applications.

Answer : To protect most of the electrical equipment handling low power, the types of relays used are thermocouple, electronic and bimetallic.

Description : State the effects of low power factor on efficiency and voltage regulation of short transmission lines. 

Answer : i) Effect of Low power factor on efficiency:- When power factor of load reduces current drawn by transmission line increases so copper losses in transmission line increases, hence transmission ... increases, so voltage drop in transmission line increases so regulation increases. (Become Poor) 

Answer : In a low power factor wattmeter the compensating coil is connected in series with pressure coil.

Answer : Overhead lines for power supply to tramcars are at a minimum height of 10 m.

Description : What is the Power Supply specification for 8085AH microprocessor? A) Single +5V supply with 10% voltage margins B) Dual +5V supply with 10% voltage margins C) Single +10V supply with 5% voltage margins D) Dual +5V supply with 5% voltage margins 

Answer : What is the Power Supply specification for 8085AH microprocessor? A) Single +5V supply with 10% voltage margins B) Dual +5V supply with 10% voltage margins C) Single +10V supply with 5% voltage margins D) Dual +5V supply with 5% voltage margins 

Description : Draw the block diagram of regulated power supply, explain function of each block and draw waveforms of each stage.

Answer : 1. A step down transformer 2. A rectifier 3. A filter 4. A regulator Operation of Regulated Power Supply:- Step Down Transformer:- A step down transformer will ... regulator. A regulator will maintain the output constant even when changes at the input or any other changes occur.

Description : What is need of regulated power supply?

Answer : A regulated power supply is used to ensure that the output remains constant even if the input changes. But sometimes main supply voltage, load, and surrounding temperature keep changing and altering the ... power supply is needed that will accept an AC input and give a constant DC output.

Description : Two 100W, 200V lamps are connected in series across a 200V supply. The total power consumed by each lamp will be in Watts

Answer : 4800

Description : The time period of third harmonic of power supply frequency, in milliseconds, is (A) 20 (B) 3.33 (C) 6.66 (D) 60

Answer : The time period of third harmonic of power supply frequency, in milliseconds, is 6.66 

Answer : Rectifier is use in power supply to convert Alternating current (AC) to Direct Current (DC) .

Description : A control system having unit damping factor will give  (1) Oscillatory response (2) Undamped response (3) Critically damped response (4) No response

Answer : 1

Description : The damping factor of a particular system is unity, the system response will be

Answer : The damping factor of a particular system is unity, the system response will be critically damped

Description : Draw and explain bulk correction method for power factor & control.

Answer : Bulk correction method for power factor & control: i) Here individual starter controls the capacitors located at distribution panel. ii) Centralized compensation is employed in large industrial plants where many ... capacitor units in steps to maintain P.F. more than preset limit (0.95). 

Description : What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these

Answer : What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these

Description : Capacitors for power factor correction are rated in?

Answer : Capacitors for power factor correction are rated in kVAR.

Answer : The standard full-load power factor ratings for synchronous motors are unity or 0.8 leading.

Answer : For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.

Answer : The power loss is an important factor for the design of transmission line.

Description : What is the value of capacitance required to improve power factor from 0.7 to 0.9. Given that: Real power = 50 W Vrms of the source = 120 Frequency = 50 Hz   #powerfactor

Description : Why capacitors are used to improve power factor?

Answer :  Capacitors generate reactive power instead of that drawn from source which is required by inductive loads.so it reduce the reactive current which is drawn from source to be drawn from capacitor.This control in Electric bills cost.

Description : The ratio of active power to apparent power is known as____ factor.

Answer : The ratio of active power to apparent power is known as power factor.

Description : Power factor of an inductive circuit is usually improved by connecting capacitor to it in?

Answer : Power factor of an inductive circuit is usually improved by connecting capacitor to it in parallel.

Description : Power factor of an electrical circuit is equal to?

Answer : Power factor of an electrical circuit is equal to R/Z, cosine of phase angle difference between current and voltage, kW/kVA.

Description : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?

Answer : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field.

Description : At which power factor alternator is said to be overexcited?

Answer : At leading power factor alternator is said to be overexcited.

Description : In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?

Answer : In an alternator, at lagging power factor the generated voltage per phase as compared to that at unity power factor must be more than terminal voltage.

Description : Why do we need to correct power factor?

Description : Explain energy conservation method in lighting system by using installation of separate transformer / servo stabilizer.

Answer : Energy conservation techniques by installation of separate transformer / servo stabilizer: The luminous efficiency of lamps depends upon the voltage applied across the terminals. It gives its best ... the voltage constant in that installation for giving best luminous efficiency of lamps.

Description : Briefly explain how the power factor of an inductive circuit can be improved.

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. 

Description : Discuss how power factor tariff results into energy conservation.

Answer : Power factor tariff results into energy conservation: i) Applying incentives and penalties according to power factor is an effective way, which enables consumer to improve power factor so that he can ... finally leads to reduction in the current drawn by the load and helps for energy conservation.

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