Explain auxiliary commutation with a neat diagram. Also draw its waveform.

Explain auxiliary commutation with a neat diagram. Also draw its waveform.
by
retagged

1 Answer

Answer :

Auxiliary Commutation At start, the Ta is triggered and turned on to carry the load current. Due to the resonant circuit R-L-C, the current initially rises, attains peak and then falls to zero. This turns off the auxiliary SCR Ta. This current charges the capacitor C with upper plate positive. The capacitor thus forward biases the main SCR T. When main SCR T is triggered, it is turned on and charged capacitor C is placed across Ta so as to apply reverse bias across it. The load current now flows through T. The capacitor continues to discharge through T, L and D. Since this LC is resonant combination, the capacitor discharges completely first and then charges with opposite polarity till the current falls to zero. The capacitor current cannot reverse because of diode D. Now the oppositely charged capacitor forward biases the auxiliary SCR Ta. Thus when Ta is triggered, T is turned off and the same cycle is repeated. In this configuration, the firing of auxiliary SCR commutates the main SCR, hence name is auxiliary commutation.

image

by

Related questions

Draw circuit diagram of Class B commutation.

Description : Draw circuit diagram of Class B commutation.

Last Answer : Class B: Resonant Pulse Commutation:

Draw a neat circuit diagram of class F commutation

Description : Draw a neat circuit diagram of class F commutation

Last Answer : class F commutation

For a class D commutation, answer the following: i) Explain the operation with circuit diagram. ii) Interpret with waveforms.

Description : For a class D commutation, answer the following: i) Explain the operation with circuit diagram. ii) Interpret with waveforms.

Last Answer : Class D commutation: This is also called as auxiliary commutation because it uses an auxiliary SCR to switch the charged capacitor across conducting SCR to turn it off. In this scheme, the main ... make SCR1 forward biased and keep ready for next triggering. The above cyclic process is repeated.

Differentiate between Natural and Forced commutation

Description : Differentiate between Natural and Forced commutation

Last Answer : Natural commutation Forced commutation Source is AC Source is DC External commutating componants are not required  External commutating componants are required SCR turns off ... in controlled rectifiers, AC voltage controllers etc.  Used in choppers & inverters etc

Class D commutation

Description : Class D commutation

Last Answer : Class D commutation: This is also called as auxiliary commutation because it uses an auxiliary SCR to switch the charged capacitor across conducting SCR to turn it off. In this scheme, the main ... make SCR1 forward biased and keep ready for next triggering. The above cyclic process is repeated.

Define commutation. Give the types of commutation.

Description : Define commutation. Give the types of commutation.

Last Answer : Commutation: The process of turning-off a conducting thyristor is called commutation . Types of Commutation: i) Line commutation (Natural commutation) ii) Load commutation iii) Forced commutation iv) ... Auxiliary commutation v) Class E: External pulse commutation vi) Class F: AC line commutation

In a thyristor D.C. chopper, which type of commutation results in best performance ?

Description : In a thyristor D.C. chopper, which type of commutation results in best performance ?

Last Answer : voltage commutation

What is the purpose of auxiliary controller in substation?

Description : What is the purpose of auxiliary controller in substation?

Last Answer : The systems of substation auxiliaries ensure operation of substations providing internal consumers of substations with operating direct and alternating currents. Any breakdown (loss) of auxiliary systems ... whole substation, as well as serious problems during its subsequent putting into operation.

Centrifugal switch disconnects the auxiliary winding of the motor at about what percent of synchronous speed?

Last Answer : Centrifugal switch disconnects the auxiliary winding of the motor at about 70 to 80 percent of synchronous speed.

In split-phase motor auxiliary winding is of?

Last Answer : In split-phase motor auxiliary winding is of thin wire placed at the top of the slots.

In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to?

Last Answer : In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to improve power factor.

Class A Load Commutation

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. 

In a 3-phase converter circuit during commutation when one SCR in one phase is turned on to turn-off an SCR

Description : In a 3-phase converter circuit during commutation when one SCR in one phase is turned on to turn-off an SCR in another phase, results in (A) voltage notching (B) harmonic distortion (C) voltage sag (D) voltage swell

Last Answer : In a 3-phase converter circuit during commutation when one SCR in one phase is turned on to turn-off an SCR in another phase, results in voltage notching

Satisfactory commutation of D.C. machines requires?

Last Answer : Satisfactory commutation of D.C. machines requires brushes should be of proper grade and size, brushes should smoothly run in the holders, smooth, concentric commutator properly undercut.

What is mean by forced commutation of thyristor?

Last Answer : By using some circuit the forward DC current of thyristor is forced to zero is called forced commutation.

What is mean by natural commutation of thyristor?

Last Answer : Natural commutation is also called as line Communication. The turning off of thyristor due to AC supply is called natural commutation or line commutation. If the thyristor is connected to AC supply ... connected to positive and anode terminal get connected to negative, this turns off the thyristor.

what is thyristor commutation?

Last Answer : Thyristor commutation means turning off thyristor.

Give the operation of single phase full wave bridge controlled converter with RL load with a neat diagram. Also draw its waveform.

Description : Give the operation of single phase full wave bridge controlled converter with RL load with a neat diagram. Also draw its waveform.

Last Answer : Single phase fully control bridge converter with RL load: 1. During positive half cycle of input voltage, T1 and T2 are forward biased and during negative half cycle, T3 and T4 are forward biased. Therefore, T1-T2 ... cycle till the firing of next pair of SCRs as shown in the waveform.

Draw a neat diagram of 1Ф half wave controlled converter with RL load. Give its operation.

Description : Draw a neat diagram of 1Ф half wave controlled converter with RL load. Give its operation.

Last Answer : Single phase fully controlled half wave converter:  The circuit diagram of single-phase half-wave controlled rectifier with RL load and without freewheeling diode is shown in Fig. (a). The SCR T is ... , when again pulse is applied, the SCR is turned on & the above cycle is repeated. 

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

The introduction of interpoles in between the main pole improves the performance of d.c. machines, because (A) The interpole produces additional flux to augment the developed torque. (B) The flux waveform is improved with reduction in harmonics. (C) The inequality of air flux on the top and bottom halves of armature is removed. (D) A counter e.m.f. is induced in the coil undergoing commutation.

Description : The introduction of interpoles in between the main pole improves the performance of d.c. machines, because (A) The interpole produces additional flux to augment the developed torque. (B) The flux waveform is ... armature is removed. (D) A counter e.m.f. is induced in the coil undergoing commutation.

Last Answer : Ans: D Counter e.m.f is produced, it neutralizes the reactive emf.

Which of the following is also called as voltage commutation?

Description : Which of the following is also called as voltage commutation?   (a) CLASS A (b) CLASS B (c) CLASS C (d) CLASS D

Last Answer : Which of the following is also called as voltage commutation?   (a) CLASS A (b) CLASS B (c) CLASS C (d) CLASS D

Draw a neat sketch of earth fault protection of auxiliary circuit of electric loco. State the function of relay and isolating resistance.

Description : Draw a neat sketch of earth fault protection of auxiliary circuit of electric loco. State the function of relay and isolating resistance.

Last Answer : Ans: Earth fault protection for auxiliaries in Loco: Function of relay: The earth fault occurring anywhere in the auxiliary circuit gets monitored by the relay which acts to trip the main CB. Function of ... star point to earth through a high resistance so that the relay operation is avoided.

Describe working of negative clamper circuit with neat diagram and waveform.

Description : Describe working of negative clamper circuit with neat diagram and waveform.

Last Answer : Working: In the first positive half cycle the capacitor will charge through the forward biased diode to peak voltage Vm as shown in circuit. Charging takes place very quickly as the ... reverse biased and stop conducting. Negative clamper adds a negative DC shift as shown in waveform.

Draw the circuit diagram of bridge rectifier with π filter. Draw its input and output waveform.

Description : Draw the circuit diagram of bridge rectifier with π filter. Draw its input and output waveform. 

Last Answer : Circuit diagram of bridge rectifier with π filter : Input and output waveform:

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.

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 a symbol and neat labeling V-I characteristics of GTO and explain its operation.

Description : Draw a symbol and neat labeling V-I characteristics of GTO and explain its operation.

Last Answer : Ans: Symbol and V-I characteristics of GTO: Operation of GTO: i) As the applied anode to cathode voltage is increased above zero, very small current (leakage current) flows through the device. ... low voltage (VBRR). The reverse breakdown voltage is of the order of 20 to 30 volt only. 

Draw a neat labelling V-I characteristics of SCR and explain the region

Description : Draw a neat labelling V-I characteristics of SCR and explain the region

Last Answer : (i) Latching current: It is the minimum anode current required to maintain the SCR in the conduction state just after turn-on and the gate signal has been removed.  (ii) Holding current: It is the minimum anode current required to hold the conducting SCR in the ON state. 

With neat diagram explain synchronized UJT triggering circuit.

Description : With neat diagram explain synchronized UJT triggering circuit.

Last Answer : Line Synchronized UJT triggering circuit: The UJT is almost ideal as a firing device for SCRs. There are 2 main reasons for the compatibility between UJTs and SCRs. Firstly, the UJT produces a ... , the SCR is sure to have the right polarity between the anode and cathode for turning on.

With neat circuit diagram explain working of emergency light system.

Description : With neat circuit diagram explain working of emergency light system. 

Last Answer : Emergency lighting system:  In the residential, commercial and industrial areas, the illumination system work with available AC supply. In the event of AC supply failure, partial illumination can be ... glows. In rthis way, on failure of AC supply, light is obtained from DC supply.

Explain the operation of UPS with a neat block diagram.

Description : Explain the operation of UPS with a neat block diagram.

Last Answer : Uninterruptible-Power-Supplies (UPS): A block diagram of UPS system is shown in figure. It essentially consists of four major components: i)Rectifier (or battery charger) ii) ... . Due to fast action requirement, transfer switch can be implemented by fast acting semiconductor devices.

Explain the operation of RC triggering circuit with neat diagram.

Description : Explain the operation of RC triggering circuit with neat diagram.

Last Answer : RC triggering circuit: The RC half-wave triggering circuit is as shown in the figure. During negative halfcycle of supply voltage vs, the capacitor C charges through diode D2 and load, ... be triggered at 0° & 180° because the supply voltage is zero and less than finger voltage. 

Natural commutation means:

Description : Natural commutation means: A) reducing the thyristor current to zero B) reducing the thyristor current below “holding current” C) reducing the current to zero and allowing time to recover thyristor junctions D) none of (A), (B) and (C)

Last Answer : Natural commutation means: reducing the current to zero and allowing time to recover thyristor junctions 

Draw neat labeled diagram of AC track circuit. Also give two advantages of AC track circuit.

Description : Draw neat labeled diagram of AC track circuit. Also give two advantages of AC track circuit.

Last Answer : AC Track Circuit:  Advantages of AC Track Circuit: 1. Free from effects of stray currents. 2. Track circuit is up to a long length of track in one section length up to 3km to 5 km. 3. Cheaper in costs as compared to DC track circuit. 4. Easy to install than DC track circuit. 

working of SMPS with neat block diagram.

Description : working of SMPS with neat block diagram.

Last Answer : Diagram:  Working principle:-  Rectifier and filter:- It converts the ac supply voltage to a pulsating dc, which is then filtered out to reduce the amount of ripple content. ... PWM controller provides a duty-cycle that varies pulse by pulse to provide an accurate dc output voltage.

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.

A single-phase voltage source square -wave inverter feeds pure inductive load. The waveform of the load current will be

Description : A single-phase voltage source square -wave inverter feeds pure inductive load. The waveform of the load current will be

Last Answer : A single-phase voltage source square -wave inverter feeds pure inductive load. The waveform of the load current will be triangular

Draw a neat diagram of ‘Scotch Yoke Mechanism’. Explain its constructional features in brief.

Description : Draw a neat diagram of ‘Scotch Yoke Mechanism’. Explain its constructional features in brief.

Last Answer : Constructional Features of Scotch Yoke Mechanism: [1] In this mechanism, two sliding pairs and two turning pairs are used. So it is an inversion of Double Slider Crank Chain Mechanism. [2] It ... - Reciprocating Motion [3] The inversion is obtained by fixing either the Link 1 or Link 3. 

Draw circuit diagram of symmetrical configuration of bridge converter.

Description : Draw circuit diagram of symmetrical configuration of bridge converter.

Last Answer : circuit diagram of symmetrical configuration of bridge converter

Explain the operation of a full wave bridge rectifier with π filter using a neat diagram. Draw input and output waveforms.

Description : Explain the operation of a full wave bridge rectifier with π filter using a neat diagram. Draw input and output waveforms.

Last Answer : During positive half-cycle of input, the secondary voltage VAB is positive, so diodes D1 and D2 forward biased and D3 and D4 reverse biased. The load current flows from terminal A ... smooth DC voltage appears across the load. The input and output waveforms are shown in the figure.

Draw neat block diagram of FM receiver and explain function of each block

Description : Draw neat block diagram of FM receiver and explain function of each block

Last Answer : Explanation:-  RF amplifier: There are two important functions of RF amplifier: 1) To increase the strength of weak RF signal. 2) To reject image frequency signal. In FM ... FM broadcast, the maximum modulating frequency is 15 kHz. Hence the audio amplifier must have large bandwidth.

Draw a neat labelled diagram of PLC. Explain the function of each block.

Description : Draw a neat labelled diagram of PLC. Explain the function of each block.

Last Answer : Block Diagram of PLC:-  A simplified block diagram of a PLC shown in above Fig. It has three major units/sections.  I/O (Input/Output) Modules.  CPU (Central ... membrane keypad for program entry, and a display device (LED or LCD) for viewing program steps of functions. 

Explain with necessary diagram the earth fault protection of power and auxiliary circuit.

Description : Explain with necessary diagram the earth fault protection of power and auxiliary circuit.

Last Answer : i) Earth fault protection for power circuit in Loco: When any earth fault occurs in the traction power circuit the fault current flows through the relay coil as the battery negative is ... temporarily by isolating the relay which connects the star point to earth through a high resistance.

With help of circuit diagram and waveform, explain working of positive series clipper.

Description : With help of circuit diagram and waveform, explain working of positive series clipper.

Last Answer : Series Clipper (Positive):-   Working: For positive cycle the diode D is reverse biased. Hence there is no voltage across the load RL While for negative half wave, the diode D is forward biased. Hence ... positive cycle of the input voltage gets clipped off. Input & o/p wave form:-   

With help of circuit diagram and waveform, explain working of CLC or π- filter.

Description : With help of circuit diagram and waveform, explain working of CLC or π- filter.

Last Answer : Circuit diagram CLC or Π filter:   Working : It consist of a filter capacitor C1 connected across the rectifier o/p , a choke L is series and another filter capacitor C2 connected across the load. ... to block. Therefore, only d.c component appears across the load and that is what we desire.  

With help of circuit diagram and waveform, explain shunt capacitor filter.

Description : With help of circuit diagram and waveform, explain shunt capacitor filter.

Last Answer : Circuit diagram and Waveform: OR Explanation: A filter circuit is one which removes the ac component present in the rectified output and allows the dc component to reach the ... which allows ac components. The remaining dc components present in the signal are collected at the output. 

Explain working of envelope detector with suitable diagram and waveform.

Description : Explain working of envelope detector with suitable diagram and waveform.

Last Answer : Envelope Detector: An Envelope Detector is an electronic circuit that takes a high frequency signal as input and provides an output which is as envelopes of the original signal. The capacitor ... decreases the responsiveness thus, real-world designs must be optimized for the application.

Explain with circuit diagram and waveform the operation of class AB push pull power amplifier.

Description : Explain with circuit diagram and waveform the operation of class AB push pull power amplifier.

Last Answer : Class AB Push Pull Power Amplifier:  Circuit Diagram:  Circuit Decription: The circuit consists of two centre-tapped transformers T1 and T2, two identical transistors Q1 and Q2 , Resistor R and ... two halves & produces a full sine wave in the load resistor. Waveform :

Explain full wave bridged rectifier with the help of circuit diagram and input output waveform.

Description : Explain full wave bridged rectifier with the help of circuit diagram and input output waveform.

Last Answer : 1. In positive half cycle (0 to Π): The end A of the secondary winding becomes positive and end B negative. This makes diode D1 and D4 forward biased while diode D2 and D3 are reverse biased. These two diodes will ... D2 and D3 when it is conducting is as follows.  B - D2 - RL - D3 - A