Draw the circuit diagram for finding out the knee point voltage and explain the procedure.

Draw the circuit diagram for finding out the knee point voltage and explain the procedure.
by

1 Answer

Answer :

image

Connect the circuit as shown. O/P of variac should be zero. Increase it to 5 Volts and take down the value of current from the ammeter. Now increase the voltage by 10% (5 + 10% = 5.5 V) and take the current reading. Now increase the voltage by 10% (5.5 V +0.55 V =6.05 V) and note down the current. Now keep on increasing voltage by 10% and note down current reading. At some value there will be 50% increase in current for 10% increase in voltage.

Example 40 -> 0.2 A

 40.4 -> 0.3 A (0.2 + 50% = 0.3 A). 

That point is the knee point voltage of that particular CT. From this point onwards a little increase in voltage will lead to a large increase in current, because the core is saturated fully. When we plot all the values on a graph taking current as X-axis and voltage as Y-axis, we will get the above graph. Protective relays operate between ankle point and knee point. Above this they cannot detect the fault correctly. Measuring CT operate in the ankle region. 

 

by

Related questions

Explain the procedure for finding out the polarity and ratio test in a CT with circuit diagram.

Description : Explain the procedure for finding out the polarity and ratio test in a CT with circuit diagram. 

Last Answer : Polarity test: Connect the circuit as shown in figure with a battery, switch and AVOmeter. Now momentarily close the switch S and see the deflection in the AVOmeter. If it is in the direction as shown in the ... A2. Then see whether it confirms to reading of nameplate. Ratio = A1/A2. 

Explain the procedure of finding area of irregular figure by polar planimeter. Also draw sketch of polar planimeter.

Description : Explain the procedure of finding area of irregular figure by polar planimeter. Also draw sketch of polar planimeter.

Last Answer : Procedure: 1. Set the scale on the tracing arm as per manufacturer's instruction. 2. Select the position of anchor point inside or outside the figure such that tracing point reaches all positions of ...  Use + sign for clockwise and - sign for anticlockwise crossing of zero of dial. 

What is meant by knee point voltage?

Description : What is meant by knee point voltage?

Last Answer : Knee point voltage is the voltage at which a CT gets saturated. It is one of the important factors taken into consideration for selecting a current transformer.

Define knee point voltage.

Description : Define knee point voltage.

Last Answer : The voltage applied to secondary of CT keeping the primary open at which 10% increase in voltage causes 50% increase in excitation current. 

What is Knee point voltage?

Description : What is Knee point voltage? 

Last Answer : EMF applied to secondary of current transformer (CT) which, when increased by 10% voltage causes the excitation current to increase by 50%. 

Define knee point voltage of a CT.

Description : Define knee point voltage of a CT.

Last Answer : When the primary of a CT is open circuited and supply (variable) of system frequency is given to secondary, then a 10% increase in voltage constitutes 50% increase in current. That voltage is the knee point ... Above kpv the ratio of transformer will not be applicable. kpv = RCT + RLEADS + RRELAY  

What is meant by knee point voltage?

Description : What is meant by knee point voltage?

Last Answer : Knee point voltage is calculated for electrical Current transformers and is very important factor to choose a CT. It is the voltage at which a CT gets saturated.

As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to _____________. A. draw a one line diagram of the circuitry B. test all fuses and measure the line voltage C. take megger readings D. insulate the apparatus from ground

Description : As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to _____________. A. draw a one line diagram of the circuitry B. test all fuses and measure the line voltage C. take megger readings D. insulate the apparatus from ground

Last Answer : Answer: B

Two unpedauces given by Z1 = 10 + j5 and Z2 = 8 + j9 are joined in parallel and connected across a voltage of V = 200 + j0. Calculate the circuit current and branch currents. Draw the vector diagram.

Description : Two unpedauces given by Z1 = 10 + j5 and Z2 = 8 + j9 are joined in parallel and connected across a voltage of V = 200 + j0. Calculate the circuit current and branch currents. Draw the vector diagram.

Last Answer : Solution: Given, Z1=10+j5, Z2=8+j9, V=200+j0

For R-C series circuit draw (i) Circuit diagram (ii) Vector diagram (iii) Waveform of voltage and current

Description : For R-C series circuit draw (i) Circuit diagram (ii) Vector diagram (iii) Waveform of voltage and current

Last Answer : i) Circuit diagram ii)Vector diagram iii)Waveform of voltage and current

Draw circuit diagram of voltage divider biasing list two advantages of voltage divider biasing of BJT.

Description : Draw circuit diagram of voltage divider biasing list two advantages of voltage divider biasing of BJT.

Last Answer : Two advantages of voltage divider biasing of BJT. 1. It is very simple method of transistor biasing. 2. The biasing conditions can be very easily set. 3. there is no loading of ... 5. The resistor RE introduces a negative feedback. So all the advantages of negative feedback are obtained. 

The wiring diagram for the motor starting circuit shown in the illustration indicates ______________. EL-0007 A. resistance starting B. reduced voltage starting C. low voltage protection D. low voltage release

Description : The wiring diagram for the motor starting circuit shown in the illustration indicates ______________. EL-0007 A. resistance starting B. reduced voltage starting C. low voltage protection D. low voltage release

Last Answer : Answer: C

Draw the basic block diagram of digital meter and explain the function of each block.

Description : Draw the basic block diagram of digital meter and explain the function of each block. 

Last Answer : Alternator: It reduces the unknown voltage to a small value. Because the reference voltage is very less and the unknown voltage is maximum. A/D converter: It converts the analog signal from ... and display: It decodes the binary code to decimal form and gives a visual display of it. 

Describe with neat circuit diagram the measurement procedure of earth resistance for an installation.

Description : Describe with neat circuit diagram the measurement procedure of earth resistance for an installation. 

Last Answer : Following procedure (Method) for testing of earth pit resistance with necessary diagrams. 1) Earth Tester : i) Three point method ii) Four point method 2) By Potential drop method 3) Water ... of that earthing pit. In this test the accuracy is less but electrical rods are not required.  

Draw the circuit diagram of glow plug and explain its operation.

Description : Draw the circuit diagram of glow plug and explain its operation.

Last Answer : Answer: Operation of glow plug: Glow plug is an aid for cold starting of a C.I. engine. The selfignition temperature of diesel is 250°C. For compression ignition, the charge (air + diesel) ... is automatically interrupted. But starting may be attempted again as soon as the driver wishes. 

Draw circuit diagram of transistor reactance modulator. Explain its working.

Description : Draw circuit diagram of transistor reactance modulator. Explain its working.

Last Answer : Explanation- A reactance modulator is illustrated in figure. It is basically a standard commonemitter class A amplifier. Resistors R1 and R2 from a voltage divider to bias ... frequency, whereas a lower capacitance increases the frequency. The circuit produces direct frequency modulations.

Draw block diagram of FM receiver and explain the use of limiter circuit.

Description : Draw block diagram of FM receiver and explain the use of limiter circuit.

Last Answer : Diagram Explanation Amplitude limiter: The function of amplitude limiter is to remove all amplitude variation of FM carrier voltage that may occur due to atmospheric disturbances. Use of amplitude limiter makes the system less noisy.

Draw the circuit diagram of practical diode detector and explain its working.

Description : Draw the circuit diagram of practical diode detector and explain its working. 

Last Answer : Circuit diagram of practical diode detector:  Explanation- The circuit operates in the following manner- The diode has been reversed so that now the negative envelope is demodulated. Due to this ... to produce AGC voltage. The DC AGC voltage is proportional to the amplitude of AM signal. 

Draw the circuit diagram of limiter and explain its working.

Description : Draw the circuit diagram of limiter and explain its working.

Last Answer : Circuit diagram of amplitude limiter:- Explanation:- 1. In frequency modulation, the signal amplitude is held constant while the carrier frequency is varied. 2. Any noise that contaminates ... V p-p instead of the alternately driven into saturation and cutoff, it limits the signal amplitude

Draw the circuit diagram of varactor diode FM modulator and explain its working.

Description : Draw the circuit diagram of varactor diode FM modulator and explain its working.

Last Answer : Varactor diode modulator is the direct method of FM generation wherein the carrier frequency is directly varied by the modulating signal. A varactor diode is a semiconductor diode whose ... the magnitude of frequency change is proportional to the amplitude of the modulating signal voltage.

Explain flat top sampling with circuit diagram.Draw flat top sampled signal.

Description : Explain flat top sampling with circuit diagram.Draw flat top sampled signal.

Last Answer : Flat top sampling: In flat top sampling, the top of the samples remains constant and equal to the instantaneous value of the modulating signal at the start of the sampling. Thus the ... the sampled signal and the pulse signal. Flat top sampling is mostly used in digital transmission

Draw the circuit diagram of Bootstrap’s time base generator and explain its working.

Description : Draw the circuit diagram of Bootstrap’s time base generator and explain its working.

Last Answer : Circuit Diagram Waveform: Here transistor Q1 acts as a switch and transistor Q2 acts as an emitter follower (i.e. a unit gain amplifier).  Circuit Operation: Initially transistor ... The circuit pulls itself up by its own bootstrap and hence it is known as bootstrap sweep circuit. 

Draw circuit diagram for π filter and explain its working with waveforms.

Description : Draw circuit diagram for π filter and explain its working with waveforms.

Last Answer : Working of a Pi filter: In this circuit, we have a capacitor in parallel, then an inductor in series, followed by another capacitor in parallel. Capacitor C1 − This filter capacitor ... any ac component present in the signal to pass through it, which the inductor has failed to block.

Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter.

Description : Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter. 

Last Answer : Circuit diagram for measurement of single phase power using dynamometer type wattmeter: Explanation: It consists of two stationary coils, called current coils and one moving coil, called voltage or ... i.e. power. The meter can be calibrated directly to indicate the power in watts. 

Draw the circuit diagram of battery charger using SCR and explain it’s working.

Description : Draw the circuit diagram of battery charger using SCR and explain it’s working.

Last Answer : Battery charger circuit using SCR: The figure shows the battery charger circuit using SCR. A 12V discharged battery is connected in the circuit and switch SW is closed. The singlephase 230V ... not fired. In this way, after full charging, further charging is automatically stopped.

Draw circuit diagram of Bistable multivibrator using IC-555 and explain its working.

Description : Draw circuit diagram of Bistable multivibrator using IC-555 and explain its working.

Last Answer : Definition – A multivibrator which has two stable states, one can be change to other when trigger pulse is applied, known as bistable multivibrator. Circuit diagram of Bistable multivibrator using IC555

Explain Center-tapped full wave rectifier with the help of circuit diagram and draw input output waveforms.

Description : Explain Center-tapped full wave rectifier with the help of circuit diagram and draw input output waveforms. 

Last Answer : Operation : During positive half cycle of an AC supply, D1 will forward biased and current starts flowing through load. The output voltage is equal to +Vs. During negative half cycle of an AC ... output voltage is equal to +Vs. In this pulsating DC waveform will be obtained at the load. 

Draw the circuit diagram of crystal oscillator and explain its working.

Description : Draw the circuit diagram of crystal oscillator and explain its working.

Last Answer : To excite a crystal for operation in the series-resonant mode it may be connected as a series element in a feedback path, the crystal impedance is the smallest and the amount of positive feedback is the largest. ... which is good.  The resonant frequency is given as  Fo = 1/( 2 π √LC ) 

Draw and explain Hartley Oscillator circuit diagram.

Description : Draw and explain Hartley Oscillator circuit diagram.

Last Answer : Function of each component: 1. An NPN transistor connected in a common emitter configuration works as the active device in amplifier stage and CE configuration provides 180°phase shift. 2. R1 and R2 ... circuit to the base-emitter circuit.  The frequency of oscillation is given as-  

What is knee point?

Description : What is knee point?

Last Answer : Knee point is the region, where 10% increase in flux causes 50% increase in exciting ampere-turns. 

Draw block diagram of Dual slope integrating voltmeter and also draw waveform for voltage V/s time.

Description : Draw block diagram of Dual slope integrating voltmeter and also draw waveform for voltage V/s time. 

Last Answer : Block diagram

Explain with circuit diagram, voltage divider biasing method and state its two advantages.

Description : Explain with circuit diagram, voltage divider biasing method and state its two advantages.

Last Answer : a)Here R1 and R2 forms voltage divider biasing arrangement. b)voltage drop across R2 ,forward biases the base emitter junction. c)so base current flows and hence collector ... Operating point stabilized against shift in temperature. · Operating point is almost independent of β variation

Sketch circuit diagram of transistorized series voltage regulator and explain its working.

Description : Sketch circuit diagram of transistorized series voltage regulator and explain its working.

Last Answer : * This regulator has a transistor in series to the Zener regulator and both in parallel to the load. The transistor works as a variable resistor, regulating its collector emitter voltage in ... of output voltage compensates the initial increase in output voltage. Thus it acts as a regulator. 

With the help of neat circuit diagram, explain the operation of voltage shunt type feedback amplifier.

Description : With the help of neat circuit diagram, explain the operation of voltage shunt type feedback amplifier.

Last Answer : Diagram:  Fig. shows common emitter transistor amplifier with a feedback resistor RF connected between its output and input terminals. This is collector to base biasing when the input signal is ... As IS = If + Ii it is shunt type therefore it voltage shunt negative feedback amplifier.

Explain with circuit diagram operation of zener diode as a voltage regulator.

Description : Explain with circuit diagram operation of zener diode as a voltage regulator.

Last Answer : The function of a regulator is to provide a constant output voltage to a load connected in parallel with it in spite of the ripples in the supply voltage or the variation in the load ... V0 = VZ is obtained across RL, whenever the input voltage remains within a minimum and maximum voltage.

Draw a neat sketch and explain the use of CT and PT for measurement of power in a single-phase circuit?

Description : Draw a neat sketch and explain the use of CT and PT for measurement of power in a single-phase circuit?

Last Answer : If wattmeter of proper range is not available or if voltage and current ranges are high we can usr CT and PT of suitable ratio. Connect the CT and PT as shown in figure. The reading of wattmeter can be multiplied by the ratio to get the actual power.   

What is the polarity of voltage at point 'Z' in the circuit shown in the illustration? EL-0085 A. It will always be positive. B. It will always be negative. C. It depends on the instantaneous polarity at point 'W'. D. It cannot be determined without a voltmeter.

Description : What is the polarity of voltage at point 'Z' in the circuit shown in the illustration? EL-0085 A. It will always be positive. B. It will always be negative. C. It depends on the instantaneous polarity at point 'W'. D. It cannot be determined without a voltmeter.

Last Answer : Answer: A

Draw the circuit diagram and describe the working principle of full wave bridge rectifier. Draw its waveforms.

Description : Draw the circuit diagram and describe the working principle of full wave bridge rectifier. Draw its waveforms. 

Last Answer : During the first half cycle : During the first half cycle of the input voltage, the upper end of the transformer secondary winding is positive with respect to the lower end. Thus during the first ... , terminal D, diode D4, and terminal A back to transformer and output will positive half cycle.

Draw the circuit diagram of multi range AC voltmeter and describe its working

Description : Draw the circuit diagram of multi range AC voltmeter and describe its working

Last Answer : The above circuit looks like a multi range AC voltmeter. We know that, we will get AC voltmeter just by placing rectifier in series (cascade) with DC voltmeter. The above circuit was created ... any two points of an electric circuit, by connecting the switch, S to the desired voltage range.

Draw the circuit diagram of bridge rectifier and label it.

Description : Draw the circuit diagram of bridge rectifier and label it. 

Last Answer : Circuit Diagram Bridge rectifier

Draw the circuit diagram of shunt capacitor filter along with full wave rectifier. Draw the waveform of full wave rectifier output and shunt capacitor filter output.

Description : Draw the circuit diagram of shunt capacitor filter along with full wave rectifier. Draw the waveform of full wave rectifier output and shunt capacitor filter output.

Last Answer : Fig: Shunt capacitor filter along with full wave rectifier Fig: Waveform of full wave rectifier output and shunt capacitor filter output.

Draw circuit diagram and waveforms for centre-tap full wave rectifier.

Description : Draw circuit diagram and waveforms for centre-tap full wave rectifier.

Last Answer : Circuit Diagram:    

Draw and describe circuit diagram of centre tapped rectifier with LC filter along with its input and output waveforms.

Description : Draw and describe circuit diagram of centre tapped rectifier with LC filter along with its input and output waveforms.

Last Answer : Explanation: A centre- tap full wave rectifier drive produces the rectified voltage and it drives the LC filter. We know that the series inductor filter is preferred for low values of load resistance ( ... load RL. The output voltage waveforms are similar to that as shown in figure above.  

Draw and label the circuit diagram of ratio detector

Description : Draw and label the circuit diagram of ratio detector 

Last Answer : Draw and label the circuit diagram of ratio detector  

Draw the circuit diagram of PWM using IC555. State its operation.

Description : Draw the circuit diagram of PWM using IC555. State its operation.

Last Answer : Operation: i. The timer IC555 is operated in monostable mode. ii. The negative going carrier pulses are to the differentiator formed by R1 & C1. The differentiator produces sharp negative ... . Thus PWM signal is generated at the output pin (3) of IC555 as monostablemultivibrator. 

Draw the circuit diagram of DC signal conditioning circuit.

Description : Draw the circuit diagram of DC signal conditioning circuit.

Last Answer : Circuit

Use Voltmeter, ammeter, wattmeter to determine active, reactive and apparent power consumed in given R—C series circuit, draw phasor diagram.

Description : Use Voltmeter, ammeter, wattmeter to determine active, reactive and apparent power consumed in given R—C series circuit, draw phasor diagram.

Last Answer : Use Voltmeter, ammeter, wattmeter to determine active, reactive and apparent power consumed in given R-C series circuit, draw phasor diagram. Practical Significance In the industry environment ... autotransformer position to zero and switch OFF the supply. 8. Draw the phasor diagram.

Use Voltmeter, ammeter, wattmeter to determine active, reactive and apparent power consumed in given R-L series circuit, draw phasor diagram.

Description : Use Voltmeter, ammeter, wattmeter to determine active, reactive and apparent power consumed in given R-L series circuit, draw phasor diagram.

Last Answer : Practical Significance In the industry environment Electrical Engineering diploma graduate are expected to measure basic parameters like voltage, frequency, time period etc. for R-L series circuits. Therefore ... /varying L. 7. Draw the phasor diagram for each of reading for verification.

Draw the circuit diagram for:- i) Measurement of active power in 3-phase load circuit using two wattmeter. ii) Measurement of reactive power in 3-phase load circuit using one wattmeter.

Description : Draw the circuit diagram for:- i) Measurement of active power in 3-phase load circuit using two wattmeter. ii) Measurement of reactive power in 3-phase load circuit using one wattmeter.

Last Answer : (i) Measurement of active power in 3- phase load circuit using two- wattmeter: (ii) Measurement of reactive power in 3- phase load circuit using one wattmeter