The typical ratio of latching current to holding current in a 20A thyristor is : (A) 5.0 (B) 2.0 (C) 1.0 (D) 0.5

1 Answer

Answer :

The typical ratio of latching current to holding current in a 20 A thyristor is  2.0

Related questions

Description : In a thyristor Latching current is ________ than Holding current a) Equal b) Less c) Greater d) None

Last Answer : Ans: Greater

Description : In a thyristor Latching current is than holding current: - a) equal b) less c) greater d) none of the above

Last Answer : In a thyristor Latching current is than holding current: - greater

Last Answer : Thyristor can be turn on by positive gate pulse and the current will continue to flow through the device even when the gate voltage is low hence thyristor is called latching device.

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 : In thyristor. holding current is (A) More than the latching current (B) Less than the latching current (C) Equal to latching current (D) None of the above

Last Answer : In thyristor. holding current is less than the latching current

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

Description : A 220 V dc machine has an armature resistance o f 1-ohm. If the full load current is 20A, the difference in the induced voltage when the machine is running as a motor, and as a generator is

Last Answer : A 220 V dc machine has an armature resistance o f 1-ohm. If the full load current is 20A, the difference in the induced voltage when the machine is running as a motor, and as a generator is 40 V.

Description : A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the terminal voltage of 220V. If the same machine is run as a motor it takes a line current of 20A from 220V supply. The speed of ... . (B) more than 800 rpm. (C) less than 800 rpm. (D) both higher or lower than 800 rpm.

Last Answer : (C) less than 800 rpm.

Description : Define latching current.

Last Answer : Gate signal is to be applied to the thyristor to trigger the thyristor ON in safe mode. When the thyristor starts conducting the forward current above the minimum value, called Latching current, the gate ... which is applied to trigger the device in no longer require to keep the scr in ON position.

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 the GCF of 8b to the 3rd power and 20a to the 2nd power?

Last Answer : The GCF is 4.

Description : The diameter of Z-DNA is: (a) 34 A (b) 20A (c) 18A (d) 45A

Last Answer : Ans. ((c))

Description : I. 20a^2 + 51a + 28 = 0 II. 15b^2 − 61b + 56 = 0 1 : if a > b 2 : if a < b 3 : if a ≥ b 4 : if a ≤ b 5 : if a = b or the relation between a and b cannot be established.

Last Answer : 2 : if a < b

Description : Component F in the illustrated device is for _________. EL-0033 A. short circut protection B. latching the trip unit closed after resetting the breaker C. overload protection D. providing a flexible connection between the input terminal G and the tripping unit E

Last Answer : Answer: C

Description : ____ is used latching, locking, triggering. A. Solenoid B. Relay C. Linear Actuator D. Servo motors

Last Answer : A. Solenoid 

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

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 

Description : Leakage current flows through the thyristor in

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

Description : What is the difference between SCR and thyristor?

Last Answer : SCR is a type of thyristor. Like GTO, IGCT, MCT, TRIAC, DIAC etc. are the types of thyristor.

Description : The turn-off time of a thyristor is 30 is at 50°C. What is its turn-off time at 100°C ?

Last Answer : The turn-off time of a thyristor is 30 is at 50°C. What is its turn-off time at 100°C ? 60 microsecond

Description : During forward blocking state, a thyristor is associated with . (A) Large current and low voltage (B) Low current and large voltage (C) Medium current and large voltage (D) None of the above

Last Answer : A

Last Answer : Thyristor have three terminals anode, cathode and Gate.

Description : thyristor can be turned off by?

Last Answer : Thyristor can be turned off by making anode potential equal to cathode potential or by making anode potential less than cathode potential.

Last Answer : Thyristor commutation means turning off thyristor.

Last Answer : Thyristor can only be turned on by small gate pulse but it cannot be turn off by using gate hence thyristor is called semi controlled device.

Description : What is Thyristor ?

Last Answer : : A thyristor is a solid state semiconductor device consisting of four layers of P and N-type components. This is especially true of a dual mode switch.

Description : Which of the devices listed is indicated by the electronic symbol lettered as 'A', shown in the illustration? EL-0016 A. Thyristor B. Diode C. Capacitor D. Transistor

Last Answer : Answer: B

Description : What does the arrangement at coordinates '62E' shown in the illustration represent? EL-0099 A. Position recording drum and stylus B. Temperature compensating thyristor C. Miniature bridge rectifier D. Twisted wire pair within a shield

Last Answer : Answer: D

Description : Figure 'B' shown in the illustration represents a/an ____________. EL-0067 A. silicon controlled rectifier B. junction field effect transistor C. diac thyristor D. IG MOS field effect transistor

Last Answer : Answer: A

Description : A triac thyristor functions as a control device and is basically ________________. A. two NPN transistors in parallel with a common base lead B. a diode in series with a temperature sensitive capacitor C. two ... -back SCR's with a common gate lead D. a triode tube with an extra heavy grid element

Last Answer : Answer: C

Description : Figure 'A' of the diagram shown in the illustration represents a/an ____________. EL-0078 A. silicon controlled rectifier B. IG or MOS field effect transistor C. triac thyristor D. junction field effect transistor

Last Answer : Answer: B

Description : Figure 'B' of the diagram shown in the illustration represents a/an ____________. EL-0065 A. silicon controlled rectifier B. junction field effect transistor C. diac thyristor D. IG or MOS field effect transistor

Last Answer : Answer: B

Description : What are the different losses that occur in thyristor while operating?

Last Answer : Different losses that occur are Forward conduction losses during conduction of the thyristor Loss due to leakage current during forward and reverse blocking. Power loss at gate or Gate triggering loss. Switching losses at turn-on and turn-off.

Description : Why thyristor is considered as Charge controlled device?

Last Answer : During the triggering process of the thyristor from forward blocking state to forward conduction state through the gate signal, by applying the gate signal (voltage between gate and cathode) increases the ... By controlling the amount of charge we can control the turning on time of the scr.

Description : Do you know the advantages of speed control using thyristor?

Last Answer : A: Advantages: 1. Fast Switching Characteristics than Mosfet, BJT, IGBT 2. Low cost 3. Higher Accurate.

Description : What Are The Advantages Of Speed Control Using Thyristor?

Last Answer : Advantages : Fast Switching Characterstics than Mosfet, BJT, IGBT. Low cost. Higher Accurate.

Description : How output frequency is varied in case of a thyristor?

Last Answer : The output frequency is varied by varying the turn off time of the thyristors in the inverter circuit, i.e. the delay angle of the thyristors is varied.

Description : Why circuit turn off time should be greater than the thyristor turn-off time?

Last Answer : Circuit turn off time should be greater than the thyristor turn-off time for reliable turn-off, otherwise the device may turn-on at an undesired instant, a process called commutation failure.

Description : What losses occur in a thyristor during working conditions?

Last Answer : a. Forward conduction losses b. Loss due to leakage current during forward and reverse blocking. c. Switching losses at turn-on and turn-off. d. Gate triggering loss.

Description : How can a thyristor turned off?

Last Answer : A thyristor can be turned off by making the current flowing through it to zero.

Description : What are the different methods to turn on the thyristor?

Last Answer : a. Forward voltage triggering b. Gate triggering c. dv/dt triggering d. Temperature triggering e. Light triggering

Description : What is Thyristor?

Last Answer : Thyristor is a four or more layer semiconductor device & having 3 or more junctions. It is also called Silicon Controlled Rectifiers (SCR). A healthy SCR must block in both the directions at least 1MQ resistance, a fused SCR will conducts in both directions. 

Description : What is purpose of connecting thyristor bridges in parallel?

Last Answer : Thyristor bridges are connected in parallel to improve current rating.  

Description : Why reactors are provided in Thyristor bridges? 

Last Answer : Reactors are provided to limit the rate of rise of current (di/dt) in the device, thereby avoiding possible damage to the device. They also effect a proper sharing of load among thyristor bridges when connected in parallel. 

Description : What is the purpose of RC network across thyristor?

Last Answer : RC network across each thyristor protects against Hole Storage Effect.  

Description : What is Thyristor?

Last Answer : Thyristor is a four or more layer semiconductor device & having 3 or more junctions. It is also called Silicon Controlled Rectifiers (SCR). A healthy SCR must block in both the directions at least 1MΩ resistance, a fused SCR will conducts in both directions. 

Description : What is a thyristor ? What are its uses ?

Last Answer : A thyristor is a special kind of semi conductor device that uses internal feedback to produce latching action. Use : Used for controlling large amounts of load power in motors, heaters, lighting systems etc ... the latches like a open switch. This latch will always stay in open or close position.  

Description : What is a thyristor? What is an SCR?

Last Answer : A thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bi stable switches, conducting when their gate receives a current trigger, and continue ... ) is a four-layer solid state device that controls current. It is a type of thyristor.

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

Description : Describe the working principle of Thyristor operated dimmer with the help of circuit diagram.

Last Answer : Thyristor operated dimmer: A popular thyristor operated dimmer circuit employ TRIAC-DIAC phase control for low AC power control. During each half-cycle, the capacitor charges through (R1+VR1). When the ... time constant {C (R1+VR1)}. Thus by reducing VR1 the lamp brightness can be increased.