An SCR starts conducting with appreciable current when

1 Answer

Answer :

An SCR starts conducting with appreciable current when anode and gate both are positive

Related questions

Description : Once SCR starts conducting a forward current, its gate losses control over (A) Anode circuit voltage only (B) Anode circuit current only (C) Anode circuit voltage and current (D) None of the above

Last Answer : Anode circuit voltage and current 

Description : After firing as SCR, the gating pulse is removed. The current in the SCR will  1. remain the same 2. immediately fall to zero 3. rise up 4. None 

Last Answer : After firing as SCR, the gating pulse is removed. The current in the SCR will remain the same

Description : Surge current rating of an SCR specifies the maximum  (a) Repetitive current with sine wave (b) Non-repetitive current with sine wave (c) Non-repetitive current with rectangular wave (d) Repetitive current with rectangular wave  

Last Answer : Surge current rating of an SCR specifies the maximum Non-repetitive current with sine wave

Last Answer : SCR turned off when the anode current falls below holding current.

Description : What is holding current and latching current in SCR? Draw the gate characteristics of an SCR and explain the characteristics. What are the different signals which can be used for turning on SCR by gate control? compare them.

Last Answer : (i) Holding Current: Holding current is defined as the minimum anode current required to maintain conducting SCR in the on-state.  (ii) Latching Current: Latching current is defined as the ... the on-state immediately after the SCR has been turned on and the gate signal has been removed.

Description : What is the only way to cause an SCR to stop conducting?

Last Answer : The forward bias must be reduced below the minimum conduction level.

Description :  To turn a conducting SCR to off state, it is necessary to make : -  a) anode current less than holding current b)gate current zero  c) anode voltage less than break over voltage  d) gate voltage zero

Last Answer :  To turn a conducting SCR to off state, it is necessary to make : - anode current less than holding current

Description : Explain triggering of SCR using opto-coupler. State its advantages. 

Last Answer : Triggering of SCR using opto-coupler:  A simple opto-coupler based triggering circuit for SCR is shown in the figure. An optocoupler or opto-isolator is a combination of light source ... is small size and light weight device. iii)Interfacing with logic circuits is easily possible.

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.

Description : Explain the thermal triggering method of SCR. Enlist different triggering methods of SCR.

Last Answer : Types of Triggering: 1) Forward voltage triggering 2) Thermal triggering (Temperature triggering) 3) Radiation triggering (Light triggering) 4) dv/dt triggering 5) Gate triggering ... generated leakage current increases. This current gets multiplied internally and thyristor is turned on. 

Description : Explain working of AC circuit breaker using SCR with circuit diagram.

Last Answer : AC Circuit Breaker:  The circuit configuration of static AC circuit breaker using SCR is shown in the figure. When switch S' is closed, the SCRs T1 and T2 are fired in positive ... to non-availability of gate current. Thus the maximum time delay for breaking the circuit is one half-cycle.

Description : Temperature controller using SCR

Last Answer : Temperature controller using SCR The temperature control circuit is used to regulate the temperature. Figure shows the temperature control circuit using thermostat as temperature detector and SCR as ... half-cycle and heater gets connected to source to produce heat and raise the temperature.

Description : Compare SCR and TRIAC

Last Answer : SCR TRIAC It is an unidirectional device. It is a bidirectional device. It is turned-on by only positive gate current. It can be turned-on by either ... applications including lamp dimmer, heating control, zero voltage switched AC relay, small AC motor control etc.

Description : Describe triggering of SCR using UJT relaxation oscillator. 

Last Answer : I need it's operation

Description : How GTO is advantages over SCR

Last Answer : i) It is turned-off by negative gate pulse. ii) No commutation circuit required, reducing the cost, size, weight and volume of the circuit. iii) As commutation choke is not used, the associated acoustic ... turn off time permits high switching frequency. v) It has higher di/dt rating at turn-off. 

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. 

Description : Draw construction of SCR using two transistor model. Explain its operation.

Last Answer : Two Transistor Model of SCR or Thyristor

Description : Turn on time of an SCR can be reduced by using a:

Last Answer : Turn on time of an SCR can be reduced by using a: Rectangular pulse of high amplitude and narrow width

Description : During forward blocking state, the SCR has:

Last Answer : During forward blocking state, the SCR has: low voltage, large current

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

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

Description : Circuit turn-off time of an SCR is defined as the time  (A) taken by the SCR turn to be off (B) required for the SCR current to become zero (C) for which the SCR is reverse biased by the commutation circuit (D) for which the SCR is reverse biased to reduce its current below the holding current

Last Answer : Circuit turn-off time of an SCR is defined as the time for which the SCR is reverse biased by the commutation circuit 

Description : An SCR can only be turned off via it's   (A) cathode (B) anode (C) gates (D) none

Last Answer : An SCR can only be turned off via it's anode 

Description : Turn-on time of an SCR in series with RL circuit can be reduced by   (a) Increasing circuit resistance R (b) Decreasing R (c) Increasing circuit inductance L (d) Decreasing L 

Last Answer : Turn-on time of an SCR in series with RL circuit can be reduced by Decreasing L 

Description : SCR is more utilized as compared to Triac because it is

Last Answer : SCR is more utilized as compared to Triac because it is available with higher ratings

Description : A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is (A) 4.5 V (B) 6.75 V (C) 9 V (D) 13.5 V

Last Answer : A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is 9 V

Description : In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is (A) sinusoidal current (B) constant dc current (C) continuous rectangular pulses (D) alternating rectangular pulses

Last Answer : In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is alternating rectangular pulses

Description : An SCR without any external connections is considered as (A) two diodes in series (B) three diodes in series (C) two n-p-n transistors in series (D) two p-n-p transistors in series

Last Answer : An SCR without any external connections is considered as three diodes in series

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.

Last Answer : Yes, SCR is a unidirectional switch.

Description : What is the use of SCR?

Last Answer : SCR are use in lamp dimming, power regulators, motor control, rectifications of high power AC, control of welding machines and also use as switch these are some uses of silicon controlled rectifier.

Description : In a single-phase full converter, the number of SCRs conducting during overlap is   (a) 1 (b) 2 (c) 3 (d) 4 

Last Answer : 4

Description : Conducting part starts with external nostrils and extended upto____

Last Answer : Conducting part starts with external nostrils and extended upto____

Description : Conducting part starts with external nostrils and extended upto____

Last Answer : Conducting part starts with external nostrils and extended upto____

Description : Do one person's finances have an appreciable effect on the national economy?

Last Answer : yes. George bush’s finances keep getting larger, mine keep getting smaller.

Description : Most animal tissues contain appreciable amounts of lipid, when in the form of depot fat it consists largely of (A) Cholesterol ester (B) Phosphatides (C) Chylomicrons (D) Triacylglycerol

Last Answer : Answer : D

Description : __________ treatment is done for appreciable improvement in viscosity index of lubricating oil. (A) Acid (B) Solvent extraction (C) Alkali (D) Clay

Last Answer : (B) Solvent extraction

Description : Pick out the wrong statement. (A) Bronze is an alloy of copper & tin (B) Brass is an alloy of copper & zinc (C) The alloy named 'German silver' does not contain any silver (D) The ability of a material to fracture without appreciable deformation is called its ductility

Last Answer : (D) The ability of a material to fracture without appreciable deformation is called its ductility

Description : In cold working of metal as compared to its hot working (A) Cracks and blow holes are eliminated (B) Ductility and impact strength improves (C) Appreciable strain hardening is produced (D) Yield stress, hardness and fatigue strength is not at all affected

Last Answer : (C) Appreciable strain hardening is produced

Description : When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids? (A) At high fluid velocity (B) At low velocity (C) When fluid flows past a smooth surface (D) None of these

Last Answer : (A) At high fluid velocity

Description : Which of the following plants does not emit appreciable amount of SO2 in atmosphere? (A) Thermal power plant (B) Petroleum refinery (C) Nitric acid plant (D) Sulphuric acid plant

Last Answer : (C) Nitric acid plant

Description : In multistage equilibrium conversion of SO2 to SO3 (2SO2 + O2 ⇌ 2SO3 ), the reverse reaction becomes appreciable at a temperature of 550° C. The percentage equilibrium conversion of SO2 to ... some quantity of SO3 during intermediate stage (D) Maintaining low temperature & pressure in the converter

Last Answer : (C) Removing some quantity of SO3 during intermediate stage

Description : An earth formation which, although porous and capable of absorbing water does not provide an  appreciable supply to wells, is known as  (A) Aquifer  (B) Aquiclude  (C) Aquifuge  (D) None of these 

Last Answer : (B) Aquiclude 

Description : The materials which fracture even at small strains are termed as brittle, while those materials which exhibit an appreciable deformation before failure are termed as (A) Rigid (B) Tough (C) Ductile (D) Plastic

Last Answer : Option C

Description : A silicon controlled rectifier (SCR) is a solid state device used to change ________________. A. DC to AC and control relatively low load current B. AC to DC and control relatively high load ... to AC and control relatively high load current D. AC to DC and control relatively low load current

Last Answer : Answer: B

Description : Since the characteristics of the device shown in figure 'A' of the illustration includes a stable voltage and low current while operating, it can be suitably used in _____________. EL-0065 A. oscillators ... . class A and B amplifiers C. generator rectifier and filtering supplies D. all of the above

Last Answer : Answer: A

Description : What is latching current in SCR?

Last Answer : It is the minimum current required to latch(turn on) the SCR from forward blocking state to forward conduction state.

Description : What is holding current in SCR?

Last Answer : When scr is conducting current in forward conduction state, scr will return to forward blocking state when the anode current or forward current falls below a low level called Holding current Note: ... the turn off process. In general holding current will be slightly lesser than the latching current.

Description : Holding current for an SCR is best described as:  (1) The minimum current required for turn-off (2) The current required before an SCR will turn on (3) The amount of current required to maintain conduction (4) The gate current required to maintain conduction

Last Answer : Holding current for an SCR is best described as: The amount of current required to maintain conduction.

Description : Two identical conducting wires `AOB and COD` are placed at right angles to each other. The wire `AOB` carries an electric current `I_(1) and COD` carr

Last Answer : Two identical conducting wires `AOB and COD` are placed at right angles to each other. The wire `AOB` carries an electric ... )^(2)+I_(2)^(2))^(1//2)`