What is meant by knee point voltage?

What is meant by knee point voltage?
by

1 Answer

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.
by

Related questions

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%. 

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

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

Last Answer : 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% = ... point. Above this they cannot detect the fault correctly. Measuring CT operate in the ankle region.   

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 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. 

What is meant by voltage surge?

Description : What is meant by voltage surge?

Last Answer : Voltage surge is sudden excessive rise in voltage that may be dangerous to the electrical equipment of an installation. Voltage surge cause damage to insulation of the system. Voltage surges are caused because of lightning, switching on and off the load at high voltages

What Is Meant By Reactance Voltage?

Description : What Is Meant By Reactance Voltage?

Last Answer : An armature coil has certain self inductance. When coil undergoes commutation, there is change in current (di) in that coil and the commutation takes certain time(dt). Thus there is self-induced emf ... by L(di/dt). This EMF induced in the coil undergoing commutation is called reactance voltage.

What Is Meant By Insulation Voltage In Cables? Explain It?

Description : What Is Meant By Insulation Voltage In Cables? Explain It?

Last Answer : It is the property of a cable by virtue of it can withstand the applied voltage without rupturing it is known as insulation level of the cable.

What is meant by sequence control of ac voltage regulators?

Description : What is meant by sequence control of ac voltage regulators?

Last Answer : It means that the stages of voltage controllers in parallel triggered in a proper sequence one after the other so as to obtain a variable output with low harmonic content.

What is meant by voltage commutation?

Description : What is meant by voltage commutation?

Last Answer : In this process, a charged capacitor momentarily reverse biases the conducting thyristor and turn it off.

What is meant by recovery voltage?

Description : What is meant by recovery voltage?

Last Answer : The power frequency rms voltage appearing across the breaker contacts after the arc is extinguished and transient oscillations die out is called recovery voltage.

What is meant by flat voltage start.

Description : What is meant by flat voltage start.

Last Answer : In iterative methods of load flow solution, the initial voltages of all buses exept slack bus are assumed as 1+j0 pu.This is reffered as flat voltage profile.

What is meant by restriking voltage?

Description : What is meant by restriking voltage? 

Last Answer : The high voltage that will appear across the contact just after the quenching of the arc is called restriking voltage. 

The knee voltage (cut in voltage) of Si diode is a. 0.2 V b. 0.7 V c. 0.8 V d. 1.0 V

Description : The knee voltage (cut in voltage) of Si diode is a. 0.2 V b. 0.7 V c. 0.8 V d. 1.0 V

Last Answer : b. 0.7 V

Define: i) Knee voltage ii) Reverse saturation current

Description : Define: i) Knee voltage ii) Reverse saturation current 

Last Answer : i) Knee voltage : The applied forward voltage, at which the PN junction starts conducting and current starts increasing exponentially is called knee voltage. It is 0.7V for Si and 0. ... semiconductor diode caused by diffusion of minority carriers from the neutral regions to the depletion region.

‘Germanium diode knee voltage is lower than silicon diode knee voltage.' Justify.

Description :  ‘Germanium diode knee voltage is lower than silicon diode knee voltage.' Justify.

Last Answer : Justification: The band gap between conduction and valence band for Germanium (0.66eV) is less as compared to Silicon (1.11eV).Hence less energy is required to start conduction in Germanium diode. 

The most inefficient method of voltage reduction from the stand point of power loss, is a/an _____________. A. capacitor in series with the load B. inductor in series with the load C. capacitor and inductor in series with the load D. resistor in series with the load

Description : The most inefficient method of voltage reduction from the stand point of power loss, is a/an _____________. A. capacitor in series with the load B. inductor in series with the load C. capacitor and inductor in series with the load D. resistor in series with the load

Last Answer : Answer: D

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

What is meant by voltage follower?

Description : What is meant by voltage follower?

Last Answer : If the output voltage of an op-amp follows the input i.e., if the output voltage is equal to the input voltage it is called as a voltage follower.

What is meant by extra high voltage transmission?

Description : What is meant by extra high voltage transmission?

Last Answer : HT & LT  two types transmission in industrial line 

What is meant by impulse ratio of any lightning arrester?

Description : What is meant by impulse ratio of any lightning arrester?

Last Answer : Impulse ratio of any lightning arrester is the ratio of breakdown voltage of the wave of special duration to breakdown voltage of a 50Hz wave

What is meant by Lightning arrester or surge diverter?

Description : What is meant by Lightning arrester or surge diverter?

Last Answer : A Surge Diverter is a device that is connected between line and earth, i.e, in parallel with the equipment under protection at the substation. It limits the duration and amplitude of the follow current

What is meant by protective angle? Give its value for reliable operation?

Description : What is meant by protective angle? Give its value for reliable operation?

Last Answer : Protective angle is the vertical angle through the ground wire axis and the line passing from the ground wire axis to the outermost phase conductor. Its value for reliable protection is taken equal to 20-30 degrees

What is meant by Current Chopping?

Description : What is meant by Current Chopping?

Last Answer : Current Chopping is a phenomenon of current interruption before the natural current zero is reached.

What is meant by armature reaction?

Description : What is meant by armature reaction?

Last Answer : Answer: The action of armature m.m.f. on the main m.m.f. is known as armature reaction.

What is Meant by "Impedance" in Transformers?

Description : What is Meant by "Impedance" in Transformers?

Last Answer : ANSWER: Impedance is the current limiting characteristic of a transformer and is expressed in percentage.

What is Meant by Insulation "Class"?

Description : What is Meant by Insulation "Class"?

Last Answer : ANSWER: Insulation class was a popular way of referencing insulating materials in their ability to sustain long life while operating at different temperatures. Since it Is difficult and at times confusing to describe ... E, B, F & H; it is better to describe insulation as "insulation systems".

What is Meant by Temperature Rise in a Transformer?

Description : What is Meant by Temperature Rise in a Transformer?

Last Answer : ANSWER: Temperature rise in a transformer is the temper¬ature of the windings and insulation above the existing ambi¬ent or surrounding temperature, and is determined by the insulation class used in the transformer coils.

What is Meant by Regulation in a Transformer?

Description : What is Meant by Regulation in a Transformer?

Last Answer : ANSWER: Voltage regulation in transformers is the difference between the no load voltage and the full load voltage. This is usually expressed in terms of percentage. For example: A transformer delivers 100 ... from 2% to 4%, depending on the size and the application for which they are used

What is meant by “impedance” in transformers? Why is it important?

Description : What is meant by “impedance” in transformers? Why is it important?

Last Answer : A. Impedance is the current limiting characteristic of a transformer and is expressed in percentage. It is used for determining the interrupting capacity of a circuit breaker or fuse employed to protect the primary of a transformer

What is meant by regulation in a transformer?

Description : What is meant by regulation in a transformer?

Last Answer : A. Voltage regulation in transformers is the difference between the no load voltage and the full load voltage. This is usually expressed in terms of percentage. Example: A Transformer delivers 100 ... The regulation capacity varies depending on the size and the application for which they are used.

What Is Meant By Stator? What Is Meant By Rotor?

Description : What Is Meant By Stator? What Is Meant By Rotor?

Last Answer : In any electrical machine ( AC/DC motor or generator) the stationary member is called as stator. Similarly in all machines the rotating member is known as rotor.

What Is Meant By Full Pitched Winding?

Description : What Is Meant By Full Pitched Winding?

Last Answer : If the coil span is equal to pole pitch, the winding is called as full pitched winding.

What Is Meant By Short Pitched Winding?

Description : What Is Meant By Short Pitched Winding?

Last Answer : If the coil span is less than the pole pitch, the winding is called as shot-pitched winding. It is also known as short-chorded winding.

What Is Meant By Turbo Alternators?

Description : What Is Meant By Turbo Alternators?

Last Answer : Turbo alternators are high speed alternators. Because of high speed of rotation, the rotor diameter is reduced and the axial length is increased. Two or four poles are generally used and steam turbines are used as prime movers.

What Is Meant By Regenerative Braking?

Description : What Is Meant By Regenerative Braking?

Last Answer : When the supply is cutt off for a running motor, it still continue running due to inertia. In order to stop it quickly we place a load(resitor) across the armature winding and the motor should ... and due to load the motor stops quickly.This type of breaking is called as Regenerative Breaking .

What Is Meant By Armature Reaction?

Description : What Is Meant By Armature Reaction?

Last Answer : What Is Meant By Armature Reaction? The effect of armature flu to main flux is called armature reaction. The armature flux may support main flux or opposes main flux.

What is meant by Sag?

Description : What is meant by Sag?

Last Answer : The difference in level between points of supports and the lowest point on the conductor is called sag.

What is meant by synchronous condenser?

Description : What is meant by synchronous condenser?

Last Answer : An over excited synchronous motor running on no load is known as synchronous condenser. It is used to improve the power factor of the system.

What is meant by negative converter group in a cycloconverter?

Description : What is meant by negative converter group in a cycloconverter?

Last Answer : The part of the cycloconverter circuit that permits the flow of current during negative half cycle of output current is called negative converter group.

What is meant by positive converter group in a cycloconverter?

Description : What is meant by positive converter group in a cycloconverter?

Last Answer : The part of the cycloconverter circuit that permits the flow of current during positive half cycle of output current is called positive converter group.

What is meant by step-down cyclo-converters?

Description : What is meant by step-down cyclo-converters?

Last Answer : In these converters, the output frequency is more than the supply frequency.

What is meant by step-up cyclo-converters?

Description : What is meant by step-up cyclo-converters?

Last Answer : In these converters, the output frequency is less than the supply frequency.

What is meant by cyclo-converter?

Description : What is meant by cyclo-converter?

Last Answer : It converts input power at one frequency to output power at another frequency with one-stage conversion. Cycloconverter is also known as frequency changer.

What is meant by high frequency carrier gating?

Description : What is meant by high frequency carrier gating?

Last Answer : Thyristor is turned on by using a train of pulses from αto π. This type of signal is called as high frequency carrier gating.

What is meant by PWM control?

Description : What is meant by PWM control?

Last Answer : In this method, a fixed dc input voltage is given to the inverter and a controlled ac output voltage is obtained by adjusting the on and off periods of the inverter components. This is the most popular method of controlling the output voltage and this method is termed as PWM control.

What is meant by McMurray inverter?

Description : What is meant by McMurray inverter?

Last Answer : It is an impulse commutated inverter which relies on LC circuit and an auxiliary thyristor for commutation in the load circuit.

What is meant a parallel inverter?

Description : What is meant a parallel inverter?

Last Answer : An inverter in which the commutating elements are connected in parallel with the load is called a parallel inverter.

What is meant a series inverter?

Description : What is meant a series inverter?

Last Answer : An inverter in which the commutating elements are connected in series with the load is called a series inverter.