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

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

Voltage commutation results in best performance in thyristor D.C. chopper .

voltage commutation

## Related questions

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Description : A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would  (1) increase progressively  (2 ... 0.5 and then increase  (4) increase to a maximum value at α = 0.5 and then decrease

Last Answer : A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would increase to a maximum value at α = 0.5 and then decrease

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Last Answer : Yes, we can use triac in the multi-quadrant chopper.

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Description : Explain two-quadrant chopper.........

Last Answer : Two quadrant chopper:  There are two semiconductor controllable switches in the two-quadrant chopper. Two quadrant type A chopper: The figure shows the type A chopper. Both the switch never turn on at ... 2 are turned on then Vo=Vs. When chopper 1 and chopper 2 are off then Vo=-Vs.

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

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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.

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Last Answer : Thyristor commutation means turning off thyristor.

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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.

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Description : Draw circuit diagram of Class B commutation.

Last Answer : Class B: Resonant Pulse Commutation:

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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

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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.

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

Last 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 ... , the firing of auxiliary SCR commutates the main SCR, hence name is auxiliary commutation.

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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

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Description : An FET is a better chopper than a BJT because it has (A) lower offset voltage (B) higher series ON resistance (C) lower input current (D) higher input impedance

Last Answer : An FET is a better chopper than a BJT because it has lower offset voltage

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Description : Chopper controlled DC motor

Last Answer : Chopper controlled DC motor

180 views

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.

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Description : Draw a neat circuit diagram of class F commutation

Last Answer : class F commutation

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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

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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.

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Description : What are the different types of chopper with respect to commutation process?

Last Answer : a. Voltage commutated chopper. b. Current commutated chopper. c. Load commutated chopper.

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Description : Which of the following problem arises in D.C. motors which are fed from thyristor bridge circuits ? (a) Increased I R losses (b) Increased core losses (c) Poor commutation (d) Change in motor parameters (e) All of the above

Last Answer : (e) All of the above

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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

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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

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Description : The duty ratio of a step-up chopper with an output voltage of 200 V from a 80 V dc source, is (A) 0.4 (B) 0.5 (C ) 0.6 (D) 1.5

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Description : Is gate turn on mechanism of GTO is similar to conventional thyristor?

Last Answer : Yes gate turn on mechanism of GTO is similar to conventional thyristor.

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Description : A thyristor is triggered by a pulse train of 5 kHz. The duty ratio is 0.4. If the allowable average power is 100 W, the maximum allowable gate drive power will be

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Description : In a thyristor, the magnitude of anode current will:

Last Answer : In a thyristor, the magnitude of anode current will: Not change with any variation in gate current

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Description : A thyristor (SCR) turns off when the  A) Gate pulse is removed B) Gate pulse is applied C) Thyristor current is below holding value D) Anode voltage is made negative

Last Answer : A thyristor (SCR) turns off when the Thyristor current is below holding value

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Description : Turn-on of a thyristor (SCR) takes place when  A) Anode to cathode voltage is positive B) Anode to cathode voltage is negative C) Positive current is applied to gate D) Anode to cathode voltage is positive and positive current pulse is applied to gate

Last Answer : Turn-on of a thyristor (SCR) takes place when Anode to cathode voltage is positive and positive current pulse is applied to gate

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Description : The number of p-n junctions in a thyristor are  A)1 B) 2 C) 3 D) 4

Last Answer : The number of p-n junctions in a thyristor are  3

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Description : Anode current in an thyristor is made up of   (A) electrons only (B) electrons or holes (C) electrons and holes (D) holes only

Last Answer : Anode current in an thyristor is made up of electrons and holes

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Description : In a thyristor, holding current is   (a) More than latching current IL (b) Less than IL (c) Equal to IL (d) Very small

Last Answer : In a thyristor, holding current is Less than IL

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Description : Thyristor can be protected from over voltages by using

Last Answer : Thyristor can be protected from over voltages by using Voltage clamping device

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Description : Leakage current flows through the thyristor in

Last Answer : Leakage current flows through the thyristor in Forward blocking mode and Reverse blocking mode.

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Description : What is a phase control thyristor?

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Description : Why thyristor are not preferred for inverter?

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Description : What is thyristor family?

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Description : What is meant by firing angle of thyristor?

Last Answer : The point at which SCR is triggered is known as firings angle of thyristor.

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Description : What is the use of a thyristor in a circuit?

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Description : What is a reverse conducting thyristor?

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Description : What is the function of a thyristor?

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Description : Why SCR is called as thyristor?

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Description : Is a SCR a thyristor?

Last Answer : Yes, SCR is a thyristor. Thyristor is the family and SCR is the member of that family but SCR is universally known as thyristor.

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Description : How is a thyristor used to convert AC to DC?

Last Answer : thyristor

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Description : What is the application of thyristor?

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Last Answer : Yes ,it is one of the main advantage using thristors as a  switch in DC  circuit ,it has a high current gain

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Description : Explain thyristor gate drive circuit.

Last Answer : Thyristor Gate Drive Circuit: The thyristor can be turned on by pulse voltage signal at gate terminal and it does not require continuous drive signal like the transistor. The gate ... circuit provide required minimum gate voltage and gate current then the thyristor conducts properly.

302 views

Description : parallel operation of MOSFET can be done more easily as compared to thyristor. why?

Last Answer : Parallel operation of MOSFET can be done more easily as compared to thyristor because the resistance of MOSFET is increases with increase in temperature. MOSFET have the positive temperature coefficient. In ... the parallel operation of MOSFET can be done more easily as compared to the thyristor.

896 views

Description : what are the disadvantages of thyristor?

Last Answer : Disadvantages of thyristor The silicon controlled rectifier (SCR) is unidirectional devices, so it can control power only in DC power during positive half cycle of AC supply. Thus only DC power is ... cycle. It cannot be used at higher frequencies. The gate current cannot be negative

108 views

Description : write short notes on thyristor CSI .

Last Answer : Current-source inverter (CSI) is an inverter with a DC current input. Current source inverters are most commonly used in very high power AC motor drives.